Lunch Colloquium
Dr. Andrei Lobanov	ORATED

MPIfR

Weakly interacting sub-eV particles (WISP) are steadily gaining more prominence as likely candidates for explaining the dark matter. The particular focus of attention is on the QCD axions, axion-like particles (ALP), and hidden photons with masses between 0.1 micro-eV and 10 meV (corresponding to the 24 MHz -- 2.4 THz frequency range). A number of WISP detection experiments have been performed and planned that cover parts of this frequency range. Searching for potential WISP dark matter signal in this entire frequency range requires making efficient, broadband measurements performed at a power sensitivity of better than 10^-23 W and a fractional spectral resolution of about 10^-6. This brings an excellent potential for synergies with recent developments in radioastronomy and in VLBI and millimeter and sub-millimeter areas in particular. One specific example of such synergies is the WISPDMX experiment operated in collaboration between the University of Hamburg, the MPIfR, and DESY. A short review of recent and planned WISP dark matter searches will be presented here, with a specific focus on the WISPDMX measurements providing the best exclusion limits on hidden photons in the 0.8-2.0 micro-eV energy range and on the plans to expand this effort to performing definitive Broadband Radiometric Axion Searches (BRASS) in the 0.01-5 meV (24-1000 GHz) energy range, which covers the most favorable theoretical "sweet spots" for the axion mass, hence bearing excellent prospects for discovering this elusive particle.

	Promotionskolloquium
Pablo Torne	ORATED

MPIfR

Pulsars are rapidly-rotating, highly-magnetised neutron stars that provide unique laboratories for a wide variety of physical experiments. During my thesis, I have investigated the application of new receiver technologies and observing techniques to the search for and study of radio pulsars. In particular, I have used one of the largest supercomputers in Europe, the MPCDF’s Hydra cluster, to analyse the data from a long-term survey of the Galactic Centre carried out with the 100-m Effelsberg radio telescope. Furthermore, I have used experimental, fast-sampling, broadband continuum receivers on Pico Veleta and APEX to perform the highest-radio-frequency pulsar observations to date, observing a sample of six pulsars and one magnetar. At lower frequency I have carried out commissioning work with the next generation of radio receivers for Effelsberg: the Ultra-Broad-Band receiver and the Phased Array Feed. In this colloquium, I will present the main results from these investigations, which include the analysis of the challenges of conducting pulsar surveys around the Galactic Centre and, for the first time, the detection and study of pulsar emission up to ~300 GHz. The latter provides invaluable experimental results needed for the development of more precise models of pulsar radio emission. I will conclude by discussing the big challenges, and their possible solutions, that the next generation of low-frequency receivers for Effelsberg must face, in particular in dealing with radio frequency interference.[Referees: Prof. Dr. Michael Kramer (Max-Planck-Institut für Radioastronomie); Prof. Dr. Frank Bertoldi (Argelander-Institut für Astronomie); Prof. Dr. Norbert Wermes (Physikalisches Institut, Universität Bonn); Prof. Dr. Albert Haas (Institut für Zellbiologie, Universität Bonn)]

	Master Colloquium
Felix Pötzl	ORATED

MPIfR

Star formation is a crucial component in the evolution of galaxies. Stars form mainly in the cold and dense molecular gas phase. Galaxies exhibit certain relations between their star formation rate (SFR) surface density and gas surface density, the Kennicutt-Schmidt law. Different modes of star formation have been postulated for starbursts and disk galaxies, but the determination of SFRs and molecular gas masses is still subject to major uncertainties. The existence of two different modes for star formation (SF) has recently been questioned - this finding depends on the usage of two different conversion factors from CO luminosity to molecular gas mass. I investigate and compare the optically thin emission from the dust continuum at 850 micron and carbon monoxide (CO) ground state rotational transition J=1 -> J=0 emission as tracers of molecular gas. I analyse several samples of galaxies from the literature spanning different locations with respect to the main sequence (MS) of SF through cosmic time (z=0-6). The different galaxies have a remarkable correlation between the two quantities, which indicates no strong difference in the CO conversion factor between local disc galaxies and ULIRGs. However, differences of about a factor 3-4 between galaxies at high redshift situated on and above the MS are seen. I investigate the discrepancies observed also taking into account differences in metallicity, SFR and tracers of shock heated gas in galaxies. There are only mild relations found between these quantities and the ratio of dust continuum to CO(1-0) line emission, so possibly other physical parameters are the drivers of the differences. [Referees: Prof. Dr. Karl Menten, Prof. Dr. Frank Bertoldi, Advisor: Dr. Axel Weiß]

	Lunch Colloquium
Dr. Eleni Vardoulaki	ORATED

AIfA

I will present an analysis on the radio structure of radio sources from the VLA-COSMOS 3GHz Large Project (JVLA COSMOS; Smolcic et al. 2016 in press). These objects were selected from the JVLA COSMOS field on the basis of their extended radio structure, associated with radio AGN, and were placed in radio classes based on the FR-type classification of Fanaroff & Riley (1978). The purpose of this project is to compare the radio structure of radio AGN to the more fundamental division between accretion properties of the black hole, i.e. radiatively efficient and inefficient accretion, and to understand the reason for the existence of different FR types; whether it is due to the energetics or due to environmental effects. For the latter, I use the X-ray groups in the COSMOS field (George et al. 2010) as a parameter for the environment, to investigate trends of FR-type radio structure with group environment. Finally, I will present preliminary results on an automatic (semi-supervised) method to classify radio sources with complex radio structures in radio surveys.

	Main Colloquium
Prof. Dr. Manel Perucho	ORATED

Universitat de València, Spain

I will review recent results on the internal structure of relativistic, magnetized jets, from RMHD simulations. The first part of my talk will focus on the derivation of equilibrium models for axisymmetric, rotating jets. In particuar, I will discuss the influence of the toroidal magnetic field on the jet structure through magnetic pressure and tension, and that of the rotation pattern via the centrifugal force. The equilibrium models obtained were later used as an initial setup to study the structure of steady, overpressured jets, by means of numerical simulations. We have run a number of such simulations for superfast magnetosonic jets. The injection parameters of these jets were chosen to cover a wide region of the parameter space across a temptative fundamental plane of magnetized jets, given by their magnetosonic Mach number versus specific internal energy. This selection includes also a wide range of magnetizations. The results of the simulations will be discussed in terms of the dominant energy in the jet (internal, kinetic, magnetic). I will finally propose observational tests that can help us to obtain information about the dominant energy channel in extragalactic jets, and discuss future lines of research in this field.

	Special Colloquium
Dr. Akimasa Kataoka	ORATED

ITA, Heidelberg University

Constraining the grain size in protoplanetary disks is a key to understand the first stage of planet formation. The grain size has been estimated by measuring the spectral index at millimeter wavelengths, while it has huge uncertainties. Here, we propose that millimeter-wave polarization is another method to constrain the grain size. We show that thermal dust emission is scattered off of other dust grains and the residual polarization is up to 2.5 %, which is detectable with ALMA. This self-scattering polarization is most efficient if the maximum grain size is comparable to the wavelengths. Therefore, we can constrain the grain size from millimeter-wave polarization of protoplanetary disks. Furthermore, we have observed the protoplanetary disk around HD 142527 with ALMA polarization mode, and found the evidence that the self-scattering plays a role in the protoplanetary disk.

	SFB Colloquium
Dr. Alexis Finoguenov	ORATED

U Helskinki

After an introduction to X-ray selection of galaxy groups in deep fields, I will review the results on the galaxy evolution and AGN triggering in massive environments. I will conclude that star-formation and tidal interactions are the two dominant processes, that describe our observations between now and a redshift of 2.5. Triggering of AGN activity is governed by the same processes and serves as a sign-post of galaxy transformation.

	Lunch Colloquium
Silvia Leurini	CANCELED

MPIfR Bonn

The mechanisms leading to the formation of disks around young stellar objects and to the launching of the associated jets are crucial to the understanding of the earliest stages of star and planet formation. However, while fast collimated jets are commonly observed in very early phases of evolution, the evidence of disks in these stages is not clear probably due to the expected small size of the disks and to the fact that in these still deeply embedded objects the emission of the surrounding envelope is likely entangled with that of the disk. In this talk, I will report ALMA observations of HH212, a protostar driving a strikingly bipolar H_2/SiO collimated jet. The ALMA-Band 7 data trace all the crucial ingredients involved in the star-disk formation recipe in unprecedented detail, and within a single spectral set-up: (i) the dusty protostar; (ii) the axial jet launched from it; (iii) the biconical outflow and its cavities; (iv) the parent infalling envelope; (v) the forming disk.

	Main Colloquium
TBD TBD	CANCELED

TBD

TBD

	Main Colloquium
Dr. Agnes Kospal	ORATED

Konkoly Observatory, Budapest, Hungary

A long-standing problem of the general paradigm of low-mass star formation is the "luminosity problem": protostars are less luminous than theoretically predicted. One possible solution is that the accretion process is episodic. FU Orionis-type stars (FUors) are thought to be the visible examples for objects in the high accretion state. FUors are often surrounded by massive envelopes, which enable the disk to produce accretion outbursts and replenish the disk material. However, we have no information on the envelope dynamics, about where and how mass transfer from the envelope to the disk happens. Here, we present continuum and CO line observations of the young eruptive star V346 Nor obtained by ALMA. Our goal is to study the structure of the circumstellar matter and the infall process from the envelope onto the disk in a highly accreting system. The infall rate is a little known input to estimate the incidence of FU Orionis-type outbursts, a key parameter determining whether FUors offer a solution for the luminosity problem.

	Informal Colloquium
MSc Tomonari Michiyama	ORATED

ALMA Division, National Astronomy Observatory of Japan

I introduce the Japanese telescope ASTE and AKARI, and review the Michiyama et al. 2016 (http://ads.nao.ac.jp/doi/10.1093/pasj/psw087), which investigate the relation between the CO(3–2) luminosity and the far Infrared luminosity a sample of 29 early stage and 31 late stage merging galaxies, and 28 nearby isolated spiral galaxies. Comparing our results with sub-kpc scale local star formation and global star-burst activity in the high-z Universe, we discuss how the merging galaxies affect the star formation relation. In addition, I show our recent ALMA Cycle 3 results of molecular line survey towards a late stage merging galaxy NGC3256. We have detected 24 molecules at 2” angular resolution, which is high enough to resolve the double nuclei. ALMA open new eye for chemical evolution during galaxy and galaxy merger.

	Lunch Colloquium
Dr. Gregory Desvignes	ORATED

MPIfR

PSR J1906+0746 is a young relativistic binary pulsar in a 4-hr orbit, most likely around another neutron star. We report here on the observation of relativistic spin precession, an effect known to occur when the pulsar spin axis is misaligned with respect to the orbital angular momentum vector. Modelling the polarimetric data recorded with the Arecibo and Nancay radio telescopes, we determine the geometry of the pulsar and present two additional tests of General Relativity for this system. As the pulsar precesses, the observer line of sight crossed the magnetic pole for the first time, allowing us to derive unprecedented 2-D emission beam maps that we can trace back to the pulsar magnetosphere. These results will help to constrain the poorly-known radio emission physics and revise the beaming fraction of pulsars.

	Promotionskolloquium
Naftali Kimani	ORATED

MPIfR

The 3-D velocity of galaxies relative to the Milky Way are a powerful tool for a better kinematic model of the Local Volume. The 3-D velocity is derived by combining the radial velocity and the proper motion. The radial velocity is easier to derive from the Doppler effect, while the proper motion is both difficult and a time consuming. In this thesis, we derive the proper motion of M81 and M82 galaxies, both members of M81 group, using the phase-referencing technique. These are the first-ever proper motion measurements of galaxies outside of the local group. The results besides being important in making a better kinematic model, they are important initial parameters for accurate modeling of the M81 group interaction, providing a better understanding of the dynamics and consequence of tidal interactions in a group environment. Moreover, in the course of proper motion observations, a radio supernova SN2008iz exploded in M82 galaxy. After the discovery, a multi-frequency monitoring campaign was initiated to enable a detailed study of the supernova. Using the data, we studied the evolution of the supernova remnant using both the light-curve and the high-resolution VLBI images. We also studied how the shock-wave evolved by estimating the shell radius, the deceleration index and the spectral indices. [Referees: Prof. Dr. Karl. M. Menten (MPIfR); Prof. Dr. Pavel Kroupa (HISKIP); Prof. Dr. Ian C. Brock (Physikalisches Institut); Prof. Dr. Hubert Schorle (Institute of Pathology) ]

	Main Colloquium
Prof. Monica Colpi	CANCELED

University of Milano Bicocca

TBD

	Special Colloquium
Dr Chat Hull	ORATED

Harvard-Smithsonian Center for Astrophysics/ NRAO

Understanding the role that the magnetic field plays in the formation of stars is one of the most pressing questions in galactic astronomy, and one that is far from settled. Because the magnetic field in the interstellar medium is "frozen" into the dust and gas, strong magnetic fields have long been thought to be the dominant regulator of star formation, having implications for star formation on every scale, from the clouds out of which they coalesce to the circumstellar disks where planets form. With the advent of high-resolution observations of dust polarization with interferometers such as BIMA, OVRO, SMA, CARMA, VLA, and now ALMA, the field of protostellar magnetic fields has been blown wide open, yielding results that continue to tantalize and confound. I will review SMA and CARMA results from the past decade that have shown both hallmarks of the "strong-field" star formation scenario (such as "hourglass" magnetic field morphologies) as well as hints that there may be a mode of star formation where the magnetic field is not the dominant dynamical player (i.e., cases where outflows and magnetic fields are misaligned, contrary to theoretical expectations). I will then move on to show new ALMA polarization data and next-generation AREPO simulations that suggest that in all but the most strongly magnetized clouds it is cloud-scale turbulence -- not the large-scale magnetic field -- that dictates the magnetic field morphology immediately surrounding a protostar. I will conclude with a look to the future, when the highest-resolution ALMA polarization observations will be sensitive not only to magnetic fields, but also to dust scattering, giving us access to additional physics in the planet-forming disks around young protostars.

	Main Colloquium
Dr. Marcel Pawlowski	ORATED

Hubble Fellow, University of California, Irvine

TBD

	Special Colloquium
Prof. Judith Irwin	ORATED

Queen's University at Kingston, Canada

Circular polarization is technically difficult to measure in astrophysics, due to the weakness of the signal. Very few sources have had confirmed circularly polarized signals, but the scientific payoff can be significant, especially the potential insight that such observations provide on the nature of Active Galctic Nuclei. This talk will review observations of circular polarization in nearby systems, as well as present some new results from CHANG-ES (Continuum Halos in Nearby Galaxies -- an EVLA Survey). A close look at circular polarization is especially timely now that we are approaching the era of the Square Kilometre Array.

	Lunch Colloquium
Dr. Alan Roy	ORATED

MPIfR

Enormous areas of solar concentrators are being constructed around the world due to the growing global investment in renewable energy. Their surface accuracies would allow operation at gigahertz frequencies and those in the form of solar power towers form a point focus convenient for installing a radio receiver and presently four square kilometres of collecting area are operating which could give us a cost-effective way to achieve SKA phase 2 sensitivity. We have made progress understanding how one might combine signals from such a mirror field to form a single dish or interferometric array even though the mirror field does not lie on a parabola and the signals sum incoherently in the focal plane to produce a speckle pattern. I will give an update on how the focal plane speckle appears in simulations and how a beamformer might work. The next step needed is a proof-of-concept on the sky with a focal plane array on the Juelich solar power tower. Coauthors: O. Wucknitz & I. Cámara-Mayorga

	Special Colloquium
Dr. Nissim Kanekar	ORATED

National Centre for Radio Astrophysics, India

Damped Lyman-alpha Absorbers (DLAs) are the high-redshift counterparts of today's normal gas-rich galaxies, with high HI column densities, N_HI >= 2e20 per cm^2. Despite their acknowledged importance in the context of galaxy evolution and thirty years of research, the nature of high-redshift DLAs remains an open issue, primarily due to the difficulty in identifying their host galaxies. In this talk, I will present results from a slew of new radio and optical studies aimed at characterizing DLA host galaxies, via measurements of their atomic and molecular gas masses, their velocity fields, and their star formation rates. Finally, I will discuss implications of our studies for the nature of DLAs, and their relation to other high-redshift galaxy populations.

	Main Colloquium
Dr Richard Wunsch	ORATED

Astronomical Institute, Czech Academy of Sciences

We present a model of fast cooling stellar winds in young massive clusters and estimate the circumstances under which the secondary star formation occurs. If the cluster is massive and compact enough, the shocked stellar winds become thermally unstable, collapse into dense gaseous structures that partially accumulate inside the cluster, self-shield against ionizing stellar radiation and form the second generation of stars. 3D radiation hydrodynamic simulations enable us to calculate the mass of the second stellar generation. Furthermore, they predict that with reasonable parameters, second generation stars form only in the very centre of the cluster. The recombination line emission from the warm gas accumulated in the cluster estimated from simulations shows that the model could be tested e.g. by observing super star clusters in interacting galaxies NGC4038/9 (Antennae) using ALMA. We suggest that a similar mechanism can be responsible for the origin of multiple stellar populations found in globular clusters.

	Lunch Colloquium
Prof. Rosa Gonzalez	ORATED

Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Mexico

We aim to explore the relationship between the total number of globular clusters, N_GC, and the mass of the central black hole, M_BH, in spiral galaxies, and how it compares with that recently reported for elliptical galaxies. We present results the globular cluster system of the S_bc galaxy NGC 4258, from u*, g', i', r', and K_s data obtained with the Canada France Hawaii Telescope. Thanks to water masers in a circumnuclear disk, the absolute distance to NGC 4258 has been derived directly by geometric means, and hence has the most precisely measured extragalactic distance and supermassive black hole mass to date. We directly identify 38 GC candidates; after completeness correction, GC luminosity function extrapolation and correction for spatial coverage, we calculate a total NGC = 166±39(+44/-42) (random and systematic uncertainties, respectively) for NGC 4258. We have thus increased to 6 the sample of spiral galaxies with measurements for both M_BH and N_GC. NGC 4258 has a specific frequency SN= 0.45±0.15 (random uncertainty), and it is consistent within 2 sigma with the N_GC vs M_BH correlation followed by elliptical galaxies. The Milky Way continues to be the only spiral that deviates significantly from the relation.

	Informal Colloquium
Prof. Eduardo Ros	ORATED

MPIfR

As elected member of the scientists of the MPIfR to the Chemistry-Physics-Technology Section (CPTS) of the Scientific Board of the Max Planck Society, I will report to the electors about the last news and trends in the Society after regular meetings in October, February, and June. This is part of our mandate as elected representatives. The last meeting of the CPTS took place at the MPS Harnack-Haus in Berlin-Dahlem on October 20-21, 2016, together with a workshop and a Harnack lecture on gravitational waves. An informal, short summary on the main points raised the meeting followed by a discussion will be offered. Note: This is a MPIfR internal meeting

	Lunch Colloquium
Dr. Wolfgang Reich	ORATED

MPIfR

In 1956, polarized emission from Tau A was detected, which unambigously proves that SNRs emit synchrotron radiation. SNRs are the primary sources of cosmic-rays. During the last 60 years, a large number of polarization data were collected for shell-type SNRs and PWNs. Radio data reveal the morphology and direction of the regular magnetic field component and the fraction of the turbulent field. Reliable estimates of the magnetic field strength require at most additional information on cosmic-ray or thermal gas density or a spectral bend. The vast majority of the about 300 known Galactic SNRs and PWNs from the expected 1000 objects was identified by radio observations. The current detection rate is 4 to 5 new objects per year with a very low surface brightness. Recent Effelsberg polarization observations of a new faint and large SNR indicate a promising SNR search strategy free from confusion effects.

	Main Colloquium
Dr. Diego Blas	ORATED

CERN

The high quality of the data coming from pulsar timing makes of it a fantastic resource to understand gravitational phenomena. Traditionally this has been used to test general relativity and alternative theories of gravity. In this talk I plan to focus on a less known possibility: using pulsar timing to understand dark matter properties. I will discuss (possibly) detectable modifications of binary orbits due to the interaction with the dark matter and of the propagation of the radio signal.

	Lunch Colloquium
Dr. Sambaran Banerjee	ORATED

AIfA

Black holes in dense stellar clusters such as globular clusters have always drawn attention due to their potential in a number of interesting astrophysical phenomena. And at present, the interest has rejuvenated due to the first direct detection of gravitational waves from a couple of merging black hole binaries, by the Advanced LIGO detector. Such “stellar-mass” black holes are end products of high-mass (O-type) stars, and a fraction of them can potentially remain trapped in a stellar cluster by the latter’s deep gravitational potential, where they would interact. In this talk, I will introduce the dynamical behaviour of such a trapped and densely-packed system of black holes; in particular, how it acts as an “engine” for generating binary black holes, which are capable of merging via gravitational-wave inspiral, and how it influences the parent cluster’s structure and evolution. Following the lines of a well-noted earlier work by Banerjee et al. (2010), I will present my recent and much more detailed direct N-body calculations that take into account the contemporary knowledge of black hole formation from high-mass stars. These calculations indicate that regular young, intermediate-mass and open star clusters, that continue to form and evolve in late-type gas-rich galaxies (e.g., spirals, starburst), as well serve as environments for generating binary black hole inspirals, like old massive globulars, especially when it comes to subsolar metallicities.

	Promotionskolloquium
Alice Pasetto	ORATED

MPIfR

In this Thesis I present an observational study of a sample of radio AGN sources. I study their radio polarization properties in a wide frequency range by observing with the 100-m Effelsberg telescope and the Very Large Array (VLA) interferometer. The aim was 1) to define a sample of candidates to contain an extreme environment around the SMBH and, 2) to study their environment by modeling of the polarization properties within a wide frequency range. I select sources with no detectable flux polarization at 1.4GHz in the NVSS survey, characteristic of strong depolarization due to a high value of Rotation Measure (RM) and thus, of an extreme medium in these sources. I performed single dish observations at 10.45 GHz using the 100-m Effelsberg telescope. At this high frequency, I detected polarized flux density on 30 sources, which became our high-RM candidates. Single dish follow-up in the 2 to 15 GHz frequency range, were performed to characterize their radio spectra and to determine their RMs. The polarization angle behavior deviates significantly from the lambda^2 law, suggesting that several Faraday screens are present in the intervening medium. I studied the most interesting high-RM cases through wide-band high sensitive observations at C and X bands using the JVLA. I modeled the polarization properties constructing a set of models which are combinations of simple internal and the external Faraday screens. This new approach of polarization study allows to spectrally resolve multiple polarized components of unresolved AGN with the result to trace some clumpy and dense region surrounding them. This new spectropolarimetry approach can be adopted as a new way to trace clumpy and dense regions surrounding the AGN. [Referees: Prof. M. Kramer; Prof. T. Reiprich; Prof. M. Drees; Prof. B. Kirchner]

	Main Colloquium
Dr Oliver Porth	ORATED

Institute for Theoretical Physics, Frankfurt

Upcoming mm-VLBI observations will probe the SMBH in our galactic center and the giant BH in M87 on the horizon scale. While both objects accrete in a similar, highly sub-Eddington regime, only M87 shows clear evidence for a persistent relativistic jet. In anticipation of direct observations of the jet (non-) formation site, I will discuss the state of the art of GRMHD jet formation models focussing on presence or absence of a jet, intrinsic variability and the accretion/ejection efficiency. While great progress has been made to understand how a once formed jet accelerates and collimates in the framework of dissipation-free magnetohydrodynamics, several key questions remain unsolved. Among these are the problem of inefficient ideal MHD acceleration, the question of how material is loaded and entrained in the jet and the puzzle of the often remarkable jet integrity. Recent idealized simulations on 3D instabilities and jet causality shed some light on these issues: dissipation due to internal kink- instabilities can aid in the jet acceleration while keeping the integrity intact. The ambient medium plays a crucial role in the evolution of the jet: Cosmic jets may become globally unstable when they enter flat sections of external atmospheres. I propose that the Fanaroff–Riley (FR) morphological division of extragalactic radio sources into two classes is related to this issue.

	Lunch Colloquium
Dr. Emmanouil Angelakis	ORATED

MPIfR

We are presenting the highlights of the R-band polarization program RoboPol that has been monitoring a sample of gamma-ray-loud (GL) and one of gamma-ray-quiet (GQ) sources with cadence of days. We discuss both the amplitude domain as well as the angle domain findings. Motivated by the discovery that blazars occasionally display smooth and long rotations of their optical polarization plane, we designed, funded, constructed and are operating a 4-channel optical polarimeter for the systematic study of the phenomenon. The program has already completed its first 3 observing seasons with the monitoring of an unbiased sample of 65 GL taken form a flux-limited sub-set of 2FGL and 15 GQ sources selected from the 15-GHz OVRO monitoring program. The main goals of the program has been: (a) the temporal behavior of the polarization of blazars; (b) the quantification of the polarization parameters of GL sources and the search for possible systematic differences with those of GQ sources; (c) the systematic study of the polarization angle rotations and their association with the activity MeV – GeV energy band, and the search for possible physical connection between them. Some findings that will be discussed; Amplitude domain : we discover that GL sources are more polarized (as a population) than GQ ones, at a level beyond the 3 sigma. We also find that the higher the SED synchrotron peak frequency the lower the polarization and its variability. We also find that the polarization angle seems to be more stable with increasing peak frequency which implies a helical topology of the field to be dominant. The polarization shows a positive correlation with the flux density variability while a negative one with polarisation the variability. Angle domain: we find that the brightest gamma-ray flares tend to be closer in time to rotation events, an indication that two separate mechanisms produce rotations. We show that it is unlikely that all the observed rotations are produced by random walk of the polarization vector. Additionally it is highly unlikely that none of our rotations is physically connected with an increase in gamma-ray activity. The average fractional polarization during the rotations tends to be lower than that in a non-rotating state. The average fractional polarization during rotations is correlated with the rotation rate of the polarization plane in the jet rest frame.

	Lunch Colloquium
Prof. Karl Menten	ORATED

MPIfR

Since 10 years, the Atacama Pathfinder Experiment Project (APEX) has been operating a 12 m diameter telescope on a 5100 meter altitude site in the Chilean Atacama desert. APEX has opened the southern skies for submillimeter wavelength astronomy, centering on dust and molecules throughout the Universe. APEX has made a series of exciting, unexpected discoveries. Large surveys of dust emission over the whole southern galactic plane and deep observations of cosmological Deep Fields have provided unbiased views of star formation in the Milky Way and at high redshift. In comprehensive follow up programs with APEX itself, but also with other observatories and at other wavelengths, the nature of the sources found in these surveys is investigated. A continuous line of state of the art, highly innovative detectors gives APEX full coverage of all the submillimeter windows accessible from the ground for spectroscopy and matchless wide area imaging capability for continuum radiation that will soon be expanded enormously. APEX has been a pathfinder not only for the recently completed Atacama Large submillimeter/ Millimeter Array (ALMA), but also for Herschel and the Stratospheric Observatory for Infrared Astronomy (SOFIA). After an overview of APEX including its instrumentation, key science results will be presented together with an outlook for the coming years – the Max-Planck-Society has just decided to extend the project until 2022.

	Lunch Colloquium
Kevin Harrington	ORATED

AIfA

The Cosmic Infrared Background consists of the epoch where the majority of the stars we see today were formed (1 < z < 3.5), and in this talk I will present Planck's all-sky survey ability to pick out some of these most luminous sources. I present the confluence of Herschel's higher angular resolution to partially resolve Planck point sources to identify dusty star-forming galaxies (DSFGs). As well, I present one of the pioneering publications of the Early Science Campaign with the Large Millimeter Telescope's single-dish sensitivity, 1.1mm camera (AzTEC) and broad bandwidth spectrometer (the Redshift Search Receiver: 73-111GHz) in successful target follow-up to begin characterizing the ISM and gas properties of these luminous sources with L_IR > 10^(13-14) L_sun.

	Lunch Colloquium
Dr. Xinping Deng	ORATED

MPIfR/ATNF

The first characterization, commissioning, calibration and pulsar observation of a Phased Array Feed (PAF) on the 64-m Parkes radio telescope will be presented. This is the first time a PAF has been installed on a large single-dish radio telescope. The PAF will be installed on the 100-m dish at Effelsberg after a 6-month trial observing program at Parkes. I will give an overview on the project and PAF system first and then describe all commissioning tasks toward novel astronomical observations. These tasks include 1) physical installation of the PAF and 2) sensitivity measurement and beamforming using point radio source, etc. I will also present the first pulsar timing observations with the PAF. These observations demonstrate that 1) multiple pulsars (in FOV) can be observed simultaneously, 2) it is possible to polarisation calibrate the pulsars at any position in the FOV and 3) pulsars can be observed over relatively long integration times even though the PAF is unable to rotate. I will give update on Mark III PAF “rocket” at the end of my talk. ​

	Main Colloquium
Dr. Lorenzo Sironi	ORATED

Harvard CfA

The quiescent emission spectrum of the Crab nebula, extending from the radio up to the gamma-ray band, is usually modeled as synchrotron and inverse Compton radiation from a non-thermal population of electron-positron pairs. By means of 2D and 3D first-principle particle-in-cell (PIC) simulations, we investigate particle acceleration and magnetic field dissipation at the termination shock of a “striped” pulsar wind, where the sign of the pre-shock field alternates with the pulsar period. At the shock, the alternating fields annihilate by driven magnetic reconnection, resulting in a hard power-law tail of non-thermal electrons with slope between -1.5 and -2, as required for the Crab nebula quiescent radio emission. In addition, we show with 2D and 3D PIC simulations that explosive magnetic reconnection in the nebula might explain the unusually short durations, high luminosities, and high photon energies of the gamma-ray flares recently detected from the Crab Nebula by the AGILE and Fermi satellites.

	Lunch Colloquium
Dr. Christopher Morrison	ORATED

AIfA

Estimating the redshift or equivalently the distances to extra-Galactic objects is crucial for interpreting their properties and using them to measure cosmology. Redshifts are best confirmed spectroscopically however, for wide, deep surveys and simillarly for faint objects the telescope time required for a spectroscopic confirmation is prohibitive. Faint objects often have their redshift estimated from board band pass filters through photometric redshifts however these techniques require a representative set of spectra to calibrate them which can also be prohibitive. A complementary technique is to use spatial cross-correlations between a sample of objects with known redshifts to estimate and the sample of interested with unknown redshifts to estimate their redshift distribution. These clustering redshifts (cluster-zs) can be extremely powerful for galaxy samples without a representative, calibration sample and can use samples such as high redshift QSOs to estimate galaxy redshifts. I will present clustering redshift estimates of the wide-area, deep Kilo Degree Survey (KiDS) using reference spectra from the Sloan Digital Sky Survey (SDSS) and the Galaxy and Mass Assembly (GAMA) survey. I also present a unique method for estimating clustering redshifts for single galaxies instead of a large sample.

	Special Colloquium
Prof. Dimitrios Giannios	ORATED

Purdue University

Relativistic jets, i.e., collimated flows of plasma that move at a speed close to the speed of light, are a common manifestation of accreting black holes. When the jet from a supermassive black hole moves close to our line of sight, it makes a "blazar". Blazars are spectacular sources that outshine the host galaxy, show extremely bright, broadband flares on timescales as short as minutes and make prime candidates for accelerating ultra-high-energy cosmic rays. The common hypothesis for jet formation is that they are launched by powerful magnetic fields that thread the black hole and the inner accretion disk. After reviewing our ideas of how the magnetic fields make it to the source, I discuss the trip of the jet from the central engine to the much larger scales where it radiates. I argue that the jet emission is result of dissipation in the jet through the process of magnetic reconnection. I will review our latest understanding of the physics of magnetic reconnection and show how it can account, from first principles, for the “emitting blobs” commonly invoked when modeling the blazar flares.

	Main Colloquium
Prof. Ulrik Uggerhoej	ORATED

Department of Physics and Astronomy, Aarhus University

Utilizing the relativistic invariance of the parameter χ=γE/E0, ultrarelativistic particles in strong crystalline fields of the order 10^11 V/cm enable investigations of processes in fields of the order the QED critical field E0=m^2c^3/eħ=1.32·10^16 V/cm (with a corresponding magnetic field of B0=4.41·10^9 T) in the particle rest frame. In the framework of the CERN NA63 experiment we have obtained experimental results on e.g. quantum synchrotron radiation emission, trident production and coherent pairs in such fields, as well as observing effects related to the mesoscopic photon formation zone. Apart from their relevance to astrophysical emission processes as e.g. taking place at neutron stars, and relevance to the fields encountered in heavy ion collisions, these studies are important for the design of the interaction point of future high energy colliders. Last, but not least, many of the processes studied are relevant in the context of intense laser fields, as e.g. aimed to be investigated at the Extreme Light Infrastructure (ELI).

	Special Colloquium
Dr Jeroen Stil	ORATED

Calgary

Outside the Galactic plane we can investigate small-scale structure in the interstellar medium without confusion with unrelated structure in the background. Faraday rotation of polarized extragalactic sources reveals structure with angular scales up to tens of degrees in angular size far from the Galactic plane. Interpretation of the observed Faraday rotation is challenging without an appropriate model for the electron density distribution. I will discuss recent results and new data from the GALFACTS survey (Arecibo) for a 35-degree-long ionized intermediate-velocity filament to discuss what we can learn about these high-latitude measurements. Specifically, I will discuss a lower limit to the Alfven velocity derived from rotation measure and emission measure that indicates that this filament has a plasma beta < 1 (gas pressure over magnetic pressure).

	Special Colloquium
Sarah Leslie	ORATED

MPIA

Multiwavelength studies have revealed that star forming galaxies typically exhibit a current star formation rate proportional to their assembled stellar mass forming a main-sequence in the star formation rate-stellar mass plane. Using 200,000 local galaxies at 0.04 < z < 0.1 in the Sloan Digital Sky Survey we have classified galaxies (into different activity classes: star forming, AGN) according to their emission line ratios. We find that these different classes occupy specific regions in the star formation rate - stellar mass plane: galaxies show a trend from the `blue cloud' galaxies which are actively forming stars, through a combination of composite, Seyfert, and LINER (Low-ionization nuclear emission-line region) galaxies (through the green valley), ending as 'red-and-dead' galaxies. This observational trend supports an evolutionary pathway for galaxies in which star formation quenching by active galactic nuclei (AGN) plays a key role. We then look at the position of star-forming disc galaxies SFR-stellar mass plane as a function of galaxy inclination. By measuring the attenuation of light at different wavelegnths for inclined galaxies, we can probe the global dust properties. We compare our local results to a sample of discs at z~0.7 in the COSMOS field. We find that the inclination effects due to dust extinction are the same at z~0.7 as they are locally, indicating that there is no evolution in dust properties between z=0 and z=0.7.

	Lunch Colloquium
Dr. Walter Max-Moerbeck	ORATED

MPIfR

A complete understanding of the physics blazars requires monitoring observations over the whole electromagnetic spectrum, and includes studying their properties at a given band and also the relationship between multiple wavelengths. Here I present the main results obtained so far with the ongoing OVRO 40m blazar monitoring program at 15 GHz with twice a week cadence. This program started in mid-2007 and is currently monitoring about 1800 blazars, including most of the bright blazars north of declination -20 degrees. These results include: characterization of the variability in the radio band; its relationship with optical and gamma-ray properties; and its relationship to gamma-ray emission as observed with Fermi-LAT, which can provide constrains on the location of the gamma-ray emission region. I will also discuss our ongoing work on the characterization of radio variability using the power spectral density. For this, we are using 8 years of OVRO 40m data for ~1200 sources, and also F-GAMMA monitoring data taken with the Effelsberg 100m telescope for 60 sources with about monthly cadence monitoring data at 8 frequencies between 2.6 and 43.0 GHz. These studies will provide an improved understanding of blazar variability, a better basis to evaluate the statistics of correlated variability between different emission bands, and a long and consistent record of radio observations to be used in gamma-ray and multi-wavelength investigations.

	Main Colloquium
Prof. Jim Hinton	ORATED

MPI, Heidelberg

CTA is an international effort to implement the first proposal-driven open observatory for the highest energy photons. Building on the success of current very high energy gamma-ray telescopes such as HESS, CTA will help us to understand the origin of relativistic cosmic particles and their role in the evolution of star forming systems and galaxies, allow us to probe extreme environments such as those around neutron stars and black holes, but also the cosmic voids, and explore frontiers in physics, including the nature of dark matter. CTA construction is expected to start next year. In this talk I will discuss the scientific motivations for CTA and synergies with other wavebands as well as the plans for implementing the Observatory.

	Lunch Colloquium
Felipe Navarete	ORATED

Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Brazil

In the past years, astronomy has evolved from the usage of spectroscopic and imaging techniques, operated separately, to more modern data acquisition methods that combining both techniques simultaneously, producing images with spectral resolution. Here, I will show a method of analysis of datacubes (data containing two spatial and one spectral dimension), developed at University of São Paulo (USP/Brazil), that uses PCA (Principal Component Analysis) to transform the system of correlated coordinates into a system of uncorrelated coordinates ordered by principal components of decreasing variance. The new coordinates are referred to as eigenvectors, and the projections of the data onto these coordinates produce images we will call tomograms. The association of the tomograms (images) to eigenvectors (spectra) is important for the interpretation of both. By handling eigenvectors and tomograms one can enhance features, extract noise, extract spectra, etc. I will show a few examples of the applicability of the PCA Tomography, that has shown very promising results in scales ranging from AU to kpc by identifying circumstellar disks around young stellar objects and probing the content of galaxies in the Local Universe.

	Main Colloquium
Prof Kenji Bekki	ORATED

ICRAR, Perth

Globular clusters (GCs) have long been considered to be single stellar populations (SSPs) - collections of coeval and chemically homogeneous stars. Recent photometric and spectroscopic observations, however, have revealed that most of the Galactic GCs contain at least two different stellar populations with difference chemical abundances, and possibly, different ages. I will discuss the following three topics related to this recent discovery of multiple stellar populations of GCs. First, I will show our new observational results on the presence of multiple-generation of stars in star clusters of the Large Magellanic Cloud. Second, I will show the results of numerical simulations on the two-stage formation process of GCs in gas-rich dwarf disk galaxies. Third, I will discuss how the 'anomalous GCs' with metallicity spreads can be formed within their host galaxies using our latest simulations of GC merging.

	Special Colloquium
Dr. Bi-Qing For	ORATED

ICRAR

The Magellanic Stream and Leading Arm which originated from the Magellanic Clouds are spectacular gaseous features. They extend for tens of kpcs and span for ~200 degree in the southern sky. The close proximity of the Magellanic Clouds to the Milky Way provides an excellent opportunity to study interacting galaxy system. I will present the results of a study of High-Velocity Clouds (HVCs) in the Magellanic Stream and the Leading Arm. The properties of HVCs in the two regions are compared and contrasted in order to study the different mechanisms shaping their structure and evolution. I will also present potential studies using Australia SKA Pathfinder.

	Main Colloquium
Dr Markus Böttcher	ORATED

Ohio University

Diffusive Shock Acceleration (DSA) as a form of first-order Fermi acceleration has long been considered one of the leading contenders for the acceleration of electrons to ultrarelativistic energies in the jets of active galactic nuclei (AGN). I will present the results of a systematic study of the radiative signatures of DSA in blazar jets. Based on fits to the spectral energy distributions of blazars, one can infer characteristics of the hydromagnetic turbulence mediating DSA, specifically a strongly energy-dependent mean-free-path for pitch-angle scattering. I will also present a consistent treatment of particle dynamics and polarization-dependent radiation transfer in an internal-shock model for blazar jets, which explains large polarization-angle swings, correlated with multi-wavelength flaring activity, without the need for non-symmetric jet features.

	Special Colloquium
Dr. Mubdi Rahman	ORATED

Department of Physics and Astronomy, Johns Hopkins University

Understanding the process of energetic feedback from star formation requires comprehensive exploration of both the stellar and gaseous components of star forming complexes. The diversity of scales probed make conducting such studies difficult in extragalactic systems. The Milky Way provides an excellent opportunity to explore feedback processes in detail, albeit with a unique set of challenges. In this talk, I will be discussing our current strides in measuring and analyzing feedback from massive star formation in the Milky Way.

	Main Colloquium
Dr Amanda Karakas	ORATED

ANU

Low and intermediate stars (1 to 8 solar mass) are an important sources of gas and dust in the Galaxy today. Most of the mass is lost while stars are on the Asymptotic Giant Branch (AGB), with dust formation occurring in the extended envelope surrounding the star. Ancient meteorites harbour a tiny fraction of pre-solar dust grains, which formed in the outflows and remnants of evolved stars such as AGB stars. Pre-solar grains are particularly important because they can be used to test our understanding of stellar evolution and nucleosynthesis. The majority of carbonaceous pre-solar grains likely formed in the extended envelopes of low-mass AGB stars (1-4 solar mass), although other sources include supernova and nova explosions. In this talk I will focus on a couple of examples including using silicon carbide (SiC) grains to test models of the slow neutron capture process, and I’ll discuss a possible stellar source for the A+B grains, which are a type of SiC grain whose origin is still unclear. I will also discuss how merged binary stars may be an unrecognized source of carbon-rich stardust.

	Special Colloquium
Honey M.	ORATED

Indian Institute of Astrophysics

We present the results of our near infrared (NIR) imaging study of barred Low Surface Brightness (LSB), their 2D disk decomposition using optical images and how their bar morphologies vary with central disk velocity dispersion. LSB galaxies are extreme late type galaxies that have low luminosity stellar disks but large, neutral hydrogen (HI) gas disks . They are poor in star formation and are dark matter dominated systems. Bars are not common in halo dominated disk systems. Using a large sample of LSB galaxies from the literature, we found that the fraction of barred LSB galaxies is only ~ 8.3% . Using our NIR images, we examine their bar morphology, to see the properties of bars in the dark matter dominated systems and how they differ from normal galaxies. Our analysis of the NIR images shows that the bars in LSB galaxies are similar to those found in normal galaxies. To get a more accurate picture we did the 2D disk decomposition of their optical images. We find that most of the LSB barred galaxies have bulges that are oval or boxy in shape; this suggests that there is slow internal evolution occurring in these systems. We also examined their central velocity dispersion using their optical nuclear spectra, which can tell us about the central mass concentration in these galaxies. We examined how this varies with bar ellipticities. We compare our observations with simulations of bar formation in dark matter dominated galaxies and discuss the implications of our results.

	Promotionskolloquium
R. Nicolas Caballero	ORATED

MPIfR

Pulsars are highly magnetised neutron stars which spin tremendously fast, at periods that are as low as a few milliseconds. Their periodic signals reach us when the beamed emission from their magnetic poles, which sweeps space, crosses our line-of-sight. Due to their remarkable rotational stability, millisecond pulsars (MSPs), the fastest-rotating pulsar population, are used as cosmic clocks to probe the curvature of space-time and study the nature of gravity in regimes that cannot be tested in the Solar system. In this talk, I will first explain the pulsar-timing method and its applications. I will proceed with a discussion on how an ensemble of MSPs, known as a Pulsar Timing Array (PTA) can be used to directly detect nHz gravitational waves (GWs) and present my work in the framework of the European Pulsar Timing Array collaboration, which focused on high-precision timing of 42 MSPs, the characterisation of their noise properties and the definition of the PTA's sensitivity as a GW detector. Finally, I will present the results from using the timing data of specific MSPs to place stringent limits on the parameter spaces of alternative theories of gravity in the quasi-stationary strong-field regime of gravity. [Referees: Prof. Dr. Michael Kramer, MPIfR; Prof. Dr. Norbert Langer, Argelander-Institut; Prof. Dr. Klaus Desch, Physikalisches Institut;Prof. Dr. Theo C. M. Bakker, Institut für Evolutionsbiologie und Ökologie]

	Main Colloquium
Dr Xiaoying Pang	ORATED

Shanghai Institute of Technology, NAOC

Young massive star clusters (YMSCs) have been an interesting research targets due to their special observational results, such as significant mass segregation, discovery of the most massive stars, grey extinctions etc. We take the Galactic YMSC, NGC 3603, as an example to investigate the properties of YMSC. Despite of being only an age of only 1 Myr, NGC 3603 is found to mass segregate down to 30 M⊙ , according to the Λ minimum spanning tree technique. The dependence of the velocity dispersion on stellar mass imply that the mass segregation of NGC 3603 might owning to fast dynamical evolution. The segregated massive stars in NGC 3603, one of which is the most massive stars in the Milky Way, disperse the parental molecular gas via radiation and stellar feedbacks. Though the core of NGC 3603 looks almost free of gas, its total to selective extinction ratio is R_F555W=3.75+/- 0.87, higher than the average Galactic value. Furthermore, its extinction curve, E(λ -F555W)/E(F435W-F555W), at ultraviolet wavelengths tends to be greyer than the average Galactic extinction laws from Cardelli et al. and Fitzpatrick. It is closer to the extinction law derived by Calzetti et al. for starburst galaxies, where the 0.2175 μm bump is absent. Both evidence may indicates an anomalous extinction in NGC 3603, which may due to the clumpy dust distribution within the cluster, and the size of dust grains being larger than the average Galactic ISM. Besides the comprehensive multi-band data of NGC 3603, its formation mechanism is still under debate. To tackle this problem, N-body numerical simulation has been an excellent tool to investigate different scenarios: hierarchical or monolithic. In order to aid the comparison between simulations and observations, we develope GalevNB (Galev for N-body simulations), a utility that converts stellar properties: mass, temperature, luminosity and metallicity of N-body simulations into observational spectral energy distribution and multi-filter magnitudes using the GALEV (GAlaxy EVolutionary synthesis models) package.

	Special Colloquium
Dr. Jacques Roland	ORATED

IAP Paris

Abstract: Structure of nuclei of extragalactic radio sources using VLBI data can be done: 1) modeling the ejection of VLBI components assuming a simple precession of the accretion disk, or the presence of a binary supermassive black hole system, 2) using the results of geodetic suveys, particularly the time series RMS and their correlations with the flux variations and the results found previously, 3) making high frequency VLBI observations at frequencies larger or equal to 43 GHz, these obervation can detect the possible radio emission associated with the 2 black holes. If nuclei of extragalactic radio sources contain binary black hole systems of size of about 1 pc, their size will be between 0.1 to 1 mas. I will present the problems to make the link with GAIA observations with a precision better than 0.15 mas. These binary black hole systems lose the energy emitting gravitational waves, I will discuss their life time and how long they are observable by eLISA during their coalescence phase and the frequency of coalescence of these binary systems

	Informal Colloquium
Dr. Miguel A de Avillez	ORATED

Computational Astrophysics Group, Department of Mathematics, University of Evora, Portugal

We have studied the evolution of the interstellar medium and in particular of the Local Bubble (a cavity excavated by 17 SNe in the last 14 Myrs) by means of three-dimensional multi-fluid numerical simulations which model (i) the gas and its ionic structure, (ii) the formation of molecular clouds and massive stars, (iii) how stars evolve and eventually explode, and (iv) isotope yields in these explosions (in particular ^60 Fe). These simulations require knowing the atomic and molecular data, and depend on a recalculation of all atomic and molecular process rates if the electron/proton distribution function deviates from a Maxwell-Boltzmann distribution. In this talk I will discuss these matters and how we can follow the evolution of the Local Bubble by tracing the Civ, Nv, and Ovi ions, and the distribution of the ^60 Fe isotope between its creation in nearby supernovae and its eventual deposition in ferromanganese crusts in the Earth's oceans.

	Main Colloquium
PD Dr Manami Sasaki	ORATED

Eberhard Karls University Tuebingen

The interstellar medium (ISM) is heated and ionized by radiation, stellar winds, and finally, by supernova explosions of massive stars. These processes are often correlated in space and time, generating interstellar bubbles and superbubbles filled with hot thin plasma with sizes of typically 100 - 1000 pc. Bubbles and superbubbles can be studied best in soft X-ray line and continuum emission, since the plasma in their interiors is very hot (10^6 - 10^7 K). I will present recent results of the observational studies of the hot ISM and discuss the physics of the hot plasma.

	Special Colloquium
Dr Shane OSullivan	ORATED

UNAM

Observations of polarised synchrotron emission from radio galaxies, along with the associated Faraday rotation, provides a highly sensitive probe of magneto-ionic material in radio galaxy environments. Here we present the results of our investigation of the environments of two broad classes of radio-loud AGN (radiative-mode & jet-mode) using broadband radio spectropolarimetry from 1 to 10 GHz. Our results show how we can distinguish between the intrinsic magnetic field properties of sources and the external magnetised environment that causes depolarisation, using our polarization model-fitting approach. Overall, we find that the radiative-mode AGN are in more turbulent magnetised environments and have more intrinsically disordered magnetic field structures than the jet-mode AGN, on average. To finish, I will outline some prospects for future Faraday rotation studies from all-sky radio polarisation surveys, such as with the Australian SKA Pathfinder (ASKAP).

	Main Colloquium
Prof. Ralph Pudritz	ORATED

McMaster University

Radiative feedback is thought to play a crucial role in the formation of massive stars and the star clusters in which they form. I will review the physical problems and large body of work that has addressed these basic questions before turning to our own contributions. For massive star formation, we have developed a new hybrid radiative transfer code that operates in a 3D, adaptive mesh code (FLASH) that can, for the first time, follow the heating and momentum transfer by both discrete stellar sources as well as by diffuse radiative background in complex geometries. We simulate the gravitational collapse of massive dense gaseous "cores" of 30 to 200 solar masses. We find several major differences with respect to previous works including radiatively driven bubbles that don't cool and fragment, as well as a suppression of fragmentation of the massive disks into multiple stars. Our results compare favourably to recent observations of massive disks around massive stars. I will also present our new work on radiative feedback simulations of the formation of young clusters in turbulent Giant Molecular Clouds and on how cloud structure affects this process. In particular, we find that the star formation efficiency in such clouds and the masses of star clusters are strongly influenced by how gravitationally bound the cloud are initially - an effect that is more important than radiative feedback. These results are compared with observations.

	Special Colloquium
Prof. Ralph Pudritz	ORATED

McMaster University

Herschel observations have shown that molecular clouds are highly filamentary, and that these are the sites of star and cluster formation. Observations of magnetic fields in star forming regions indicate that magnetic field strengths are comparable to gravitational energy densities, and must play some dynamical role in star formation. The link between the structure of magnetic fields and filaments revealed by Planck and SMA observations of molecular clouds, suggests that magnetic fields are fairly ordered with respect to dense filaments. On larger scales, fields are often perpendicular to the dense, star forming filaments. In this talk, I will focus on our MHD simulations of magnetic structure on the scales of cluster formation, and explore the question of how magnetic field structures and filamentary flows are related and lead to cluster formation. We also explore how radiative feedback from forming clusters acts to alter the geometry of filaments and fields, ultimately shutting off filamentary flow.

	Promotionskolloquium
Silvia Carolina Mora	ORATED

MPIfR

NGC4631 is a nearby edge-on spiral galaxy with a spectacular radio halo, one of the largest observed among edge-on galaxies. This makes the galaxy an ideal target to study the properties of synchrotron halos, the propagation of cosmic rays from the disk into the halo and to investigate the configuration of the magnetic field out of the plane. Radio continuum observations of NGC4631 were performed with the Karl G. Jansky Very Large Array at C-band in the C & D array configurations, and at L-band in the B, C & D array configurations. To recover the large-scale emission the data were combined with single-dish Effelsberg data. In order to determine the best approach to separate the thermal free-free and nonthermal synchrotron components of the total radio emission in the context of edge-one galaxies, we derive the thermal emission of NGC4631 on a pixel-by-pixel basis by using three different methods to account for dust extinction. We analyze the nonthermal synchrotron emission by deriving vertical scale heights, studying its spectral index distribution and by estimating energy losses of cosmic rays. In addition, we present the distribution of polarized emission, Faraday depths, and the intrinsic magnetic field orientation of NGC4631 estimated by employing the RM-synthesis algorithm. [Referees: Prof. Michael Kramer, MPIfR; Prof. Dr. Thomas H. Reiprich, Argelander-Institut für Astronomie, Universität Bonn; Prof. Dr. Jochen Dingfelder, Experimental Particle Physics (Belle/Belle II and ATLAS Experiments) Physikalisches Institut Universität Bonn; Prof. Dr. Barbara Kirchner. Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Universität Bonn]

	Lunch Colloquium
Dr. Kaustuv Basu	ORATED

AIfA

ALMA, the most powerful millimeter/submillimeter telescope ever built, is producing an impressive array of scientific results. Its power comes from an unmatched combination of sensitivity and angular resolution, but how does it see galaxy clusters, the largest gravitationally bound objects in the universe, that can span tens of arcminutes on the sky? I will present some results from the ALMA Early Cycle observations where the Sunyaev-Zel'dovich (SZ) effect was used to image galaxy clusters in the lowest frequency ALMA band (100 GHz). This way, ALMA is probing directly the diffuse baryonic component of galaxy clusters and not its constituent galaxies or lensed background galaxies. In particular, I will show the ALMA detection of a galaxy cluster merger shock at half the current age of the universe, the highest redshift such structure known.

	Promotionskolloquium
Philip Schmidt	ORATED

MPIfR

The nearby edge-on spiral galaxies NGC 891 and NGC 4565 have been studied in terms of cosmic-ray (CR) propagation and magnetic field properties, based on observations in the framework of Continuum HAlos in Nearby Galaxies – an EVLA Survey (CHANG-ES). This full-polarization survey makes use of the novel broad-band technology of the recently upgraded Karl G. Jansky Very Large Array (JVLA) to study a sample of 35 edge-on galaxies at radio frequencies of 1.5 GHz (L-band) and 6 GHz (C-band), at various spatial resolutions. Investigating the spectral index distribution in both galaxies shows that in NGC 4565 the spectral steepening between the two frequencies is significantly stronger than in NGC 891, and in agreement with single-shot CR injection models rather than continuous CR injection. This suggests very low CR injection rates for NGC 4565, consistent with its low SFR and its relatively weak synchrotron emission. While the scale heights of the synchrotron halo are similar for both galaxies, they are found to be identical at 1.5 and 6 GHz for NGC 891, whereas for NGC 4565 a slight frequency dependence is observed. These findings indicate that CR transport is dominated by convection in NGC 891 and at least to a significant degree happening by diffusion in NGC 4565. Modelling the vertical decrease of the synchrotron intensity and of the total magnetic field strength in NGC 891 by solving the vertical diffusion-loss equation confirms a predominantly convective CR transport mode for this galaxy. Convection speeds are likely to exceed 300 km/s, indicating that the CRs are able to escape the gravitational potential of the galaxy as a galactic wind. The modelling furthermore yields magnetic field scale heights significantly lower than the expected equipartition value, which shows that energy equipartition between CRs and magnetic fields breaks down in the halo of NGC 891. Analyzing the broad-band polarization data using rotation-measure (RM) synthesis provides the first unambiguous detection of a non-plane-parallel halo magnetic field in NGC 4565, which is probably X-shaped, like that of NGC 891. At the highest resolution (3''), the total intensity maps of NGC 4565 reveal a ring-shaped structure of the inner spiral arms that was previously only seen in the dust and molecular gas components. Given the high inclination of 86°, these inner spiral arms must be comparatively thin in the vertical and/or coplanar direction. [Referees: Prof. Dr. Michael Kramer, Max-Planck-Institut für Radioastronomie; Prof. Dr. Pavel Kroupa, Helmholtz-Institut für Strahlen- und Kernphysik; Priv.-Doz. Dr. Paul-Dieter Eversheim, Helmholtz-Institut für Strahlen- und Kernphysik; Prof. Dr. Barbara Reichert, Steinmann-Institut für Geologie, Mineralogie und Paläontologie]

	Main Colloquium
Dr Simon Johnston	ORATED

CSIRO Astronomy & Space Science, Australia

I will describe what we know about Fast Radio Bursts with particular emphasis on observations with the Parkes radio telescope in Australia. I will talk about the particular case of FRB150418 recently published in Nature and I'll end with some speculation of how the field might evolve.

	Special Colloquium
Dr Konrad Tristram	ORATED

ESO

The central engine of Active Galactic Nuclei (AGN) is surrounded by dense molecular and dusty material on parsec scales. Typically referred to as the "dusty torus", this material is a key ingredient of AGN because it (1) provides the angle dependent obscuration of the central engine and (2) most likely plays an important role for the accretion of the material onto the supermassive black hole. In the last ten years we have made a large progress in determining the properties of the torus using interferometry in the infrared. These measurements go far beyond AGN demographics and the modelling of spectral energy distributions, because they spatially resolve the thermal emission from AGN heated dust. In my talk I will give a brief overview of the results our interferometric measurements have revealed: In general, the thermal dust emission is parsec-sized, and scales with the luminosity of the central source, albeit with a large scatter suggesting significant differences in the dust distributions between individual objects. Surprisingly, we discovered the dust emission to be elongated rather in the polar direction in several objects, than in the direction of the plane of the torus. I will specifically demonstrate this using the case of the Circinus galaxy, which is one of the sources best studied interferometrically. For this source, I also hope to be able to show a first glimpse at our recently taken ALMA data on which I will be working during my visit in Bonn.

	Lunch Colloquium
Prof. Jim Cordes	ORATED

Cornell University

I will discuss possible answers to the question in the title that involve scattering and scintillations in host galaxies and in the Milky Way. Gravitational microlensing also will be briefly discussed.

	Main Colloquium
Dr Paolo Padovani	ORATED

ESO

IceCube has recently reported the discovery of high-energy neutrinos of astrophysical origin, opening up the PeV (10^15 eV) sky. These observations are challenging to interpret on the astronomical side and have triggered a fruitful collaboration across particle and astro-physics. I will make the case for extreme blazars, i.e. strong, very high energy gamma-ray sources of the high energy peaked type, to be the counterparts of at least some of the IceCube neutrinos. Our results are based on: 1. a joint positional and energetic diagnostic that makes use of high-energy source catalogues; 2. a theoretical modelling of their spectral energy distributions within a lepto-hadronic scenario; 3. a detailed calculation of the neutrino astrophysical background from the whole BL Lac class based on an extrapolation of our findings from individual sources through sophisticated Monte Carlo simulations, which reproduce all the main properties of blazars in the radio, X-ray, and gamma-ray bands. Our first approach gives a positive correlation between extreme blazars and IceCube neutrinos, which is significant at the 0.4% level, with these sources explaining ~ 10 - 20% of the IceCube signal. This scenario should be testable in the next few years by further IceCube data. The talk is self-contained, requires no previous knowledge of neutrinos or blazars, and has been prepared for a very broad audience.

	Special Colloquium
Prof. Henric Krawczynski	ORATED

Washing University in St. Louis

Gravitational lenses have emerged as a powerful tool to study the inner structure of the accretion flows and jets of Active Galactic Nuclei (AGNs). The most exciting results have come from monitoring gravitationally lensed Quasi-Stellar Objects (QSOs) in the optical, UV, and X-ray bands. For a subset of the monitored sources, the observations revealed clear evidence of microlensing of the QSO emission by stars in the lensing galaxy. I will report on a study of the gravitationally lensed quasar RX J1131−1231 for which Chandra observations reveal the presence of one or two Fe K-alpha lines with time variable line amplitudes, line centroids, and line widths (Chartas et al. 2015). The detection of multiple and time variable lines can be explained by the selective magnification of X-rays coming from different regions of the accretion disk with different Doppler and gravitational red and blue shifts of the emergent radiation. I will discuss the potential of using such observations for measuring the black hole inclination and spin and for constraining the geometry of the accretion disk and its corona.

	Lunch Colloquium
Dr. Bindu Rani	ORATED

MPIfR

The high radio frequency polarization imaging of non-thermal emission from AGN is a direct way to probe the magnetic field strength and structure in the immediate vicinity of SMBHs and is crucial in testing the jet-launching scenario. To explore the magnetic field configuration at the base of jets in blazars, I took advantage of the full polarization capabilities of the GMVA. I studied the sub-milliarcsecond structure of the core and central jet of BL Lac. The source is polarized and the EVPA is aligned well with the jet in the North-South direction. This suggests a well-ordered magnetic field, with its main component being perpendicular to the jet axis. Such a field configuration is consistent with a helical magnetic field in the get. I will also compare the source morphology at 7mm/3mm ground VLBI and the 1.3cm RadioAstron imaging results.

	Special Colloquium
Prof Patrice Theulé	ORATED

Aix-Marseille University, France

I will review in this talk how it is possible to form complex organic molecules (COMs) in laboratory, on the surface of interstellar grains analogues or in the mantle of interstellar ice analogues. I will stress on a particular class of reactions: the purely thermal reactions, which happen when warming-up the ice mantle. I will then present how it is possible to measure in laboratory the dynamics of these reactions. Laboratory experiments enable to understand the microphysics on grains and help to improve gas-grain astrochemistry models.

	Special Colloquium
Dr Mario Tafalla	ORATED

Osservatorio Astronomico National, Madrid

Star formation is largely a fragmentation process. A molecular cloud typically contains tens of thousands of solar masses of material, and to form stars, it needs to fragment into parcels about the mass of our Sun. Understanding star formation therefore requires following the process of cloud fragmentation over multiple spatial scales, and identifying the different structures that appear at each of these scales. Dense cores have been recognized for some time as the simplest structures that form stars, and probably represent the last stage in the fragmentation cascade of a molecular cloud. In recent years, filaments have been identified as larger but also characteristic structures of cloud fragmentation. Filaments appear in both inert and star-forming gas, and kinematic studies of their material often show that they have a complex internal structure. In this talk, I will present recent work that attempts to understand the internal structure of star-forming filaments, and their connection with dense cores. For this, we make use of molecular lines, which provide critical information on the gas kinematics and chemical constraints on the core-forming process.

	Main Colloquium
Dr. Else Starkenburg	ORATED

AIP

The lowest metallicity stars that still exist today probably carry the imprint of very few supernova. As such, they represent our best observational approach to understand the First Stars. In this talk I will review the early (chemical) evolution of the Milky Way system from both modeling and observational perspectives. In particular, I will present results of the Pristine survey, a Franco-Canadian photometric survey of the Milky Way halo designed to efficiently decompose the metallicity structures of the Milky Way halo. I will show how we can use this great discriminatory power to hunt for the very rare extremely metal-poor stars (bearers of the chemical imprint of the first stars), to weed out contaminants around metal-poor dwarf galaxies, and to search for stellar structures in the halo.

	Promotionskolloquium
Frédéric Jaron	ORATED

MPIfR

X-ray binaries are composed of a normal star and a compact object which accretes matter from the companion. A subclass of these systems also emits in the gamma-ray regime, the physical processes behind this gamma-ray emission, however, are still under debate. The binary system LS I +61°303 is particularly suitable to study the physical processes behind radio and gamma-ray emission, because the emission from this source is highly periodic, implying that the physical conditions repeat on timescales of about one month. LS I +61°303 is composed of a Be star and a compact object in an eccentric orbit, along which accretion is predicted to peak twice, giving rise to two ejections of relativistic particles along the orbit. Timing analysis of radio data results in two close periods, P1 ~ 26.5 days, which is the orbital period, and P2 ~ 26.9 days, which is compatible with the precession period of a relativistic jet. Knowledge about these intrinsic periodicities allows for a straightforward prediction of radio outbursts, occurring during orbital phases around apastron passages. We used that predictability to schedule radio observations with the 100-m telescope Effelsberg, the resulting light curves reveal the presence of further periodicities at much smaller time scales (hours). Analysis of Fermi-LAT gamma-ray data led to the discovery that the GeV apastron emission presents the same timing characteristics (P1 and P2) as the radio outburst. In contrast to that, the periastron emission is only modulated by P1 and not P2. We present a physical model able to reproduce and explain both the timing characteristics and the relationship between precession (P2) and Doppler boosting of the emission. The model calculates the synchrotron and inverse Compton emission of a relativistic precessing (P2) jet, periodically (P1) refilled with relativistic electrons twice along the orbit. Conclusion of this work is that the GeV emission is mainly the result of upscattering stellar seed photons to GeV energies via the inverse Compton process (external inverse Compton) with additional Doppler boosted emission of the upscattered jet photons (synchrotron self Compton) when the jet is almost aligned with the line of sight. In this context we discuss how all gamma-ray emitting X-ray binaries have indeed a high-mass companion and in addition present our radio results for the Be-BH binary MWC 656. [Priv.-Doz. Dr. Maria Massi, MPIfR; Prof. Dr. Norbert Langer, Argelander-Institut; Prof. Dr.Dr. Ian Brock, Physikalisches Institut; Prof. Dr. Hubert Schorle, Institut für Pathologie]

	Master Colloquium
Leon Houben	ORATED

MPIfR

Since the discovery of a new type of radio transient called fast radio bursts, no detection has been able to unambiguously pinpoint the sky position of their source. These bright, millisecond-duration radio pulses show large dispersion measures that are most easily explained by an extragalactic origin. Fast radio bursts, therefore, might present a method to probe the intergalactic medium and test cosmology if the positions and distances of their sources are known. Much effort is undertaken to develop new detection methods that can determine the exact location of an occurring fast radio burst, but their supposed non-repeating nature makes this determination difficult. In this thesis we present a pipeline currently under development at the Max Planck Institute for Radio Astronomy and the Radboud University that enables the simultaneous detection of a radio transient with the Effelsberg 100 m single dish radio telescope and ASTRON’s Low Frequency Array (Lofar). The main contribution of this thesis was to implement the communication framework that sends triggers from Effelsberg to Lofar, allowing the observatories to detect the same signal. This is possible since a burst with a DM typical for FRBs has a delay of up to a few minutes to arrive at Lofar’s observing frequency from the top of the Effelsberg band. If a radio transient like an FRB is so detected, it is possible to pinpoint its exact location by imaging Lofar’s interferometric data and possibly discover its host galaxy. Simultaneous Effelsberg and Lofar test observations on pulsars showed that the basic concept of the pipeline works, but that it has to be improved to resolve some minor shortcomings prior to regular use. Analysis of this data revealed pulse-to-pulse variations as well as frequency-dependent variations between the observatories bands, which could tell us more about single pulse properties of pulsars. Thus, the pipeline would not only contribute to the detection of new radio transient phenomena but also lead to a better understanding of known sources.

	Main Colloquium
Dr Stefan Oslowski	CANCELED

Bielefeld University

Some of the quickly-spinning, highly-magnetized neutron stars emit radio waves in two beams originating in their magnetic poles. Because of the misalignment of the dipolar magnetic field poles with the angular momentum vector, these beams sweep through our Galaxy. If one such beam passes through the Earth we may detect a burst of polarised radio emission. Thanks to the polarization and pulsed nature of the signal we can use these stars to probe the cold free electron plasma in the interstellar medium as we can detect its effects on the propagating emission from the neutron star. In this talk I will present some recent results related to such phenomena based on observations undertaken with facilities available in Germany such as the Effelsberg Radio Telescope as well as the international LOFAR stations.

	Promotionskolloquium
Jana Köhler	ORATED

MPIfR

The Low Frequency Array (LOFAR) is an international telescope operating at frequencies from 10 to 240 MHz. The use of a single international station with a diameter of around 60 m allows to study large scale structures in the universe. Even more, with its wide frequency range and the ability to observe in polarization, LOFAR allows polarization studies at frequencies below 240~MHz. In this talk I will present a new northern sky survey at radio frequencies below 200 MHz, observed with the LOFAR station located in Effelsberg. Using data of a single station of this array a novel approach has developed to produce this survey. The necessary steps are described on how to generate a scientific usable sky map from the raw voltages. Especially the self-calibration will become an important method, to calibrate strong unknown structures and individual sources, to improve the image quality. Some of the strong unknown source can be an active Sun, a bursting Jupiter or even just strong men made radio frequency interference (RFI). Afterwards an analysis of the spectral index maps between frequencies below 50 MHz and the high frequency surveys at 408 MHz (Haslam et al., 1982), 820 MHz (Berkhuijsen, 1972) and 1400 MHz (Reich et al., 1981) will be investigated. This allows to study physical nature of the continuum emission and a possible flattening of the spectrum toward lower frequencies due to thermal absorption. At the end of my talk the polarization properties of Jupiter bursts observed with a single LOFAR station will be discussed. The measurements show that the bursts are highly linear- and circular-polarized and that the rotation measure (RM) values per burst are frequency depended.

	Special Colloquium
Dr Paul F. Goldsmith	ORATED

Jet Propulsion Laboratory, California Institute of Technology

Atomic and ionic fine structure lines are potentially powerful probes of conditions in multiple phases of the interstellar medium. With the advent of space observatories, astronomers have been able to measure their emission from a range of galaxies, and Herschel enabled large-scale surveys of the Milky Way and imaging of nearby galaxies. Models for fine structure line (FS) line emission are thus being tested, and new uses of these lines are being developed. In this talk, I focus on recent Herschel surveys of the Milky Way in the [CII] 158 μm line and [NII] 122 and 205 μm lines. Carbon is ionized in a wide range of conditions and thus its emission is widespread, but determining the actual source of the emission is a challenge. In the GOT C+ survey, we used comparisons with HI and CO surveys to determine that a significant fraction of the 158 μm line emission arises from gas in which hydrogen is molecular but carbon is ionized rather than being in molecular form. This “CO Dark Molecular Gas” adds approximately 30% to the molecular mass of the Milky Way, and is particularly prevalent in the outer portions of our galaxy. A second survey of [NII] emission, which arises from ionized gas, used its two FS transitions to determine a mean electron density of ~30 cm-3 in this gas that seems widespread in the inner portion of the Milky Way. Other topics that I will cover include the use of and problems with FS lines as tracers of star formation, and the contribution that upcoming balloon, aircraft and space missions should make to our understanding of the evolution of the ISM and star formation.

	Main Colloquium
Prof. Dr. Rony Keppens	ORATED

KU Leuven

The dust­producing Wolf­Rayet 98a binary system is one of a few known rotating pinwheel nebulae, when probed at infrared wavebands. We present the first comprehensive 3D hydrodynamic model for WR98a, where dust creation and redistribution are self­consistently incorporated. With grid­adaptive gas­dust simulations [using our open source MPI­AMRVAC simulation toolkit: Keppens et al., 2012, JCP 231, 718; Porth et al., 2014, ApJS 214, 4], we resolve details in the wind collision region (WCR) between the WC9 and OB star at scales below one percent of the orbital separation (about 4 AU), while simulating a region extending up to 1300 AU. We cover several orbital periods in models where either adiabatic, or radiatively cooling conditions prevail. In the adiabatic case, mixing between both stellar winds is most effective in a well­defined spiral pattern, where optimal conditions for dust creation are met. We parametrize the (subgrid) details of dust formation, but model the resulting drag­force mediated redistribution in detail. When radiative cooling is incorporated, the wind interaction gets dominated by thermal instabilities along the WCR, and dust concentrates in clumps and filaments, in a more spherical, volume­filling fashion. With a Monte Carlo radiative transfer code, we obtain synthetic infrared views, which mimic Keck, ALMA, or E­ELT sensitivities. We then investigate the effects of resolution, orientation and variability in virtual infrared images, for cases with and without cooling. The large­scale, long­term aspect of our model also allows for virtual photometric observations. These confirm the observationally inferred variability and orientation of the WR98a system, which must obey close to adiabatic evolutions to demonstrate the rotating pinwheel structure, with the observed flux variation.

	Lunch Colloquium
PD Dr. Silke Britzen	ORATED

MPIfR

Despite numerous and detailed studies of the jets of Active Galactic Nuclei (AGN) on pc-scales, the phenomenon remains intriguing and many questions are still debated. The physical nature of the jet-components is one of the most prominent unsolved problems as is the launching mechanism of jets in AGN. Another long-standing question is whether the central massive objects in AGN are instead close pairs of supermassive black holes (SMBHs). Gravitational waves from binary SMBHs should be detectable by pulsar timing arrays. I will present examples of how we identify potential close binary black hole candidates based on in-depth investigations of long-term archival VLBI and multi-wavelength data (several decades) in combination with the application of theoretical models. This enables us to discriminate between motion scenarios and to derive a more physical understanding of the nature and and origin of jets in general.

	Main Colloquium
Dr Joe Hennawi	ORATED

MPIA

There is no such thing as empty space. Indeed, the most barren regions of the universe are the vast expanses between the galaxies, known as the intergalactic medium (IGM). Averaging just one lonely atom per cubic meter, this primordial gas left over from the Big Bang encodes fundamental information about our universe’s history. About half a million years after the Big Bang, the plasma of primordial baryons recombined to form the first neutral atoms, releasing the cosmic microwave background and initiating the cosmic 'dark ages'. During this period primordial gas expanded and cooled to very low temperatures T~20 K, until the stars and black holes in the first galaxies emitted enough ionizing photons to reionize and reheat the universe. The thermal state of gas in the IGM is a relic of this reionization phase transition, which can be measured via optical observations of bright distant quasars at cosmological lookback times of a few gigayears. On Mpc length scales, gas in the intergalactic medium traces density fluctuations in the underlying and gravitationally dominant dark matter, but on smaller scales of one hundred kpc, fluctuations are suppressed because the ~10^4 Kelvin gas is pressure supported against gravity, analogous to the classical Jeans argument. This Jeans pressure smoothing scale thus quantifies the small scale structure of the IGM and provides a record of cosmic reionization and thermal evolution. Recently we have shown that it is possible to directly measure this scale by characterizing the coherence of correlated intergalactic absorption lines in the spectra of pairs of quasars with small angular separation on the sky. I will describe a statistical method which quantifies correlated absorption in quasar pair spectra that is highly sensitive to the pressure smoothing scale, and present its first-ever measurement with data collected from 8m telescopes. Our results suggest that the pressure smoothing scale is smaller than expected from standard models of reionization and the thermal evolution of the IGM.

	Special Colloquium
Dr. Nissim Kanekar	CANCELED

National Centre for Radio Astrophysics, India

Damped Lyman-alpha Absorbers (DLAs) are the high-redshift counterparts of today's normal gas-rich galaxies, with high HI column densities, N_HI >= 2e20 per cm^2. Despite their acknowledged importance in the context of galaxy evolution and thirty years of research, the nature of high-redshift DLAs remains an open issue. I will describe results from a slew of studies over the last decade, probing the gas temperature of DLAs, their HI mass, their molecular gas mass and their star formation rate. Finally, I will attempt to relate the host galaxies of DLAs to emission-selected high-z galaxy populations, such as the Lyman-break galaxies and the Lyman-alpha emitters.

	Lunch Colloquium
Dr. Michael Bird	ORATED

AIfA

The Radio Science Experiment (REX) on the New Horizons mission measured key characteristics of Pluto and Charon during the brief encounter on 14 July 2015. The REX flight hardware, integrated into the spacecraft’s X-band radio transceiver, provides high precision, narrow band recording of powerful uplink transmissions from Earth- based stations, as well as measurements of broadband radiometric power. This talk is a brief overview of the performance and initial results of the radio occultations and radiometric temperature profiles of Pluto and Charon. While the New Horizons spacecraft was flying behind the limbs of Pluto and Charon, the REX instrument recorded four 20-kW uplink signals that were transmitted from the NASA Deep Space Network in two polarizations at 4.2 cm wavelength. The tiny phase shifts of the uplinks during occultation ingress and egress provide a precise measure of the density structure of the lower atmosphere, including height profiles of pressure and temperature down to the surface. In addition, shortly after the closest approach, REX measured the thermal radio emission from Pluto at 4.2 cm during two limb-to-limb scans across the disk. Radiometric observations of Pluto and Charon were also obtained on the night side during the interval between occultation ingress and egress.

	Main Colloquium
Prof. Laurent Loinard	ORATED

Using Very Long Baseline Interferometry (VLBI), it is possible to measure the distance and the velocity vector of young stars located within 500 pc of the Sun with an accuracy of order 1%. In this talk, I will present the first results of a large project called "The Gould's Belt Distances Survey" that takes advantage of this possibility to measure the mean distance, and the internal structure and kinematics of the most prominent star-forming regions associated with Gould's Belt: Ophiuchus, Taurus, Serpens, and Orion. I will discuss the implications of these measurements both for star-formation and for Galactic structure studies.

	Lunch Colloquium
Dr. Dario Colombo	ORATED

MPIfR

Giant Molecular Clouds (GMCs) represent one the preferred ways in which the molecular gas organizes itself and are consider as the places where stars are born. These objects, therefore, play a key role in controlling star formation and defining its modes. However, the relationships between their physical properties and environment are still poorly understood - especially in spiral galaxies. The development of powerful interferometers, as NOEMA and ALMA, opened up the era of the high resolution, wide-area mapping of the molecular ISM in galaxies outside the Local Group, able to fill this gap. In particular, the pioneer PdBI Arcsecond Whirlpool Survey of the inner part of M51 has demonstrated that large-scale dynamics have profound impact in the formation and evolution of GMCs, and in their capability to form stars. Guided by these results, in this talk I will show new GMC decompositions of ALMA observations as NGC628, NGC1068, and M100. Together, I will discuss how dendrograms can be useful tools to study the environments where GMC form and evolve, and to compare between galaxy observations of different resolution and sensitivity.

	Main Colloquium
Prof Elias Brinks	ORATED

Center for Astrophysics Research, University of Hertfordshire

LITTLE THINGS is a deep, high resolution VLA HI survey of 40 nearby dwarf irregular galaxies. The survey is supported by a host of ancillary data, ranging from the FUV (GALEX) through optical/IR to the Far-IR (Spitzer and Herschel). It has spawned a parallel VLA survey to map the same sample at radio continuum (6 GHz) and, for a few targets, millimetre wavelengths with APEX and ALMA. The motivation for undertaking this massive project is to gain a better understanding of the star formation process, by probing star formation in the low mass, low metallicity regime, thus extending the work done in “normal” spiral galaxies based on the THINGS (The HI Nearby Galaxy Survey). I will present our analysis of the Schmidt-Kennicutt behaviour in our sample and compare it with that found in spirals, will present deep radio continuum resolved imaging (rms ~ 6muJy) of our targets, and argue to what extent the radio data can be used as an alternative star formation rate indicator (i.e., follow the Condon and radio-continuum - Far IR relations). Lastly, I will report on our success in breaking the low metallicity barrier, revealing dozens of tiny CO clumps in our ALMA maps of the nearby dIrr WLM which has a metallicity corresponding to only 13% solar.

	Special Colloquium
Dr. Bill Cotton	ORATED

NRAO

The ARCADE-2 CMB balloon experiment detected an unexplained low frequency component which was postulated to be a previously unknown population of extragalactic sources. We conducted a deep 2-4 GHz survey with the recently upgraded EVLA to search for this population and to measure the faint radio source counts. Faint source counts constrain the cosmic evolution of the populations represented including sources powered by star formation. Previous attempts at measuring faint source counts produced more scatter in results than are easily accounted for and may reflect the variety of techniques used to correct for various effects. I will describe a deep confusion limited analysis using the "P of D" technique to derive the source counts at, and below the confusion which avoids many of the difficult to correct effects. Results are in excellent agreement with theoretical expectations effectively ruling out the ARCADE-2 anomaly being due to discrete sources. I will also summarize ongoing observations to determine the size distribution of the microJy population.

	Lunch Colloquium
Dr. Laura Spitler	ORATED

MPIfR

Fast radio bursts (FRBs) are a population of broadband, short-duration, isolated radio bursts that originate from extragalactic sources. The exact astrophysical origin of these bursts is still unknown, but recent observations of a repeating FRB, the first of its kind, have eliminated a large number of models. FRB 121102, discovered by the Pulsar ALFA survey with the Arecibo Observatory, was redetected first in follow-up observation with Arecibo and then later with the Green Bank Telescope. I will present these new bursts, as well as follow-up with the Jansky VLA, Chandra, and Swift.

	Special Colloquium
Dr Phillip Galli	ORATED

Observatoire de Grenoble (France) and U. Sao Paulo (Brazil)

A precise determination of the distance to individual stars is required to reliably determine the fundamental parameters of young stellar objects. While the average distance to nearby star-forming regions is often known, the distances to individual stars are usually unknown. Individual distances for members of young moving groups can be derived from their proper motions, radial velocities and the convergent point of the moving group. In this talk I will present a new version of the convergent point method and its application to nearby star-forming regions and young stellar associations to calculate individual distances of cluster members. The newly derived distances are used in this work to investigate the cluster kinematics and to refine the physical properties of young stars (mass, age and the lifetime of circumstellar disks).

	Main Colloquium
Prof. Clive Dickinson	ORATED

Jodrell Bank Centre for Astrophysics

In this talk I will give a summary of my work, which is focussed on diffuse radio foregrounds. Foregrounds, such as synchrotron and free-free radiation, hinder cosmological analyses (e.g. for the CMB). They are also of astrophysical interest themselves. For example, CMB data have revealed a new component of diffuse Galactic radiation, often referred to as “anomalous microwave emission” (AME). AME is thought to be due to electric dipole radiation from spinning dust grains, but there is still significant debate. I will cover a number of areas, from low frequency radio surveys including C-BASS, CMB analysis including new Planck data, and radio recombination line (RRL) surveys. I will discuss how they aid CMB component separation, as well as revealing new information about our Galaxy.

	Lunch Colloquium
Dr. Eleni Vardoulaki	ORATED

AIfA

Luminous infrared galaxies in the local Universe, due to their dusty nature, are excellent laboratories to study dust properties of galaxies and investigate the possible dust heating mechanisms, attributed either to an active galactic nucleus (AGN) or a starburst (SB). We use Spitzer and Herschel data to create dust temperature maps for a sample of LIRGs from the GOALS sample at low redshift (z < 0.088), which appear to be most extended at radio VLA 1.49 GHz observations (6 arcsec resolution). The purpose is to explore the connection of radio emission to star formation and dust heating mechanisms. We use PACS and Spitzer photometry to investigate cold and warm dust, and get a census of the warm/cold dust distribution and of the extend of the obscured nuclear regions in these LIRGs. With the aid of spatially resolved q maps (q = log(f_IR / S_radio), q8um & q24um) we point to the location of regions of intense synchrotron emission due to a SB or an AGN. By comparing dust temperature variations to variations in the IR/radio correlation, given by the q maps, we explore the AGN/SB connection in these LIRGs spatially. Finally, we compare the spatially resolved IR/radio correlation to radio spectral index maps for these sources in order to understand the physics behind the variations in q.

	Lunch Colloquium
Dr. Ioannis Myserlis	ORATED

MPI für Radioastronomie

We present a framework for the study of the physical conditions in astrophysical plasma elements through linear and circular polarization monitoring. This framework can be used to (i) estimate the four Stokes parameters of the observed radiation with high accuracy, (ii) interpret polarimetric observations based on the theoretical predictions of synchrotron emission and propagation through magnetized astrophysical plasmas as well as (iii) reproduce the observed polarization characteristics and their dynamics using a polarized radiative transfer code. Here we present the application of this framework on radio and optical monitoring datasets of AGN jets. We present the linear and circular polarization properties of 87 AGNs measured by the F-GAMMA program. The dataset spans from 2010 to 2015 and includes 4 radio frequencies between 2.6 and 10.5 GHz with a cadence of 1.3 months. We use their polarization characteristics to extract information for the physical parameters and the variability processes in the jet regions where the radiation is emitted and propagated through, e.g. the magnetic field properties or the plasma composition. Furthermore, we implement a realization of the polarized radiative transfer code that attributes the variability to evolving internal shocks, to investigate the conditions and processes needed to reproduce the observed polarization behavior. This model was successfully applied for the blazar 3C 454.3. Finally, we analyze R-band linear polarization light curves for 49 sources monitored with the RoboPol program since 2013 with a cadence of a few nights. Here we present population studies based on the radio polarization data, the results of the model application for 3C 454.3 and of the correlation analysis between the radio and optical linear polarization properties.

	Special Colloquium
Dr. Luca Moscadelli	ORATED

Astrophysical Observatory of Arcetri (Florence)

As predicted by models, well constrained by observations, low-mass (M_star ~ M_sun) stars form by increasing mass via an accretion disk and removing the angular momentum excess in a fast jet collimated along the disk axis. The process of formation of high-mass (M_star > 10 M_sun) stars is complicated by the presence of the ultraviolet radiation of the massive (proto)star, which, ionizing and exerting pressure on the circumstellar environment, can significantly alter the formation path compared with the "standard" disk/jet scenario. Since massive stars form in tight clusters at typical distances of several kpc, previous observations have suffered from insufficient angular resolution (>0.5-1") , which prevented resolving and studying the gas kinematics around individual high-mass (proto)stars. This talk report on recent ALMA (thermal continuum and molecular line) and multi-epoch VLBI (maser) observations of G24.78+0.08, one of the best studied high-mass star forming regions. Combining the ALMA data (angular resolution ~ 0.15") with the maser information (on milliarcsecond scale) allows us to separate individual objects and constrain the 3-D kinematics of the gas around them.

	Lunch Colloquium
Dr. Mark Reid	ORATED

Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, U.S.A.

The BeSSeL Survey is providing parallax measurement for high-mass star forming regions, which give a sparsely sampled map of the Galaxy's spiral structure. We have developed a Bayesian approach to leverage these results to estimate distances to large numbers of sources from surveys based only on Galactic coordinates and velocities. Using this program we have made perhaps the most realistic visualization of the Milky Way's spiral structure. Another interesting result from BeSSeL parallaxes are that spiral arms expand with increasing radius from the Galactic center. We investigated if this happens in other galaxies and found some interesting properties of spirals.

	Special Colloquium
Prof. Naomi Ota	CANCELED

Nara Womens University, Japan

TBD

	Lunch Colloquium
Andreas Horneffer	ORATED

MPIfR Bonn / Radboud University Nijmegen

When working with LOFAR data to make total power images one faces two particular problems: large amounts of data and the need for direction dependent calibration. The raw data for a typical LOFAR observation is about 20 TByte. We wrote a pipeline that combines the usual pre-processing and initial, direction-independent calibration, and that can efficiently run on a compute cluster with little human supervision. During this pre-processing the data is usually compressed to about 500 GByte and a few dozens of files. When imaged the resulting images from this calibration still show artifacts from the lack of direction dependent calibration, but if not the very best image quality is needed then they can already be used for science. The Earth's ionosphere changes on time-scales of seconds and within the LOFAR beam. To correct for this we do direction-dependent calibration as facet calibration: the full field-of-view is split into facets and each facet is calibrated independently. We are currently working on a program that allows a non-expert astronomer to run the facet calibration with minimal human supervision. There are still problems when processing complicated fields, but on well behaved fields the program can already now be used successfully.

	Special Colloquium
Prof. Dr. Andreas Burkert	ORATED

Ludwig-Maximilians University Munich

The Galactic center is one of the most fascinating and extreme places in the Galaxy. Harboring a supermassive black hole with a mass of order 4 million solar masses it experiences cycles of activity and star formation, separated by periods of quiescence that last of order a million years. The Milky Way's SMBH currently is inactive. However a small, diffuse gas cloud (G2) has recently been detected (Gillessen+ 2012, 2013, 2014, Pfuhl + 2015) on an orbit almost straight into the Galactic SMBH. In 2014 G2 started to pass the SMBH at a small distance of just 2000 Schwarzschild radii, corresponding to 20 light hours with the emission changing from being strongly redshifted prior to pericenterto strongly blue-shifted past pericenter. This indicates that the ionized gas of G2 is now stretched over more than 15,000 Schwarzschild radii around the pericenter. Depending on its nature G2 will now begin to break up and feed the SMBH, possibly triggering a phase of AGN activity. The next years will therefore provide a unique opportunity to investigate directly the processes that drive and regulate gas accretion onto the Galactic SMBH. In addition, G2 turns out to be a powerful probe in order to probe the structure and composition of the Galactic center. This talk will summarize the observations of G2 and current models about its nature. Is G2 a diffuse gas clump that originates from winds of high-mass stars in the surrounding stellar disk, is it a disrupting gas planet or is it the atmosphere of an evaporating, invisible protostellar disk, surrounding a young low-mass stars. Is it connected to a long gas filament that has been discovered recently and that might feed and activate the SMBH in the future? Or is it something completely different? The existence of such a tiny, cold gas cloud in the hostile vicinity of the SMBH raises numerous fascinating questions related to its structure. Where did it come from and where will it go? Why is it on such a highly eccentric orbit? Which physical processes constrain its properties like its size, mass, density, temperature and geometrical shape? Like comet Shoemaker Levy's 1994 collision with Jupiter, the big challenge has started for astrophysicists to predict the outcome of G2's close encounter with the SMBH in the years 2015 and beyond. Their models will be validated directly by observations within the next couple of years.

	Main Colloquium
Prof. Tal Alexander	ORATED

Department of Particle Physics and Astrophysics, Weizmann Institute of Science

I discuss the role stellar dynamical relaxation mechanisms, and in particular rapid but fragile resonant relaxation, plays in various modes of activity displayed by massive black holes (MBHs), and in their formation and evolution. I describe recent breakthroughs in the understanding of relaxation in the relativistic regime, and apply them to predict the rates of direct plunges and gravitational wave emission from inspiralling compact objects, and to model stars around the MBH of the Milky Way. I show how stellar relaxation can play an important role in the behavior of circum-nuclear accretion disks, and apply it to explain the radio observations of the maser disk in NGC4258. Finally, I discuss how rapid relaxation may play a critical role in allowing seed MBHs to grow supra-exponentially fast in the very early universe.

	Promotionskolloquium
Patrick Lazarus	ORATED

MPIfR

Pulsars are the rapidly-rotating, highly-magnetized, neutron star remnants of the supernova explosions of massive stars. I will describe how pulsars are found and how they are used in a wide variety of studies of astronomy and physics. In particular, I will focus on the PALFA survey, a search for radio pulsars using the Arecibo Observatory which has found 163 pulsars to date, follow-up analysis of PSR~J1952+2630, a 20.7-ms pulsar in a binary system with a massive white dwarf companion found in the PALFA survey, the improvement in high-precision timing with the Effelsberg 100-m radio telescope afforded by its new PSRIX data recorder, as well as how studies of the Solar System with pulsars can be used to characterize the International Pulsar Timing Array data set, the largest, most sensitive pulsar timing data set ever assembled.

	Lunch Colloquium
Behnam Javanmardi	ORATED

AIfA

Based on the cosmological principle, the expansion of the Universe and its acceleration should be statistically equal in all directions. In this talk, I present a method to test the isotropy of the magnitude-redshift relation of Type Ia Supernovae (SNe Ia) and single out the most discrepant direction with respect to the all-sky data. To show its potential, we applied our method to the high-redshift SNe Ia from the Union2.1 compilation. We found that though the deviation from isotropy is not significant based on pure signal-to-noise arguments, the most discrepant direction is unexpectedly aligned with the CMB dipole with the 95%-99% confidence level. If this result is not due to a statistical fluke, it might either indicate that the SN data have not been cleaned from all possible systematics or even point towards new physics. (Reference: arXiv:1507.07560)

	Main Colloquium
Dr. Rene Breton	ORATED

University of Southampton

The number of known pulsar binaries belonging to the black widow and redback subclasses has skyrocketed over the last decade. These ‘spiders’ now offer a number of new opportunities to measure neutron star masses and study binary evolution not only in the context of individual systems but also as a population of neutron stars. In this talk, I will discuss some of the recent results that were obtained from the optical follow-up of several of these systems. In particular, I will present some new constraints on the mass of some of these pulsars, the discovery of secular flux changes in a redback system and the study of cataclysmic variable black-widow analogue.

	Special Colloquium
Dr Ronald Laesker	ORATED

University of Turku

In this talk, I will present revised scaling relations of masses (MBH) of Supermassive Black Holes (BHs) with galaxy and bulge properties, focusing on bulge masses (Mbul) in low-mass and late-type galaxies where the bulge is only a minor component. By means of HST/WFC3 optical and near-infrared data, we analyzed BH host galaxies with MBH precisely known by their nuclear Megamaser emission. Due to the superior image quality and detailed analysis techniques, we are able to decompose these complex systems, to isolate and parametrize their likely classical bulges apart from pseudobulge and other disk-like components. Thus we are able to test whether BH (AGN) feedback is effective in and primarily associated with (classical) bulges, irrespective of BH host morphology at large. However, we do not find a particularly tight relation between these systems’ MBH and Mbul, questioning the universal distinguished role of (classical) bulges in a putative co-evolution with their BHs. We also note an apparent offset to lower MBH on average, when compared to the MBH - Mbul relation of early-type systems. Finally, the log-slope of the augmented MBH - Mbul relation is smaller than unity, in contrast to predictions of standard feedback scenarios. Our results demonstrate how nuclear Megamasers are able to significantly improve the characterization of BH scaling relations in this otherwise hard-to-access and undersampled regime of low masses and late host morphologies, and highlight our need for a more detailed and comprehensive theory of the formation and growth of BHs.

	Lunch Colloquium
Dr. Gabriele Bruni	ORATED

MPIfR

Since its launch in 2011, RadioAstron has been collecting data supported by a global ground array. The three AGN imaging projects based at MPIfR are now starting to produce interesting results, taking advantage of the record angular resolution achievable with space baselines. New details about magnetic fields structure in jets, as well as extreme brightness temperature have been found, questioning our current understanding of how the emission is generated in AGN. I will review these results, and give an update on the mission and the next observing opportunities.

	Physics Colloquium
Dr. Bruce Allen	ORATED

AEI, Hannover

This talk follows the annoucement made on February 11th by the LIGO Scientific Collaboration. On September 14, 2015, we detected the gravitational waves emitted by the final few orbits and merger of two black holes. In this talk, I present the main results, as well as some of the "behind the scenes" details of the discovery and subsequent analysis. Reference: B. P. Abbott et al., Phys. Rev. Lett. 116, 061102, 2016.

	Master Colloquium
Celine Chidiac	ORATED

MPIfR

Detailed investigation of broadband flux variability in the blazar 3C 273 allows us to probe the location and size of emission regions, and their physical conditions. The results of the correlation studies of the flaring activity in 3C 273 observed for a period between 2008 and 2012 are presented. The PSD analysis showed that the optical/IR light curve slopes are consistent with the slope of white noise processes, while the slopes at radio, X-ray and γ-ray energies are consistent with the slope of a red noise process. The variability behaviour is complex, where the fractional variability depends on the frequency observed. A significant correlation between the flux variations at γ rays and mm-radio bands has been found. Using the observed time lag of (110±27) days between γ-ray and radio light curves where the γ rays are leading the emission at radio bands, the location of the γ-ray emission region is constrained at a de-projected distance of (1.2 ± 0.9) pc from the jet apex. Flux variations at X-ray bands were found to have a significant correlation with variations at both radio and γ-rays energies. The correlation between X-ray and γ-ray light curves provides a hint of two possible time lags, which suggests two components for the X-ray emission. One X-rayscomponent is emitted closer to the jet apex from a compact region (0.02-0.05 pc in size), most likely from the corona at a distance of (0.5±0.4) pc from the jet apex. and the second component has a jet-based origin at ∼ 4-5 pc from the black hole. The flux variations at radio frequencies were found to be well correlated with each other such that the variations at higher frequencies are leading the lower frequencies, which can be explained in the frame of the shock-in-jet model.

	Special Colloquium
Dr. Karl Schuster	ORATED

Director, Institute de Radioastronomie Millimétrique, Grenoble

Both the 30m telescope and NOEMA currently undergo rapid changes in their capabilities. The current status of the observatories will be presented including an outline of the adopted science strategy and related instrumental development programs.

	Main Colloquium
Dr. David Kaplan	ORATED

University of Wisconsin Milwaukee

Explorations of the radio sky in the time-domain are an exciting frontier in astrophysics, and one where new observational capabilities will open up new windows on the universe. As one of a new generation of widefield, low-frequency radio telescopes, the Murchison Widefield Array has enormous potential to conduct blind searches for radio transients. We are working to develop capabilities for the MWA that will continue to serve the Australian Square Kilometer Array Pathfinder (ASKAP) Variables and Slow Transients (VAST), eventually allowing real-time transient detection and characterization. I will discuss the expected types of sources that we hope to discover with the full array, explore some of our initial results, and highlight plans for the next generation of facilities.

	Special Colloquium
Mélanie Chevance	ORATED

CEA Orsay

I will present a far-infrared (FIR) view of the extreme star-forming region 30 Doradus in the Large Magellanic Cloud (LMC). The 30 Doradus region offers the best laboratory to examine the interplay between stellar activity and a metal-poor interstellar medium (ISM). The main stellar source of radiation is provided by the closest example of a super star cluster, R136, while the ISM is half-solar metallicity. The proximity of 30Dor (50kpc) makes it possible to study gas and dust over large scales in this dramatic environment. The new Herschel/PACS and SPIRE/FTS observation of far infrared (FIR) fine structure lines, combined with Spitzer/IRS spectroscopic maps, are used to constrain the physical conditions in the photo-dissociation regions (PDR) with the Meudon PDR code (Le Petit et al., 2006). This allows us to construct a comprehensive, self-consistent picture of the density, radiation field, and ISM structure. We quantify the effect of intense radiation field on this low metallicity ISM. In particular, we bring constraints to the fraction of molecular dark gas not traced by CO, the so-called “CO-dark gas”. Our follow-up observations with ALMA will reveal the CO and [CI] structures at 0.1pc scales. This spatially resolved study of the star formation activity and the PDR/molecular gas aims at identifying and calibrating the specific diagnostic tracers such as [CII], [CI] and CO that can be used to characterize unresolved high redshift galaxies.

	Special Colloquium
Dr. Bruce Allen	CANCELED

AEI, Hannover

TBD

	Special Colloquium
Dr. Colin Lonsdale	ORATED

MIT/Haystack Observatory

The research enterprise at Haystack spans a wide range of science and technology topics. These include radio astronomy from HF frequencies to sub-millimeter wavelengths, employing angular resolutions from degrees to tens of microarcseconds. Various studies target atmospheric science, comprehensive studies of the geospace environment, the genesis of space weather, and nonthermal solar emissions. Geodetic VLBI and GPS techniques are used in an operational setting, as well as to support scientific investigations into cryosphere dynamics and earth deformation phenomena. The Observatory develops advanced radio array architectures both for passive receive and active radar applications, including high speed voltage recording and data processing systems for VLBI and other applications, systems for radio sensing on small satellite platforms, and a rapidly developing astro and geo informatics program concentrating on machine-aided discovery techniques. Haystack also hosts major research instruments including a 37-meter telescope with ~70 micron rms surface accuracy, and a multi-megawatt class incoherent scatter radar facility. An overview of the Haystack operation and future plans will be presented in the context of evolving technological and scientific landscapes, and associated collaborative opportunities.

	Special Colloquium
Dr Paola Pinilla	ORATED

Leiden Observatory

Transition disks are protoplanetary disks with inner dust cavities and they may reveal an intermediate step of the ongoing disk dispersal process, where planet formation might happen. The recent gas and dust observations of transition disks have given major support to the idea that clearing by planet(s) is the primary cause for the origin of the cavities in transition disks. In this talk I will present gas and dust evolution models of transition disks, and I will show the different structures that disks can have (rings, vortices, spiral arms) when a planet or multiple planets are embedded in the disk. Moreover, I will connect these results with recent SPHERE/VLT and ALMA observations of some of these disks, e.g. J160421, HD 100546, SR 21, and HD 135344B.

	Lunch Colloquium
Iannis Liodakis	ORATED

University of Crete, Greece (student visitor at the MPIfR)

Blazars are some of the most active and mysterious of galaxies with their intrinsic properties shrouded by relativistic effects due to the alignment of their jet to our line of sight. We parametrize the variability using a novel method that treats every outbursting event individually. The method provides accurate estimates of the variability parameters and allows different mechanisms to be operating in the same source and even observing frequency. From this we compute variability Doppler factor (i.e. the amount of the relativistic boosting) using the multi-wavelength radio light curves of the F-GAMMA program. We have constructed a realistic AGN population model which is used to produce all the relevant observables that are subsequently compared to the observed parameters. We will show that the multi-wavelength variability Doppler factors can adequately describe the blazar populations and are the most accurate method yet. We will then use these estimates to clear the fog or the relativistic effects and look straight in the heart of their central engines.

	Special Colloquium
Eric Koch	ORATED

University of Alberta

Star formation is governed by a complex mix of physical processes; turbulent flows, magnetic fields, and gravitation are thought to be the dominant effects. Determining the importance of each physical parameter requires disentangling their nonlinear interactions, which can only be studied through numerical simulations. While many groups have made high-quality simulations of the star formation process, it remains unclear how to compare the results of these high resolution simulations of star-forming regions to observational data. A method evaluating the consistency of simulations with reality is crucial. I will show how the statistical sub-field of experimental design suggests a general framework for comparing simulations and observations. Using a carefully constructed suite of simulations, I will demonstrate how this framework can be used to test different tools for comparing datasets. This reveals which methods reliably track changes in physical parameters, such as variations in the initial magnetic field, the virial parameter, or the fraction of kinetic energy found in compressive vs solenoidal modes. Our analysis finds that turbulence-based methods, such as the Spectral Correlation Function and Delta-Variance, tend to be the most sensitive tools for comparing simulations with observational data.

	Main Colloquium
Dr. Erik Rosolowsky	ORATED

University of Alberta

The star formation process is intimately linked to dense molecular gas. Extragalactic studies reveal that the luminosity of the dense gas is well correlated with the star formation rate in a system, though recent results point out that there are multiple parameters in this relationship. At smaller physical scales in our own Galaxy, we study the foundation of these broad trends by linking the structure of dense gas to actual process of star formation occurring in cores and clumps. In this talk, I will outline the unique properties of ammonia as a dense gas tracer and summarize several studies that leverage these properties. In particular, I will emphasize new results from the GBT Ammonia Survey (GAS) that highlight the ubiquity of quiescent cores and probe the connection of between cores and clouds. I will then connect those results to follow-up studies in the Galactic plane that illustrate how we can bootstrap our knowledge up to larger scales.

	Lunch Colloquium
Dr. Veselina Kalinova	ORATED

MPIfR

Circular velocity curves (CVCs) are considered one of the best tools to trace the mass distributions of galaxies. There are several indicators that the shape of the CVC, in addition to its overall amplitude, is connected to galaxy properties and internal structure. Studying 82 galaxies with diversity in morphological types, we present a dynamical classification system for galaxies based on their circular velocity curves as provided by solutions of the axisymmetric Jeans equations. We applied Principal Component Analysis (PCA) to the CVCs to find characteristics features and use k-means classifier to separate circular curves into classes. This objective classification method identifies four different classes, which we name Slow-Rising (SR), Flat (F), Sharp-Peaked (SP) and Round-Peaked (RP) circular curves. SR-CVCs are mostly represented by late-type spiral galaxies (Scd-Sd) with no prominent spheroids in the central parts and slowly rising velocities; F-CVCs span almost all morphological types (E,S0,Sab,Sb-Sbc) with flat velocity profiles at almost all radii; SP-CVCs are represented by early-type and early-type spiral galaxies (E,S0,Sb-Sbc) with prominent spheroids and sharp peaks in the central velocities. RP-CVCs are represented by only two morphological types (E,Sa-Sab) with prominent spheroids, but RP-CVCs have much rounder peaks in the central velocities than SP-CVCs. RP-CVCs are typical for high-mass galaxies, while SR-CVCs are found for low-mass galaxies. Intermediate-mass galaxies usually have F-CVCs and SP-CVCs. Circular curve classification presents an alternative to typical morphological classification and seems more tightly linked to galaxy's star formation, dark matter content and evolution.

	Lunch Colloquium
Dr. Helge Rottmann	ORATED

MPIfR

The ALMA Phasing Project (APP) is an international effort that provides the means to coherently sum all of the individual ALMA antennas, allowing them to function as a single large aperture. This capability will allow ALMA to participate in global Very Long Baseline Interferometry (VLBI) networks operating in the mm and submm regime, offering a dramatic improvement in sensitivity and resolution. Apart from VLBI, phased-ALMA will provide exciting new science capabilities in other fields, e.g., pulsar and maser searches, magnetic field studies and many others. I will present the current status of the project including results from the latest commissioning missions.

	SFB Colloquium
Dr. Michela Mapelli	ORATED

NAF - Osservatorio Astronomico di Padova, Italy

Super-massive black holes (SMBHs) give us a unique opportunity to study astrophysical processes under extreme conditions. The innermost parsecs around an SMBH should be a hostile environment for star formation. Molecular clouds are expected to be disrupted by the SMBH's tidal shear before they approach the central parsec. Thus, stars cannot form in 'normal conditions', even if the SMBH is quiescent. Despite this, we DO observe young (<<100 Myr) stars in the central parsec of our Galaxy. Furthermore, several observations suggest recent episodes of star formation in nearby galactic nuclei. Modelling the formation and the dynamical evolution of such young stars is an essential step to understand the interplay between an SMBH and its environment. In this talk, I will discuss the most recent scenarios proposed to explain the formation of stars close to SMBHs. I will show that the orbital evolution of the young stars can be used to probe the distribution of gas in the innermost parsecs of a galaxy. Finally, I will speculate on the chance of observing planets bound to SMBHs.

	Main Colloquium
Dr. Conny Aerts	ORATED

Institute of Astronomy, KU Leuven

After a basic introduction on how asteroseismology works in practice, we illustrate its application to various kinds of stars, covering the mass range from exoplanet host stars up to massive O-type stars. We show how detected oscillation modes allow us to understand details of the interior structure of stars that are impossible to unravel in any other way. The talk will focus on the major questions of how stars rotate internally and what type of angular momentum distribution they have. We end by summarizing ongoing and future projects on asteroseismology of stars that were so far not treated and highlight the potential of the Gaia and future PLATO data for this research domain.

	Lunch Colloquium
Prof. Rodion Stepanov	ORATED

ICMM Perm

Wavelet transform (WT) presents a kind of ‘local’ Fourier transform, allowing us to isolate a given structure in physical space and in the Fourier space simultaneously. A basic algorithm for 2D continuous WT has been developed as application for the "Wolfram Mathematica" package. The code has a graphical interface and is available on an MPIfR server. Outline of the talk: - Brief introduction to wavelets and general purposes of its application - Presentation of a practical application of continuous wavelet transform of two-dimensional image data, using different isotropic and anisotropic wavelet functions - General recipes how to use WT for filtration, in particular for spectral and correlation analysis, 2D structure recognition including anisotropic structures - Demonstration of wavelet transform results for artificial examples and real data of astrophysical observations.

	Main Colloquium
Dr. Mordecai-Mark Mac Low	ORATED

American Museum of Natural History

Star formation in galaxies is observed to occur in molecular clouds. However, the origins and evolution of these clouds remains unclear, impeding the construction of a predictive theory of star formation. Indeed, the necessity of molecules for star formation has come into question, as it becomes clear that their formation may just be a side effect of star formation, correlated with gravitational collapse but not causing it. In this talk I will present kiloparsec-scale, well-resolved, MHD simulations of the stratified, supernova-driven, interstellar medium performed with the Flash code. I will use the results of these simulations to argue that gravitational collapse rather than any sort of turbulent equilibrium determines the dynamics of molecular clouds, with a focus on the relationships between size, velocity dispersion, and surface density of the clouds.

	Lunch Colloquium
Dr Benjamin Magnelli	ORATED

MPIfR

In this talk, I will first review our current knowledge on the nature of the cosmic infrared background (CIB). In particular, I will explain how resolving most of the CIB at short wavelengths with Spitzer and Herschel, has improved our understanding of the cosmic dust-enshrouded star-formation activities from z~0 to z~1. However, our knowledge on the nature of galaxies responsible for the CIB at large wavelengths (lambda >250um) is still limited. I will then discuss how resolving the CIB at such wavelengths would give us essential information on the Universe at z>2 and how the next generation of large (sub)millimeter single-dish antenna could help us in this quest.

	Special Colloquium
Felicia Krauß	ORATED

Dr. Remeis Sternwarte, Universität Erlangen-Nürnberg

The IceCube Collaboration has published results on a neutrino flux significantly in excess of the atmospheric background. Due to low atmospheric background at PeV energies, the highest energy events are the most likely ones to be of extraterrestrial origin. We use broadband spectra in the IceCube integration period to calculate the maximum expected number of neutrinos assuming a simple pion photoproduction model. We find a flaring blazar in positional and temporal agreement with the highest-energy neutrino event. With this information we derive the expected hadronic contribution to the high-energy emission.