Lunch Colloquium
Dr. Laura Perez	ORATED

MPIfR

The growth of dust inside circumstellar disks is a fundamental component of the planet formation process. In the current planet formation scenario the smallest grains easily grow to larger sizes, but once macroscopic sizes are attained difficulty arises: not only collisional coagulation efficiencies drop, but the interaction of grains with the gaseous disk contributes to their demise by radial drift. Radio-wave observations -- from sub-mm to cm wavelengths -- directly trace the emission from dust of different sizes, allowing us to study their growth from micron-sized dust grains to centimeter-sized particles. I will discuss recent observational constraints of particle growth in protoplanetary disks, which are only now possible thanks to sensitive observations with radio-interferometers, particularly at cm-wavelengths with the VLA. In the systems studied, larger particles where segregated to the inner disk regions, consistent with theoretical theoretical barriers that limit further growth. A possible solution to to the posited barriers for growth exist: regions of local pressure maxima that can efficiently trap grains and create appropriate conditions for growth. I will present recent ALMA observations that reveal large-scale asymmetries in the disk dust distribution, which may be the observational signature of these regions.

	Special Colloquium
Prof Jonathan Tan	ORATED

Florida

Massive stars have played a dominant role in shaping our universe since its earliest times, but there is no consensus on the mechanism by which they form. I review the physical processes thought to be important in massive star formation, concentrating on a particular theoretical model, Turbulent Core Accretion. This assumes the initial conditions are massive, turbulent, magnetized cloud cores of gas and dust that are reasonably close to virial equilibrium. We test this via theoretical models and simulations of the physics and chemistry of the interstellar medium and observational searches for these cores. We next consider the protostellar collapse phase as a massive star grows from the core. Various forms of feedback become important in reducing the efficiency of accretion, although it is not clear if one particular mechanism operates to set a fundamental limit on the maximum stellar mass. Again, these theoretical ideas can be tested by observations of massive stars forming in our Galaxy today. Finally, I discuss an application of massive star formation theory to the early universe: how massive were the first stars and could they have been the progenitors of supermassive black holes?

	Special Colloquium
Dr. Rubén Herrero-Illana	ORATED

Instituto de Astrofísica de Andalucía (CSIC), Granada, Spain

The violent processes that take place in Luminous Infrared Galaxies (LIRGs) make them the ideal laboratories where to study both star formation and active galactic. These two processes are in fact intimately linked, and are both fuelled by molecular gas. In this talk I will explain several results obtained from different approaches: millimetre observations of molecular spectral lines, a multi-wavelength study of the central kiloparsec region of LIRGs, and especially, radio VLBI observations, which allows us to directly study the interplay between nuclear starbursts and AGN.

	Main Colloquium
Dr Markus Roth	ORATED

Kiepenheuer Institute

The Sun is subject to sound waves that probe its interior. Observations of these solar oscillations have emerged as a powerful tool to gain information on the processes in the Sun. Through helioseismology detailed inferences of the Sun's internal structure, rotation and flows can be obtained. In addition helioseismology allows studying sunspots and other magnetic active areas on the Sun which have an important impact on our technological society through the potentially harmful solar eruptions and which may play a significant role in the variations of the Earth’s climate. However, a complete understanding of the Sun, and in particular of its magnetism, can only be obtained by understanding the internal structure and properties of the stars in general. Asteroseismology offers solving this problem by studying the interiors of the stars.

	Special Colloquium
Dr. Feng Yuan	ORATED

SHAO

Black hole hot accretion flows are perhaps operating in the nuclei of most of the galaxies in our universe. In this talk, I will review the main progress in recent years in this field, which is about the wind or outflow. The progresses are mainly attributed to the rapid development of numerical simulations of accretion flows, combined with the observations of Sgr A*, the supermassive balck hole in the Galactice center. The following topics will be covered: theoretically why we believe strong winds exist; where and how they are produced and accelerated; what are their main properties such as mass flux and velocity; the comparison of the properties between wind and jet; the main observational evidences for wind, mainly from Sgr A*; and one observational manifestation of the interaction between wind and interstellar medium, namely the formation of the Fermi bubbles in the Galactic center.

	Lunch Colloquium
Pablo Torne	ORATED

MPIfR

Despite the predictions that many hundreds of pulsars should exist in the innermost part of the Galaxy, repeated pulsar surveys in the Galactic Centre have been (surprisingly) unsuccessful. However, the undeniable importance of finding pulsars in the Galactic Centre justify further and continuous efforts to survey this region. In this talk, I will briefly introduce pulsars, their importance for Galactic Centre studies, and past surveys. I will discuss the main challenges for surveying the Galactic Centre and what have we learnt from the radio-loud magnetar discovered there in 2013. Finally, two ongoing high-frequency Galactic Centre pulsar surveys carried out with the Effelsberg 100m and IRAM 30m radio telescopes will be presented, which include acceleration search to be sensitive to the most extreme pulsar-back hole systems, and make use of the highest radio frequencies ever used for such surveys.

	Special Colloquium
Dr. Theodore Gull	ORATED

Goddard Space Flight Center, Greenbelt, USA

We have intensively followed the massive binary, Eta Carinae, and its bipolar ejecta, the Homunculus, over the past 5.5-year cycle: — With HST/STIS, we mapped expanding fossil wind structures in the light of [Fe III] and [Fe II] as they responded to the hot secondary FUV for most of the cycle, and relaxed in ionization when the hot secondary plunged deeply into the very extended primary wind during periastron. — We followed the changes in He II 4686A emission across the 2014.6 periastron and find that, even though Eta Carinae is several times brighter over the last three cycles, the properties of the binary winds have not changed substantially. — With VLT/XShooter, we mapped the Homunculus in molecular hydrogen and found substructures that provide clues about the 1840s massive ejection. This is especially relevant given two recent astroph papers describing two possible scenarios leading to the 1840s massive event. Finally we present 3D print models of the Homunculus molecular hydrogen shell and of the interacting winds .. . . Made from 3D print files attached to refereed journal articles, these models prove to be both research tools and educational tools for understanding this complex system.

	Main Colloquium
Dr. Gergö Popping	ORATED

ESO

The star-formation activity of our Universe increased from early epochs (z~6), peaked around z=2, and then decreased by an order of magnitude until present age. To fully appreciate the physical origin of the star-formation activity of our Universe we need to focus on the gas content of galaxies over cosmic time. The most recent versions of cosmological models of galaxy formation explicitly include the detailed tracking of the atomic and molecular hydrogen content of galaxies and make predictions for the sub-mm lines emission from species such as CO, HCN, [CII]. New semi-empirical approaches provide data-driven predictions for the atomic and molecular gas content of galaxies. I will discuss the predictions made by these different types of models for the HI and H2 content of galaxies and their sub-mm line emission. These predictions include a weak evolution in the HI content and HI mass function of galaxies, strong evolution in the H2 content of galaxies, the weak evolution in the cosmic density of HI, the evolution of atomic and molecular gas in dark matter haloes, CO SLEDs of galaxies over cosmic time, and predictions for CO luminosity functions. I will compare these predictions to current observational samples, discuss future observing strategies, and will also demonstrate how the combination of cosmological and semi- empirical models can help to reveal caveats in our understanding of galaxy formation.

	Special Colloquium
Dr. Javier Moldón	ORATED

ASTRON

Some binary systems, from X-ray binaries to transitional millisecond pulsars, produce outflows of relativistic particles that can be detected and studied through the whole electromagnetic spectrum from low-frequency radio emission to very-high-energy gamma-ray emission, which makes them excellent natural physical laboratories. We want to understand how energy can be produced and transported so efficiently in these systems, how their energy budget is channeled away from the system, and to describe their population in the Galaxy. To answer these questions we need to push the limits of observational radio astronomy and explore new territory, as I will illustrate with two projects. First, we are using the revolutionary capabilities of the International LOFAR telescope to obtain low-frequency high-resolution VLBI images for the first time. I will show results for bright extragalactic jets that we are using to test and develop low-frequency VLBI. Second, accurate astrometry is fundamental to study any Galactic population. I will show how accurate VLBI astrometry can help us understand binary systems, and what are we doing to better plan and conduct long-term astrometric projects in the future. In summary, we are applying and developing state-of-the-art radio techniques to open new observational windows to explore relevant physical regimes. The scientific and technical outputs of these projects will have a significant impact in the exploitation of SKA during the next decades.

	Special Colloquium
Dr. Alvaro Hacar	ORATED

Institute for Astrophysics, Univ. of Vienna

Since their discovery in the early 70's, the carbon monoxide (12CO) and its less abundant isotopologues (13CO, C18O, C17O,...) have been regularly employed as tracers of the molecular structure and gas dynamics of the ISM in both local and extragalactic studies. Already in these first observations, the ground transitions of molecules like 12CO and 13CO were recognized by presenting broad linewidths that highly exceed those expected thermal FWHM at the typical gas at temperatures of 10-20K measured within GMCs. In addition to the Larson's velocity dispersion-size relationship, these suprathermal linewidths represent the observational foundation of the prevalent paradigm of the turbulent ISM. Typically overlooked in this description are the differential opacity broadening effects on the distinct CO lines. Combining large-scale observations of the three main CO isotopologue (i.e. 12CO, 13CO, and C18O) in different regions of the Taurus Molecular Cloud, we have investigated the evolution of the observed linewidths in each of these tracers as a function of their optical depths. Our results demonstrate that most of the apparently highly supersonic 12CO linewidths reported in clouds can be explain by the combination of multiple (tran-)sonic velocity components superposed along the line-of-sight, heavily saturated in the most abundant CO isotopologues. During my talk I will discuss the relevance of these findings in our current turbulent picture of molecular clouds. Reference: Hacar A., Alves, J., Burkert, A., & Goldsmith, P., 2015, submitted to A&A

	Special Colloquium
Masanori Nakamura	ORATED

ASIAA

Properties of relativistic jets are discussed from the event horizion to the galaxy cluster scales. Semi-analytical solutions and numerical simulations of MHD outflows give us a crucial understanding, but the nature of AGN jets needs to be considered in a realistic galactic environment. Multi-wave length observations provide key parameters on the BH accretion and jet dynamics in nearby LLAGNs. We argue M87, one of the most studied radio galaxies, in terms of 1) the jet formation from a spinning BH, the jet spine-sheath structure, the acceleration and collimation, superluminal motions, and the jet break as various MHD processes.

	Special Colloquium
Ms. Carolina Casadio	ORATED

Instituto de Astrofísica de Andalucía (CSIC), Granada, Spain

With the aim of understanding more about the location and mechanisms for the production of gamma-ray emission in jets of AGN, we performed multi-wavelength studies of the blazar CTA102 and the radio galaxy 3C120 during unprecedented gamma-ray flares for both sources. We also investigated the radio galaxies M87 and its peculiar feature HST-1, being a possible candidate, together with the core, for the very high energy events occurred in M87. Despite representing very different classes of AGN, the radio galaxy 3C120 and the blazar CTA102 have similar properties during gamma-ray events. The gamma-ray flares are associated with the passage of a new superluminal knot through the mm VLBI core, but not all ejections of new components lead to gamma-ray events. In both sources gamma-ray events occurred only when the new components are moving in a direction closer to our line of sight. We locate the gamma-ray dissipation zone a short distance downstream of the radio core but outside of the broad line region, suggesting synchrotron self-Compton scattering as the probable mechanism for the gamma-ray production. In addition, during the multi-wavelength outburst observed in CTA102, the optical polarized emission displayed intra-day variability and a clear clockwise rotation of the polarization vectors, which we associate with the path followed by the knot as it moves along helical magnetic field lines. A monitoring of the radio galaxy M87 with VLBA and EVN observations gave us the opportunity to follow the evolution of HST-1 during many years, resulting formed by subcomponents that move at superluminal speeds. Comparing observations with relativistic hydrodynamic simulations we obtained that HST-1 may be a decollimation shock that emits and then become visible only when new particles cross that region and are accelerated in the shock front.

	Main Colloquium
Prof. Dr. Leon Koopmans	ORATED

Groningen University

The Low Frequency Array (LOFAR) is currently the most sensitive low frequency array in the world, in part designed to detect the feeble 21-cm emission of neutral hydrogen from redshifts between z=11 and z=6, an era called the "Epoch of Reionization" (EoR). During the EoR the first (Pop III and II) stars not only ionized neutral hydrogen, but also caused radiative/mechanical feedback, enriched the ISM/IGM with metals, formed galaxies and black holes, etc. The EoR forms the foundation for much of what we see in the present-day Universe. I will review the LOFAR EoR Key Science Project that we are currently undertaking to detect this 21-cm emission, to quantify it, and to learn about new physical processes in the infant universe.

	Main Colloquium
Dr. Valentina Vacca	ORATED

MPA

A detailed knowledge of magnetic fields in the large-scale structure of the Universe is crucial to better understand cosmic magnetism. In the last decade, significant progress has been made in the characterization of the properties of magnetic fields in galaxy clusters, mainly from the study of radio halos and Faraday rotation measures of polarized radio galaxies located inside or behind these clusters. In principle, more tighten constraints on the magnetic field origin and evolution could be obtained from the study of the magnetic fields on larger scales, i.e., in filaments, voids, and sheets, before they are affected by cluster formation processes. During this talk I will give an overview on the present knowledge of intracluster magnetic fields and I will present a new statistical approach to study magnetic fields on large scales, with the rotation measure grid data that will be obtained with the new generation of radio interferometers.

	Lunch Colloquium
Giacomo Fragione	ORATED

La Sapienza University, Rome

"High velocity stars" are stars moving at velocities so high to require an acceleration mechanism involving binary systems or the presence of a massive central black hole. In the frame of a galaxy hosting a supermassive black hole (10^8 Msun), we investigated a mechanism for the production of high velocity stars between a massive, orbitally decayed, globular cluster and the supermassive black hole. Moreover, the case of close interaction between a globular cluster and a black hole binary (of total mass 10^8 Msun) is taken into account. The high velocity acquired by some stars, originally orbiting around the cluster, comes from the transfer of gravitational binding energy into kinetic energy. After the close interaction with the massive black hole(s), stars could reach a velocity sufficient to travel across the halo, or even overcome the galactic gravitational well, while some of them are just stripped from the globular cluster and start orbiting on precessing loops around the galactic centre.

	Special Colloquium
Prof. Justin Jonas	ORATED

Rhodes University

The MeerKAT is a Precursor for SKA MID and is currently under construction at the Karoo. The array will comprise 64 Gregorian offset antennas with a projected diameter of 13.5m. The array configuration is centrally concentrated, and the maximum baseline is 8km. Currently three receivers (including the MPIfR S-band receiver) are under development for MeerKAT, covering the frequency range 580 MHz to 3.5 GHz, but the antennas have a surface accuracy that will allow operation to ~20 GHz. The point-source sensitivity of the array will exceed that of the JVLA in its B, C and D configurations. Ten large legacy surveys have been allocated observing time on MeerKAT, and the science case will be refreshed after a science workshop in May 2016. The talk will outline the science and technical specifications, design process and physical implementation of the MeerKAT and associated infrastructure. The deployment schedule will be presented, together with plans for the scientific exploitation of the telescope.

	Special Colloquium
Prof. Jacques Roland	ORATED

Institut d'Astrophysique, Paris, France

I will discuss the nature and the properties of the plasma ejected by the nuclei of extragalactic radio sources and present how we can determine the structure of their nuclei using VLBI data. VLBI observations show that nuclei of extragalactic radio sources contain binary black hole (BBH) systems and I will show the link between the characteristics of the BBH systems and the RMS time series of the ICRF2 survey. To finish, I will discuss the consequences of linking VLBI observations to GAIA observations.

	Main Colloquium
Dr. Francesco de Gasperin	ORATED

Universität Hamburg

In the first part of my talk I will present the recent study of some merging galaxy clusters made with GMRT and VLA, focusing on the phenomena of radio halos, radio relics, radio phoenixes and on their interplay. The LOFAR LBA (low band antenna) norther sky survey will start in a few months. To show the potential of this survey I will present the LOFAR LBA system which is capable of observing at 30-70 MHz. Observing at these frequencies is extremely challenging and several new techniques are being developed to deal with ionospheric induced systematic errors. I will conclude presenting some preliminary LOFAR observations of galaxy clusters.

	Lunch Colloquium
Dr. Alan Roy	ORATED

MPIfR

The growing global investment in renewable energy has lead to the construction of enormous areas of solar concentrators, all of which lie idle at night. They have surface accuracies sufficient for efficient operation at gigahertz frequencies and so far four square kilometres of collecting area are operating in the form of solar power towers, which form a point focus convenient for installing a radio receiver. Following contact from Gemasolar in Spain, a few of us have been thinking how one might combine signals from their mirror field to form a single dish or interferometric array with equivalent diameter of 620 m. I will present some thoughts so far and ideas from the floor are welcome.

	Master Colloquium
Marcel Kehl	ORATED

MPIfR

This month we are celebrating the 100th anniversary of Einstein’s General Relativity. His theory is a cornerstone of modern physics and astrophysics. It is used to describe the effects of gravity in a broad range of physical systems. To be confident that our theory applies in these regimes, we have to perform precise tests. One of the best systems we know for testing General Relativity in the quasi-stationary strong-field regime is the Double Pulsar. This system has already provided unique tests for the validity of General Relativity. In my talk, I will focus on the future capabilities of this system in the SKA era using mock data simulations. In particular, I will discuss the prospects of testing quantitatively the Lense-Thirring effect for the first time outside the Solar system. Such a measurement provides a chance to constrain the moment of inertia of the neutron star PSR J0737-3039A and to restrict the equations of state for nuclear matter at ultra high densities. I will also address the role of several external contributions that have to be accounted for achieving this goal.

	Special Colloquium
Dr. Dorit Glawion	ORATED

Universität Würzburg

The AGN IC 310 has been identified as a gamma-ray emitter based on observations at very high energies (VHE, E > 100 GeV) with the MAGIC telescopes. Despite IC 310 having been classified as a radio galaxy with the jet observed at an angle > 10 degrees, it exhibits a mixture of multiwavelength properties of a radio galaxy and a blazar, possibly making it a transitional object. On the night of 12/13th of November 2012, the MAGIC telescopes observed a series of strong outbursts from the direction of IC 310 with flux-doubling time scales faster than 5 min and a peculiar spectrum spreading over two orders of magnitude. Such fast variability constrains the size of the emission region to be smaller than 20% of the gravitational radius of its central black hole possibly allowing us to probe the alleged region of jet formation. In fact, the measurement challenges the shock acceleration models, commonly used in explanation of gamma-ray radiation from active galaxies. Here, I will show that this emission can be associated with pulsar-like particle acceleration by the electric field across a magnetospheric gap at the base of the jet.

	Lunch Colloquium
Prof. Laurent Loinard	ORATED

Combining radial velocities taken from the literature with trigonometric parallaxes and proper motions measured with radio interferometers, we measured the complete 3D velocity vectors for a sample of young stars in the Taurus and Ophiuchus regions. We use them to investigate both their internal dynamics and the relative motion between the two regions. We find evidence for a significant large-scale rotation in Taurus, but no evidence for global collapse or expansion. We also find that Taurus and Ophiuchus are moving almost exactly away and must have been very near each other about 25 Myr ago. This suggests a common origin, presumably related to the local Galactic structure known as Gould's Belt.

	Special Colloquium
Dr. Naomi Hirano	ORATED

ASIAA

The object formed at the beginning of the star formation process, the first hydrostatic core (FHSC), has been predicted theoretically. Because of its short time scale, deeply embedded nature, and low luminosity, it is not easy to confirm the FHSC observationally. To date, only a handful sources are recognized as the candidates for FHSC. Two sources in the Barnard 1b (B1-b) core are bright in submm/mm wave ranges but dark in mid-IR even in the Spitzer MIPS 24 and 70 micron bands. The physical and chemical properties of these two sources have been studied with the single-dish and interferometer in the wave range from 7 mm to 0.85 mm. The very low dust temperatures of T_dust < 20 K, the low bolometric luminosities of 0.15--0.31 L_sun, the high D/H ratio of ~0.2, and low velocity molecular outflows imply that these two sources in the B1-b core are in an earlier evolutionary stage than most of the known class 0 protostars. Especially, the properties of the northern source, B1-bN, having an internal luminosity of < 0.01--0.03 L_sun, agree with those of the FHSC predicted by the numerical simulations.

	Main Colloquium
Dr. Jim Hinton	CANCELED

MPI, Heidelberg

TBD

	Lunch Colloquium
Dr. Gregory Desvignes	ORATED

MPIfR

PSR J1906+0746 is a young relativistic pulsar (discovered by the Arecibo radio telescope in 2005) in a 4-hr orbit, most likely around another neutron star. Here we report the measurement of relativistic spin-precession, an effect known to occur when the pulsar spin axis is misaligned with respect to the orbital angular momentum vector, that makes our line of sight cut different part of the radio beam. Using observations from the Arecibo, Green Bank and Nancay radio telescopes from 2005 to 2009, we detected severe pulse profile variations, leading towards the disappearance of the pulsar from our line of sight. Modeling the polarimetric data to the Rotating Vector Model (RVM), we determined the geometry of the system and confirmed that our line of sight is moving away from the center of the pulsar's radio beam. We also derived a tentative model for the radio beam shape and made predictions for its reappearance.

	SFB Colloquium
Dr. Amy Kimball	ORATED

CASS, Sydney

I will present ALMA observations of some of the most luminous quasi-stellar objects (QSOs) known, investigating their far-infrared emission and discussing an extremely broad and luminous double-peaked [CII] line in a QSO at redshift z=4.6. The parent sample was compiled from multi-wavelength sky survey data, with which we were able to identify the most luminous (unobscured) QSOs in the Universe. Of over 100,000 broad-line quasars identified in the SDSS, just 90 have bolometric luminosities greater than 10^14 solar luminosities (as or more luminous than the most luminous obscured quasars currently known). We are for the first time determining the far-infrared continuum of this extremely luminous population. In addition, an unusually broad [CII] line observed in one target suggests a massive rotating disk in place at redshift z=4.6, with implications for the high-redshift M-sigma relation.

	Master Colloquium
Aida Ahmadi	ORATED

MPIfR

The Galactic center is an excellent laboratory for studying a galactic nucleus at high spatial resolutions. The molecular gas in the inner ~ 500 pc of the Galaxy, called the Central Molecular Zone (CMZ), is different from the gas found in the disk of the Galaxy. In the CMZ, the gas is on average much hotter, denser, and more turbulent. Due to the existence of a thin, warm, and diffuse intercloud medium in the CMZ, surveys of CO fail to tell us much about the morphology of individual gas clumps. Therefore, it has been evident for some time that to understand the physical conditions in this region, surveys in rarer, less abundant molecules are required. We have combined molecular line spectra from the Mopra telescope at 3-mm with observations of 14 sources using the APEX telescope in the sub-mm regime in order to cover multiple lines in a few molecular species. We modelled several lines in H2CO, C3H2, HC3N, H13CO+, HN13C, and HNC with RADEX under non-LTE conditions and derived constraints on the gas temperatures and densities in these regions. We find high gas temperatures in the range of ~ 90 - 140 K, much higher than the average dust temperature of 20 K derived from Herschel maps of the CMZ. This decoupling between the gas and dust temperatures would mean that the gas is not heated by collisions with dust and some other heating mechanism must exist in the Galactic center. We find gas densities higher than 6X10^4 cm^-3 and will also briefly discuss discrepancies between the gas-derived and dust-derived densities.

	Lunch Colloquium
Eric Jiménez-Andrade	ORATED

AIfA

I present some results related with my master thesis in collaboration with the AGN’s group at INAOE (Mexico). We carried out an observational study of PKS 0521-365 by using optical spectroscopy (FORS2, VLT) and high-resolution imaging (WFC2/HST). We find signatures of ionized clouds along the jet direction moving at ~100 km/s in a helicoidal fashion and extending beyond to 20 kpc. Along the direction of the major axis we detect an outflow moving with a maximum projected velocity of ~400 km/s (at 3 kpc). We discuss our results on the context of AGN feedback and galaxy evolution.

	Master Colloquium
Hans Nguyen	ORATED

MPIfR

The main of objective of the GLOSTAR survey is to provide a GLObal view on STAR formation in our galaxy. Through a combination of radio, submm and IR data, the project will provide information on the distances, composition, luminosities and masses, thus describing a complete picture of massive star formation and Galactic structure. To this end, the study of the interstellar medium is integral as it is the birthplace of new stars. The main constituent however is molecular hydrogen which cannot be directly observed. As such, an indirect probe is required. The formaldehyde 110-111 ground state transition line at 4.8~GHz fulfills this role. It is adept at probing the kinetic temperature and spatial density of molecular clouds. Furthermore, they are known to be good tracers of HII regions, regions with known associations to star forming regions. I present now the work done to detect sources of formaldehyde in the Galactic midplane. A source extraction code was written to detect formaldehyde emission and absorption in the range of 28 < l < 36 degrees and -1 < b < 1 degrees. I compare the code to the known DUCHAMP search program. I report on the 17 absorption detections found on which two sources have ancillary APEX data from which the optical depth is calculated and the spatial density and kinematic temperature estimated.

	Master Colloquium
Laura Vega García	ORATED

MPIfR

Space VLBI observations with RadioAstron provide an extraordinary improvement of angular resolution. In this talk, I will present the results obtained from RadioAstron imaging of the quasar 0836+710 at L, C, and K bands. The images of 0836+710 show a wealth of structure on scales ranging from 0.2 to 150 milliarcseconds, which enables detailed studies of shocks and plasma instability development in the jet. Our preliminary analysis shows that the observed structure is consistent with a jet which has a lower density than the surrounding medium and propagates with a Mach number of ~6. Further modelling of the internal structure of the flow should yield a more detailed physical picture of the jet propagation.

	Special Colloquium
Dr. Torsten Enßlin	ORATED

MPA Garching

Information field theory (IFT) describes probabilistic image reconstruction from incomplete and noisy data. Based on field theoretical concepts IFT provides optimal methods to generate images exploiting all available information. Applications in cosmology and astrophysics are CMB analysis (non-Gaussianities, Gaussianities), galactic tomography, as well as gamma- and radio-astronomical imaging. A novel IFT-based gamma ray sky image derived from data of the Fermi-satellite provides insights into the high energy properties of the Milky Way.

	Main Colloquium
Dr. Eiichiro Komatsu	ORATED

MPA

Statistical properties of the observed fluctuations of temperature and polarisation anisotropies of the cosmic microwave background are remarkably consistent with the basic predictions of cosmic inflation driven by a single energy component. The observed fluctuations are Gaussian and adiabatic, and the strength of fluctuations weakly depends on spatial scales. The WMAP experiment has confirmed these predictions with precision, and the Planck experiment has further tightened the limits on deviations from Gaussianity and adiabaticity of fluctuations. So, has inflation really happened? We do not know yet. A definitive observational proof of inflation must come from a convincing detection of signatures of nearly-scale-invariant primordial gravitational waves generated during inflation. The so-called B-mode polarisation of the cosmic microwave background is the most promising method known to date to detect such gravitational waves. In this presentation, we first briefly review the physics of E- and B-mode polarisation of the cosmic microwave background. We then discuss how to measure these signals in the data in the presence of Galactic foreground and gravitational lensing. A simple analysis shows that it is possible to detect a faint B-mode signal at the level of the tensor-to-scalar ratio of 0.001, i.e., two orders of magnitude below the current limit set by the temperature anisotropy data. This is likely the smallest tensor-to-scalar ratio we would ever reach using the cosmic microwave background. Detection of nearly scale-invariant B-modes at this level or above provides a definitive proof of inflation happening at “high-scales,” i.e., energy scales close to a grand unification scale, 10^16 GeV.

	Lunch Colloquium
PD Dr. Rainer Mauersberger	ORATED

MPIfR

To most people (including professional radio astronomers) the concept of using a digital correlator to combine signals from different antennas to construct images is all all intuitive. I will describe the many similarities between stereophonic hearing and interferometry, as we are doing it with ALMA, PdB or VLBI. I will describe how sound waves arrive in our ears with a difference in phase, how these signals are frequency separated and digitized and, finally, transmitted via nerves with different lengths to special cells in the brain that can perform a multiplication of two incoming digital datastreams from each of your two ears. Thus, when ALMA takes one of its stunning images its nothing else than we do when enjoying a concert with closed eyes and nevertheless distingishing the frequencies and eroslocations of each instrument. I will also address another capability of our auditory system, namely to mix signals with slightly different frequencies, and thus "hear" a signal with the difference frequency of the two incoming signals.

	Main Colloquium
Prof. Dr. Matthias Bartelmann	ORATED

Institut für Theoretische Astrophysik, Heidelberg

So far, the non-linear evolution of cosmic structures is accessible only for large-scale numerical simulations. The conventional analytic treatment of cosmic density fluctuations with the hydrodynamical equations runs into severe conceptual and technical difficulties even on moderately non-linear scales. As an alternative, we have developed a microscopic, non-equilibrium, statistical theory for cosmic structure formation which avoids these difficulties by construction and allows to enter deeply into the non-linear regime of cosmic density fluctuations. The theory also allows to unify approaches to kinetic theory and hydrodynamics, offering a joint treatment of dark and baryonic matter. I will motivate and introduce this theory in simple terms, show some results on non-linear cosmic structure formation obtained so far, and discuss some possible future applications.

	Main Colloquium
PD Dr. Christoph Pfrommer	ORATED

HITS, Heidelberg

Understanding the physics of galaxy formation is arguably among the greatest problems in modern astrophysics. Recent cosmological simulations have demonstrated that "feedback" by star formation, supernovae and active galactic nuclei appears to be critical in obtaining realistic disk galaxies, to slow down star formation to the small observed rates, to move gas and metals out of galaxies into the intergalactic medium, and to balance radiative cooling of the low-entropy gas at the centers of galaxy clusters. However the particular physical processes underlying this "feedback" still remain elusive. In particular, these simulations neglected cosmic rays and magnetic fields, which provide a comparable pressure support in comparison to turbulence in our Galaxy, and are known to couple dynamically and thermally to the gas. Using hydrodynamic simulations of galaxy formation, I will show how cosmic rays are able to drive powerful galactic winds in low-mass galaxies. This reduces the available amount of gas for star formation and implies a shallower slope of the faint-end of the galaxy luminosity function as required by observations. In the second part of the talk I demonstrate that cosmic-ray heating can balance radiative cooling of the low-entropy gas at the centers of galaxy clusters and helps in mitigating the star formation of the brightest cluster galaxies. New data on the low-frequency radio and gamma-ray emission of M87, the closest active galaxy interacting with the cooling cluster plasma, enable us to put forward a comprehensive, physics-based model of feedback by active galactic nuclei.

	Master Colloquium
Asmita Bhandare	ORATED

MPIfR

Supervisor : Prof. Susanne Pfalzner (MPIfR), Prof. Pavel Kroupa (AIfA) Most young stars are initially surrounded by protoplanetary discs. Owing to the preferential formation of stars in stellar clusters, the protoplanetary discs around these stars potentially may be affected by the cluster environment. Various works have investigated the influence of stellar fly-bys on discs, although most of them consider only the effects due to parabolic, coplanar encounters often for equal-mass stars, which is only a special case. We perform numerical simulations to study the fate of protoplanetary discs due to the impact of parabolic star-disc encounter for the less investigated case of inclined and retrograde encounters. Here we concentrate on the disc size after such encounters for different periastron distances and mass ratios. We find that despite the prograde, coplanar encounters having the strongest effect on the disc size, inclined and even the least destructive retrograde encounters mostly also have a considerable effect especially for close periastron passages. Interestingly, we find a linear dependence of the disc size on the orbital inclination for the prograde encounters but not for the retrograde case. We also determine the final orbital parameters of the particles in the disc such as eccentricities, inclinations and semi-major axes. Using this information the presented study can not only be used to describe the fate of discs but also that of planetary systems after inclined encounters. In a follow up study we will investigate the possible connection between non-coplanar encounters and Sedna-like objects in our Solar System.

	Lunch Colloquium
Dr. Talayeh Hezareh	ORATED

MPIfR

The next World Radio Conference (WRC) will be held this November in Geneva. A number of agenda items involving all radio services have been developed and heavily discussed since the last WRC in 2012 and all countries in the world have now finalised their positions on these existing agenda. I will provide an overview of the issues relevant to radio astronomy for this conference and also the proposals submitted and approved for the next conference in 2019.

	Main Colloquium
Prof. Dr. Andreas Burkert	CANCELED

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.

	Special Colloquium
Tigran Arshakian	ORATED

University of Cologne

Mapping observations of molecular clouds in different chemical tracers, different transitions of the same tracer or different velocity channels within one transition reveal structural changes in the clouds such as phase transitions, temperature profiles, and patterns of turbulent velocities. We present a wavelet-based weighted cross-correlation (WWCC) method to study the correlation between two maps of a turbulent molecular cloud and displacement between their structures as a function of scale, in which no assumption about the noise or boundaries are made. The method includes a weighting function that allows us to deal with non-uniform noise often present in the maps. The WWCC is a powerful statistical tool allowing us to compare different maps and trace scales with prominent or enhanced structures, chemical and phase transitions, providing insight into the physical conditions of interstellar gas. The WWCC is tested for simulated maps containing circular and self-similar structures. I will discuss the advantages and limitations of the WWCC, results of its application to simulated MHD maps, and observed emission line maps of the giant molecular cloud G 333.

	Lunch Colloquium
Daniel Lenz	ORATED

AIfA

The IRAS discovery of infrared cirrus clouds was the starting point of correlation studies of neutral atomic hydrogen and dust far-infrared emission. These yield important insights into the gas and dust physics, the accretion history of the Milky Way, the X_CO factor, and the distribution of the CO-dark molecular gas. So far, full-sky analyses were limited by the angular resolution of the HI data of about one degree. The recently finished Effelsberg-Bonn HI Survey (EBHIS) improved this limit by an order of magnitude. Here, we aim to consistently quantify the relation between dust and gas, using the most accurate full-sky data sets. Moreover, a Bayesian framework and state-of-the-art methods of inference and image analyses allow us to deduce all-sky maps of e.g. the X_CO factor, dust emissivity, (CO-dark) molecular gas and the Cosmic Infrared Background. We present the first results of this work and compare our results with targeted observations.

	Main Colloquium
Prof. I. Papadakis	CANCELED

Department of Physics and Institute for Plasma Physics, University of Crete

TBA

	Main Colloquium
G. Panopoulou	ORATED

Department of Physics and Institute for Plasma Physics, University of Crete

The stages before the formation of stars in molecular clouds are poorly understood. Insights can be gained by studying the properties of quiescent clouds, such as their magnetic field structure. The plane-of-the-sky orientation of the field can be traced by polarized starlight. We present the first extended, wide-field (∼10 deg2 ) map of the Polaris Flare cloud in dust-absorption induced optical polarization of background stars, using the RoboPol polarimeter at the Skinakas Observatory. This is the first application of the wide-field imaging capabilities of RoboPol. Our analysis resulted in reliable measurements of 641 stars with median fractional linear polarization 1.3%. The projected magnetic field shows a large scale ordered pattern and appears to align with faint striations seen in the Herschel-SPIRE map of dust emission (250 μm). The overall polarization pattern we obtain is in good agreement with large scale measurements by Planck of the dust emission polarization in the same area of the sky.

	Main Colloquium
Dr. Talvikki Hovatta	ORATED

Aalto University Metsähovi Radio Observatory

Our knowledge of the very-high emitting (> 100 GeV) gamma-ray sky has increased tremendously thanks to the current generation imaging air cherenkov telescopes MAGIC, VERITAS and HESS. Currently there are over 50 blazars detected by these instruments compared to only six in 2003, enabling population studies for the first time. In the majority of these blazars, the synchrotron emission peaks at X-ray energies so that they are classified as high-synchrotron peaked (HSP) objects. However, not all HSP blazars are detected at the very high energies and our aim is to study if there are differences in their intrinsic properties, or if all HSP blazars are similar and could be detected with more sensitive instruments, such as the Cherenkov Telescope Array. In 2014 we observed a sample of 38 TeV-detected blazars in optical polarisation using the RoboPol instrument in Crete and the Nordic Optical Telescope in Spain. We have compared the optical polarization properties and variability of these TeV-detected blazars with other non-TeV objects in the RoboPol sample. In this talk I will review the general variability properties of these objects in the optical and radio bands when compared to other types of blazars. I will also present the first results from the optical polarization study.

	Main Colloquium
Dr. D. Blinov	ORATED

Department of Physics and Institute for Plasma Physics, University of Crete & Astronomical Institute, St. Petersburg State Unive

We present our results on polarisation swings in optical emission of blazars obtained by RoboPol, the first monitoring program of an unbiased sample of gamma-ray bright blazars specially designed for effective detection of such events. A possible connection of polarization swing events with periods of high activity in gamma-rays is investigated using the data set obtained during the 1st season of operation. We conclude that: the full set of observed rotations is not a likely outcome of a random walk of the polarization vector simulated by a multicell model; furthermore, it is highly unlikely (more than 4 sigma) that none of our rotations is physically connected to an increase in gamma-ray activity; the brightest gamma-ray flares tend to be located closer in time to rotation events, which may be an indication of two separate mechanisms responsible for the rotations; finally, blazars with detected rotations during non-rotating periods have significantly larger amplitude and faster variations of polarization angle in optical than blazars without rotations.

	Main Colloquium
Prof. A. N. Ramaprakash	ORATED

Inter-University Centre for Astronomy and Astrophysics (IUCAA), India

TBA

	Lunch Colloquium
Dr. Rusen Lu	ORATED

MPIfR

In recent years, significant progress in millimeter VLBI has been made with the Event Horizon Telescope project, which aims to resolve strong field General Relativistic (GR) signatures in nearby supermassive black holes (in particular Sgr A* and M87). The first part of this talk will deal with the question of whether or not these signatures can be imaged when the radio emission from Sgr A* exhibits variability on timescales of minutes, much shorter than the duration of a typical VLBI imaging experiment. The second part will focus on the first 230 GHz VLBI observations of Sgr A* with the APEX telescope in 2013. With a resolution of 3 Schwarzschild radii, these observations reveal “complex” structures that have never been seen before. With the expected improvement in array performance, future observations could lead to direct detection of strong GR signatures, e.g., the black hole shadow.

	Main Colloquium
Dr. Jason Dexter	ORATED

MPE

The Galactic center black hole, Sgr A*, provides a remarkable opportunity to study strong gravity using either orbiting stars or accreting gas. Very long baseline interferometry observations at millimeter wavelengths are now spatially resolving event horizon scales around Sgr A*, and near-infrared astrometry with the VLTI instrument GRAVITY will achieve similar resolution in the next few years. In both cases, interpreting the data requires physical modeling. I will discuss the construction of relativistic emission models from numerical simulations of black hole accretion flows and jets, what we've learned from their comparison with current data, and the prospects for detecting signatures of strong gravity (e.g., the black hole "shadow") in future observations. I will also argue that the recent discovery of a rare magnetar outburst near Sgr A* implies the presence of an unusual pulsar population in the Galactic center.

	Lunch Colloquium
Prof. Dr. Susanne Pfalzner	ORATED

MPIfR

The life time of protoplanetary discs is usually determined from the disc frequencies in young stellar clusters of different ages. Observational studies seem to show that the disk frequency decreases rapidly with cluster age with <10% of cluster stars retaining their disks for longer than 2-6 Myr. This would imply extremely fast disk dispersal and rapid planet growth. Here we question the validity of this constraint by demonstrating that the short disk dissipation times inferred to date might have been heavily underestimated by selection effects. In fact, the higher disk fractions in co-moving groups indicate that it is likely that over 30% of all field stars retain their disks well beyond 10 Myr, leaving ample time for planet growth.

	Special Colloquium
Dr. Andrew Walsh	ORATED

Department of Physics and Astronomy, Curtin University, Perth

The Centre of our Galaxy - the Central Molecular Zone (CMZ), contains 80% of all dense gas in the Galaxy, but holds only about 5% of current star formation. The CMZ is hotter, denser and more turbulent than anywhere else in the Galaxy. It is a truly unique place. It is also important as the CMZ has analogues in other galaxies that are typically used to estimate extragalactic star formation rates. Yet we do not understand the star formation in the CMZ. I will describe the CMZ and present recent models to explain the unusual star formation. I will also introduce a way to make a 3 dimensional model of the CMZ with the hope that this can be used to help us understand how star formation proceeds under extreme circumstances.

	Main Colloquium
Dr. Mark Heyer	ORATED

University of Massachusetts

Turbulence within star forming regions of the Milky Way is generally inferred from supersonic velocity dispersions measured in the line profiles of molecular line emission, most notably, the millimeter rotational transitions of 12CO and 13CO. Our ability to measure and quantify turbulent motions in molecular clouds has been enhanced in recent years. First, heterodyne focal plane arrays at millimeter wavelengths on moderate to large telescopes enable wide-field spectroscopic imaging of molecular line emission. Second, analysis tools have been developed that exploit the velocity information resident within the produced data cubes. In my presentation, I will review these efforts with attention towards the velocity spectrum of turbulence within well-resolved molecular clouds. These results are extended to the cloud-to-cloud integrated size-line width relationship. A fundamental plane for molecular clouds emerges from the near universality of the turbulence in molecular clouds and the equipartition between gravitational and turbulent kinetic energy densities. While the size-line width relationships offer insights to phenomenological descriptions of turbulence, these do not identify the physical origin of cloud motions within molecular clouds. I will present recent 1mm and 3mm imaging of CO lines in the low column density (Av ~ 1) envelope of the Taurus cloud that reveals wave-like motions of molecular gas responsible for the observed striae aligned along the local magnetic field direction. Many of the observed features can be explained by the propagation of magneto-sonic waves across the cloud.

	Main Colloquium
Prof. Dr. Eva Grebel	ORATED

Heidelberg

Dwarf galaxies are the most common type of galaxy in the Universe and include the most dark-matter-dominated objects known. They offer intriguing insights into evolutionary processes at low halo masses and low metallicities. Moreover, as survivors of a once much more numerous population of building blocks of larger galaxies, they are key to understanding very early star formation processes. The Local Group and particularly the Milky Way's dwarf galaxy entourage offer us the unique possibility to compare in detail dwarf and Galactic populations. This is an important step towards quantifying the magnitude and time scales of dwarf contributions to the build-up of the Milky Way and allows us to test predictions of cosmological theories and hierarchical structure formation.

	Special Colloquium
Dr. Niels Oppermann	ORATED

University of Toronto

Magnetic fields are thought to pervade all environments in the Universe. However, they are notoriously hard to understand or even observe. One observable that is sensitive to magnetic fields is the Faraday rotation experienced by linearly polarized light. This probes magnetic fields anywhere on the line of sight between the source and the observer. For extragalactic sources, this means that we are provided with an observable that contains, in principle, information on the magnetization of a vast array of environments: the interstellar medium in the Milky Way and the source galaxies, the intergalactic medium within galaxy clusters, the low-density medium in large-scale structure filaments, sheets, and voids. However, all this information is tightly entangled in the observations. I will discuss statistical models that can be used to disentangle the different contributions and show that these, in combination with upcoming LOFAR and SKA observations, will enable the detection of very weak cosmic-scale magnetic fields, thus potentially shedding light on the origin of cosmic magnetism.

	Special Colloquium
Dr. John Whelan	ORATED

Max Planck Institute for Gravitational Physics (Albert Einstein Institute)

The low-mass x-ray binary (LMXB) Scorpius X-1 (Sco X-1, presumed to be a binary consisting of a neutron star which is accreting matter from a low-mass companion) is one of the most promising potential sources of gravitational waves (GWs) which may be observed by the generation of GW detectors---such as Advanced LIGO, Advanced Virgo and KAGRA---which will begin operation this year with the first Advanced LIGO observing run, and Advanced Virgo and KAGRA observations expected to follow in the coming years. Nonaxisymmetric deformations in the neutron star can give rise to gravitational radiation, most of which is emitted at twice the rotation frequency of the neutron star. Such deformations can be maintained by the accretion of matter onto the neutron star. It has been conjectured (e.g., by Bildsten in 1998) that the neutron star's rotation may be in an approximate equilibrium state, where the spin-up torque due to accretion is balanced by the spin-down due to GWs. Scorpius X -1's high x-ray flux implies a high accretion rate, which makes it the most promising potential source of observable GWs among known LMXBs. Since Sco X-1 is not seen as a pulsar, its rotation frequency is unknown. There is also residual uncertainty in the orbital parameters which determine the Doppler modulation of the signal, monochromatic in the neutron star's rest frame, which reaches the solar-system barycenter. This parameter uncertainty limits the effectiveness of the optimal coherent search for periodic GWs, as the parameter space resolution needed for a fully coherent search renders the projected computing costs

	Special Colloquium
Dr. Rupal Mittal	ORATED

Max Planck Institute for Gravitational Physics (Albert Einstein Institute)

A short gas cooling-time owing to radiative losses at the centers of galaxy clusters should lead to a massive reservoir of cold molecular gas and extreme star formation rates. Observations, on the other hand, are consistent with cooling at only 10% of the expected level. A globally-stable feedback heating mechanism is essential to prevent the otherwise massive cooling expected of the intracluster medium. AGN heating is a viable mechanism capable of ensuring such stability. Despite AGN heating, however, a number of central galaxy clusters show evidence of some star formation. These galaxies also exhibit a multi-phase medium as manifested by the presence of an intricate network of H-alpha filaments, warm CO, diffuse ionized far-infrared line emission and continuous dust emission. In the first half of my talk, I will discuss these observations in light of current self-regulated feedback theories. In the second half of my talk, I will discuss the issue of accurate determination of star formation rates in brightest cluster galaxies (BCGs) in cool-core systems. I will describe a study (Mittal, Whelan and Combes 2015) in which we used broad-band imaging data for a sample of 10 cool-core BCGs and conducted a Bayesian analysis with the help of stellar population synthesis (SPS) to determine the likely properties of the constituent stellar populations. Robust determination of star formation rates in BCGs has a direct impact on our understanding of cooling of the ICM, star formation and AGN-regulated feedback. It is important to understand the degeneracies among the physical properties parameterizing the stellar populations, in particular, the young stellar population, so that we may better understand its connection to the gas cooling out of the intracluster medium.

	Special Colloquium
Prof John Bally	ORATED

Colorado

Dynamical processes responsible for the ejection of massive stars from their birth-sites as high-velocity runaway stars may be responsible for the most powerful protostellar outflows. The OMC1 outflow, located immediately behind the Orion Nebula, may have been triggered by the dynamic interaction of a non-hierarchical system of massive stars that formed a compact binary, ejected the binary (suspected to be radio source I) and the 15 Solar mass BN object, and released ~10^48 ergs of energy about 500 years ago. Explosive outflows similar to Orion may be associated with the ejection of runaway stars, produce IR-flares with luminosities between novae and supernovae, and have profound feedback impact on their parent molecular clouds. I will present multi-conjugate adaptive optics imaging with the Gemini-South 8-meter telescope at 0.06" resolution images of the 2.12 micro-meter H2 and 1.64 micro-meter [FeII] emission from the shock-excited fingers and results from or ALMA Cycle 2 observations of CO, SiO, SO, and the continuum with 1" angular resolution. I will also discuss the first results of a Spitzer warm-mission program (SPIRITS) which is searching for IR-only transients, acme of which may be similar to the Orion event, in ~200 nearby galaxies.

	Special Colloquium
Prof. Dr. Daisuke Nagai	ORATED

Yale University

Galaxy clusters are the largest and most recently formed cosmological objects in the universe, making them powerful laboratories for cosmology and astrophysics. The current generation of multi-wavelength cluster surveys have dramatically increased the sample size and the image quality of observed galaxy clusters out to high-redshift. However, the statistical power of these surveys are limited by complex and still poorly understood cluster astrophysics that shape their observable properties and evolution. In this talk, I will present recent advances in our understanding of cluster astrophysics (with highlights on the emerging area in the outskirts of galaxy clusters) and discuss outstanding challenges and future prospects for the use of galaxy clusters as a cosmological probe.

	Special Colloquium
Dr. Matthias Kaminski	ORATED

Dept of Physics & Astronomy, University of Alabama

Observations show that, at the beginning of their existence, neutron stars are accelerated briskly to velocities of up to 1000 km/s. We will devote a third of this colloquium to a review of the observations, simulations, and some previous theoretical models. After that, we will introduce a rather simple theoretical explanation capable of accounting for these kicks in a systematic effective-field-theory framework. Anomalies of the Standard Model of particle physics result in chiral transport terms in this effective (hydrodynamic) description. We will identify this chiral transport as an explanation for the drastic acceleration of neutron stars during the first few seconds of their existence. Finally, we are going to discuss possible implications for observations.

	Special Colloquium
Craig Anderson	ORATED

Sydney University

When linearly polarised radiation passes through a magnetised plasma, Faraday rotation encodes information about its magnetoionic structure as frequency dependent changes in the complex polarisation vector that characterizes the radiation. As a result, radio observations of distant AGN have been used to probe magnetised plasmas throughout the cosmos, from the inner regions of AGN themselves right through to Earth's ionosphere. For many years, the physical properties of these plasmas were derived from 'rotation measures' --- the gradient of a linear fit to the polarisation angle vs. the square of the observing wavelength. However, modern observations have revealed that the polarised emission from many extragalactic sources cannot be well described by a single RM, but instead exhibits 'Faraday complexity' - complicated changes in polarisation that betray the presence of complicated magnetoionic structures along the line of sight to the source. The idea that measuring and modelling this Faraday complexity might reveal a great deal more magnetised source structure than rotation measures alone has been with us since at least the sixties. However, it has only been recently that telescopes have achieved the wide observing bands required to make routine use of these insights. In this talk, I will discuss the result of two broadband polarisation surveys that we have undertaken with the goal of observing and characterising Faraday complex polarisation behaviour in discrete radio sources. I will show how Faraday complexity is readily detected in a substantial proportion of radio sources, and how this complexity reveals the existence and properties of complicated magnetised structures in our Milky Way's interstellar medium, galaxy clusters and the inner regions of AGN themselves (among other things).

	SFB Colloquium
Dr. Genevieve Parmentier	ORATED

Astronomisches Rechen-Institut, Heidelberg

Star clusters constitute a major channel of star formation in the local Universe. And as groups of largely coeval stars, they can be detected against the background of their host galaxy, and age-dated. They are therefore vital tracers of the process of star formation, as well as of the history of galaxies. As time goes by, however, star clusters steadily lose their stars and, eventually, get completely dissolved, a process which depends sensitively on their formation conditions. A thorough understanding of cluster formation conditions is therefore urgently needed to reconstruct the star formation history of galaxies from the encoded record left by their surviving star clusters. In this presentation, I will show how the properties of star cluster systems can be exploited to probe into the formation conditions of star clusters. Specifically, I will build on the evolution with time of the cluster mass distribution to constrain the mass-radius relation of clusters at birth, and to explain the limit for massive star formation observed in the mass-radius space of molecular structures. These results have stimulated the development of a new model for cluster formation. Not only is this model able to explain the steep relation between the local surface densities of molecular gas and young stellar objects of the Solar Neighbourhood, it has also prompted us to reassess the ability of clusters to survive the expulsion of their residual star-forming gas. Stellar age spreads in clusters as a function of their mean volume density will also be discussed.

	Main Colloquium
Prof. P. Janardhan	ORATED

Physical Research Laboratory, Ahmedabad, India

A study of solar photospheric fields and solar wind micro-turbulence in the inner heliosphere suggests that we are headed towards a prolonged period of little/no sunspot activity similar to the well-known Maunder minimum between 1645 and 1715. Our observations of a steady 20 year decline of solar high latitude magnetic fields, starting from ~1995, combined with the fact that cycle 24 is already past its peak, implies that solar polar magnetic fields will continue to decline until ~2020, the minimum of cycle 24, and will fall to very low values if the trend continues into solar cycle 25. In addition, extensive 327 MHz interplanetary scintillation (IPS) observations (1983-2013) from the IPS network of the Solar Terrestrial Environmental Laboratory (STEL), Japan, have shown that solar wind micro-turbulence levels in the inner-heliosphere have also been steadily declining, in sync with the declining solar photospheric fields. The large scale IPS signature in the inner heliosphere and the declining solar polar fields provide a consistent result, indicating the possibility of the onset of a long period of very low sunspot activity. An assessment of the possible impact of such a decline on terrestrial ionospheric current systems suggests that the night time ionospheric cut-off will drop well below 10 MHz. The period post 2020 would thus be very useful for undertaking systematic ground-based low-frequency radio astronomy studies.

	Lunch Colloquium
Dr. Florian Pacaud	ORATED

AIfA

The XXL survey is the largest observing program ever performed with ESA's XMM-Newton satellite. It aims at mapping 50deg2 of the sky at high galactic latitudes to study the large-scale-structures of the Universe through the distribution of galaxy clusters and active galactic nuclei. The flagship goal of the survey is to use the cluster number density, mass distribution and two-point correlation function to obtain competitive constraints on the equation of state of dark energy. In this presentation, I will briefly present the project and discuss the first scientific results on galaxy clusters which are about to be released.

	Main Colloquium
Dr. Markos Georganopoulos	ORATED

University of Maryland, Baltimore County, USA

The Chandra X-ray observatory has discovered dozens of resolved, kiloparsec-scale jets associated with powerful quasars in which the X-ray fluxes are observed to be much higher than the expected level based on the radio-optical synchrotron spectrum. The most popular explanation for the anomalously high and hard X-ray fluxes is that these jets do not decelerate significantly by the kiloparsec scale, but rather remain highly relativistic (Lorentz factors Gamma ~ 10). By adopting a small angle to the line-of-sight, the X-rays can thus be explained by inverse Compton up-scattering of CMB photons (IC/CMB), where the observed emission is strongly Doppler boosted. Using over six years of Fermi monitoring data, we show that the expected hard, steady gamma-ray emission required by the IC/CMB model is not seen in PKS 0637-752, the prototype jet for which this model was first proposed. IC/CMB emission is thus ruled out as the source of the X-rays, joining recent results for the jets in 3C 273 (using the same method; Meyer et al. 2014) and PKS 1136-135 (using UV polarization; Cara et al., 2013). This limits the jet maximum speed and suggests that the X-rays are synchrotron radiation from up to 100 TeV electrons accelerated in situ. These have interesting implications: the angle-integrated radiation from the large scale jet may be at a level similar to that of the blazar, making the large scale jet as lossy as the base of the jet, and the angle integrated TeV emission produced by a large scale jet may exceed that of a typical TeV BL Lac, possibly making large scale jets an important source of TeV photons in the Universe.

	Special Colloquium
Dr. Eileen Meyer	ORATED

STScI

The long operating lifetime of Hubble has resulted in an increasingly valuable archive of images of AGN jets taken over the last twenty years. With recent advances in state-of-the-art astrometric methods, we can now leverage this archive to measure the motions of the relativistic plasma in these jets in galaxies as distant as 500 Mpc, reaching accuracies of: 10% the speed of light. I will present recent discoveries, including the unwinding of helical kpc-scale structure in M87, and an internal shock collision in action in 3C 264 (Meyer et al., 2015, Nature) as well proper motions and their implications for jet physics for other nearby radio galaxies. I will discuss the advances in technique which have enabled even very short exposures (e.g. early WFPC2 “snapshot” images) to be registered using background galaxies, and discuss future observations which will continue to push the envelope of HST proper-motions science.

	SFB Colloquium
Dr. Charles Steinhardt	ORATED

Cal Tech

Initial results from SPLASH, an ultra-deep multi-wavelength survey, allow a study of star formation out to z~6. Combining these results with dozens of star formation and supermassive black hole accretion studies, there is a consistent picture of galactic evolution at 0 < z < 6. These results also create tension with hierarchical merging at high redshift. We can define a "synchronization timescale" for galaxies as a measure of the uniformity of an ensemble of galaxies at various cosmic epochs. If galaxy evolution is dominated by stochastic processes, then galactic events occurring at high redshift should happen at nearly the same time across an ensemble of galaxies, while events occurring at low redshift should be much less synchronous. Surprisingly, this synchronization timescale is both mass- and time-independent, a constant 1.4 Gyr for all combinations of mass and time. As a result, we are prompted to consider a framework for galactic evolution along a main sequence so that star formation, supermassive black hole accretion, and feedback between the two are dominated by deterministic rather than stochastic processes.

	Lunch Colloquium
Prof. Dr. Bernd Klein	ORATED

MPIfR

Many developments in radio astronomy are increasingly dependent on digital signal processing. The new founded department will focus on actual and future trends in digital hardware, gate- and software to support the other technical divisions with innovative digital solutions. In my talk I will introduce the new division and report on the latest generation of broadband FFT spectrometer as well as the ongoing digital developments for the MeerKAT project.

	SFB Colloquium
Dr. Sibylle Anderl	ORATED

Grenoble, France

One central question in the context of star formation concerns the evolution of complex chemistry that could eventually trigger the onset of life. In the interstellar medium, complex organic molecules seem to mostly form in reactions happening on the icy surface of dust grains, such that they are released into the gas phase when the dust is heated. The resulting "snow lines", marking regions where ices start to sublimate, play an important role for planet growth and bulk composition in protoplanetary disks. However, they can already be observed in the envelopes of the much younger, low-mass Class 0 protostars that are still in their early phase of heavy accretion. The information on the sublimation regions of different kinds of ices can be used to understand the chemistry of the envelope, its temperature and density structure, and may even hint at the history of the accretion process. Accordingly, it is a crucial piece of information in order to get the full picture of how organic chemistry evolves already at the earliest stages of the formation of sun-like stars. As part of the CALYPSO Large Program (cf. http:/irfu.cea.fr/Projets/Calypso/), we have obtained observations of C18O, N2H+ and CH3OH towards the Class 0 protostar NGC 1333-IRAS4B with the IRAM Plateau de Bure interferometer at sub-arcsecond resolution. We observe an anti-correlation of C18O and N2H+, with N2H+ forming a ring (perturbed by the outflow) around the centrally peaked C18O emission. This reveals the CO snow line in this protostellar envelope with unprecedented resolution, with a radius of ~300 AU. In addition, we observe compact methanol emission, with a radius of ~40 AU. We have modeled the emission using a chemical model coupled with a radiative transfer module, using the temperature and density profiles self-consistently determined by Kristensen et al. (2012). We find that the CO snow line appears further inwards than expected from the binding energy of pure CO ices. This may hint at CO being frozen out in H2O or CO2 dominated ices. Our observations can thereby yield clues on the widely unknown composition of interstellar ices, being the initial seeds of complex organic chemistry.

	Main Colloquium
Prof. Dr. Andreja Gomboc	ORATED

Faculty of Mathematics and Physics, University of Ljubljana, Slovenia

Gamma Ray Bursts (GRBs) are the most violent explosions in the Universe. After a brief period of gamma ray emission, they are followed in longer wavelengths by afterglows, which are observable for hours to weeks. I will review recent results of the international team using the Liverpool Telescope and the LCOGTN to observe GRBs' optical afterglows to study their behaviour in the first minutes to hours after the GRB trigger, thus shedding the light on their physics. Rapid multi-band photometric observations in combination with high-energy data from satellites reveal origin of optical flares occurring contemporaneously with prompt gamma-ray emission and enable statistical studies of GRBs with and without the reverse shock optical emission. However, one of the most important questions of GRB physics is the role of the magnetic field, which can be addressed by measuring linear polarisation of an early optical afterglow. Using the RINGO 2 polarimeter on the Liverpool Telescope we showed in the case of the GRB 120308A that large scale ordered magnetic fields are present in these explosions.

	Lunch Colloquium
Dr. Gabriele Bruni	ORATED

MPIfR

Broad Absorption Line Quasars (BAL QSOs), are objects showing absorption by relativistic outflows (up to 0.2c) in their UV spectra. During the past decade, a considerable observational effort has been done in order to disentangle the two proposed scenarios: the orientation one and the evolutionary one. A fraction of BAL QSOs has a typical GPS/CSS SED. In other cases, a restarting activity seems to be present, resulting in an extended component (tens of Kpc) detected in the MHz range, plus a young component peaking in the GHz range. VLBI observations has shown a complex morphology in some cases, that could confirm this scenario. I will review our latest results about the possible connection between fast outflows and (re)starting radio activity.

	Special Colloquium
Dr. Gunther Witzel	ORATED

UCLA

I report recent observations of Galactic Center sources G2 and Sgr A* from the W. M. Keck Observatory. Both sources are of great interest and vary temporally; G2 is the putative gas cloud now passing through periapse in its orbit around the black hole at the center of the Milky Way Galaxy and Sgr A* is the emission associated with the central black hole. At the time of observation, G2 was expected to have been at closest approach with a separation from Sgr A* of only ~20 mas and, therefore, to be spatially unresolved from Sgr A*. Nevertheless, the two can be disentangled spectrally. We conclude that G2, which recently underwent closest approach, is still intact and compact, in contrast to predictions for a simple gas cloud hypothesis and therefore most likely hosts a central star. The variability of Sgr A* itself has been subject of statistical characterizations in the past. New observations with Spitzer Space Telescope open an unexpected window to timescales unobservable with ground based observatories, and help to assess the question if G2 has changed the variability state of Sgr A*. Furthermore, I will present an outlook on future astrometric measurements at the GC and the methods currently developed to improve adaptive optics supported photometry and astrometry.

	Main Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

X-ray polarimetry promises to give qualitatively new information about high-energy astrophysical sources such as black holes in X-ray binaries, mass accreting supermassive black holes. mass accreting neutron stars, X-ray bright pulsars, magnetars, and gamma-ray bursts. We have developed a scattering polarimeter (X-Calibur) which can be used in the focal plane of a grazing incidence X-ray mirror assembly. X-Calibur combines a low-Z scatterer with an assembly of pixelated Cadmium Zinc Telluride (CZT) detectors to achieve excellent detection efficiency over the broad 20-70 keV energy range. In this talk I will discuss the design and test of the polarimeter and the scientific objectives of two upcoming X-Calibur stratospheric balloon flights (Fall 2016 from Fort Sumner, NM, and 2018/2019 from McMurdo, Ross Island). Furthermore, I will present the results of general relativistic ray tracing studies which we carried through to elucidate the potential of X-ray polarimetric observations with X-Calibur and with a space-borne version of X-Calibur (called PolSTAR) to test the theory of general relativity in the strong gravity regime.

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

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	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

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	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Lunch Colloquium
Dr. Henric Krawczynski	ORATED

Washington University St. Louis / McDonnell Center for the Space Sciences

one more abstract

	Special Colloquium
Dr. Shweta Srivastava	ORATED

Physical Research Laboratory, India

Galaxies containing the signatures of Wolf - Rayet (WR) stars such as a broad HeII 4686 Å emission feature in their optical spectra are known as WR galaxies. The presence of WR stars provides a powerful constraint on the recent star formation in a galaxy. A few galaxies imaged at radio frequencies > 1 GHz reveal a variety of features and spectral shapes. We have started a study of the low radio frequency (< 1 GHz) spectrum and morphology of WR galaxies using the Giant Metrewave Radio Telescope. Our results indicate that the galaxies exhibit a variety of spectral shapes at the low frequencies. We have estimated the synchrotron spectral index alpha to be -0.9 to -0.4 after the separating the thermal free-free emission. We have been able to do a detailed radio continuum study in one of our sample galaxies where the diffuse radio synchrotron emission and compact emission from star forming regions are examined. We find that the detailed morphology of the radio emission resembles the UV emission whereas the overall extent is similar to the NIR emission. I will also talk about combining the radio results with optical IFU which will help us study the spatial correlation between the interstellar medium properties, WR stars and supernova remnants.

	Main Colloquium
Dr. Georgi Dvali	ORATED

LMU and MPI (Munich) and NYU (New York)

We review the framework in which curved gravitational backgrounds, such as black holes and cosmological spaces, are described as composite quantum entities. They are represented as coherent states or Bose-Einstein condensates of constituent soft gravitons at self-sustained quantum critical point. We discuss evidence of these picture and some of its most important theoretical and experimental consequences. In particular, physics underlying the black hole information processing, physics of black hole production in high-energy scattering and some astrophysical and cosmological consequences.

	Special Colloquium
Dr. Carlos Carrasco Gonzalez	ORATED

Centro de Radioastronomia y Astrofisica, CRyA-UNAM, Morelia, Mexico

TBA

	Special Colloquium
Dr. Betsy Mills	ORATED

NRAO

The giant molecular cloud G0.253+0.016 or “The Brick” is a massive (M 105 solar masses) cloud in the Galactic center. Its apparent lack of star formation given its large mass makes it unique in our Galaxy, and as such it has been the subject of more than a dozen papers in just the last 3 years. The properties of this cloud are being used to understand everything from the quiescent initial stages of massive star formation to the overall evolution and orbit of clouds in the entire Galactic center. However, its physical conditions and environment are still poorly constrained. I will present recent VLA observations of this cloud that provide new measurements of its temperature structure and kinematics. The results of these observations also include the detection of an unprecedented number of shock-excited methanol masers, and the first detection of weak, extended continuum emission, apparently due to the external ionization of the cloud. Despite the detection of both masers and continuum emission, we find no new evidence for ongoing star formation in this cloud. However, we do find tantalizing evidence for an overlooked interaction between this cloud and a nearby supernova remnant from the cloud’s morphology, kinematics, and the inhomogeneous distribution of the shock-excited masers. I will conclude with a discussion of how it may be possible to distinguish between scenarios for quiescent and interaction-driven evolution of this and other clouds in the Galactic center.

	Main Colloquium
Dr. Alex Hill	ORATED

Haverford College

The interstellar medium is the intermediary between star formation, stellar feedback, and galaxy evolution. Our understanding of the ISM has evolved from a static three-phase model into one in which turbulence and magnetic fields regulate a much more complex, dynamic medium. I will present magnetohydrodynamic simulations of this turbulent, multi-phase ISM and compare them to Halpha and radio continuum observations.

	Lunch Colloquium
Dr. Miguel Requena Torres	ORATED

MPIfR

TBA

	Main Colloquium
Dr. Yong Shi	ORATED

Nanjing University

Star formation is a key physical process of baryonic matters, and plays crucial roles in driving galaxy formation and evolution. The observed relationship between star formation rates and gas masses, star formation law, offers a powerful empirical way in understanding star formation and is widely invoked in numerical simulations of galaxy formation and evolution. In the past decade, the rich multi-wavelength data of nearby galaxies have enabled well characterizations of this gas-SFR relationship. I will talk about our recent works about star formation law, and show that in addition to the gas density, other factors may also regulate star formation such as existing stars, metallicities etc. This challenges the traditional SFR-gas relationship, implying that different physical mechanisms may play roles in driving star formation during galaxy evolution.

	Lunch Colloquium
Dr. Rusen Lu	ORATED

MPIfR

TBA

	Lunch Colloquium
TBA	ORATED

TBA

	Lunch Colloquium
Dr. Meng Xiang-Grüss	ORATED

MPIfR

Planet formation and evolution has been studied in the past decades with detailed analytical calculations as well as high-resolutional numerical simulations and observations. The observational discovery of exoplanets in the past two decades has provided us with important information about the orbital properties of the planets which led to several significant theoretical improvements. For example, in this context, conditions for planet formation as well as planet-disc interactions have be found. Since the fist discovery of so-called misaligned Hot Jupiters, there has been a complex debate about the origin and evolution of planets on misaligned orbits. In my talk I will present the most promising theories for the formation of misaligned planets and the current attempts to put planet-disc systems into their natural birth environments - the stellar clusters.

	Main Colloquium
Dr. Jamie Farnes	ORATED

Sydney University/CAASTRO

Magnetism is one of the fundamental forces of nature, and the Earth’s magnetic field alone influences the behaviour of numerous animals, and possibly allowed life to have evolved here. Magnetism is important in the development of almost all astrophysical systems, on all scales from planets to the cosmic web. However, we still do not understand how magnetic fields first originated, or how they were amplified to their current strength. Understanding cosmic magnetism requires converting the polarisation properties of extragalactic radio sources into the rest-frame in which the corresponding polarised emission or Faraday rotation is produced. Motivated by this requirement, I present a catalogue of multiwavelength linear polarisation and total intensity radio data for polarised sources from the NRAO VLA Sky Survey (NVSS). Sources were cross-matched with a number of complementary measurements – combining data from major radio polarisation and total intensity surveys such as AT20G, B3-VLA, GB6, NORTH6CM, Texas, and WENSS, together with other polarisation data published over the last 50 years. I present a new technique to cross-match such catalogs, taking into account their fundamentally different resolutions and allowing for estimation of the false-detection rate. For  1000 sources, I present physically-modelled spectral energy distributions (SEDs) in both fractional polarisation and total intensity, containing measurements from 400 MHz to 100 GHz. For a superset of 25,649 sources I provide the total intensity spectral index. This sample shows that objects with steep- versus flat- total intensity spectra have different polarisation SEDs. These two sub-populations suggest the run of polarised fraction with wavelength is predominantly affected by the local source environment, rather than by unrelated foreground magnetoionic material. This has important consequences for the physical interpretation of future broadband polarimetric surveys such as those to be carried out with the Square Kilometre Array (SKA) and its pathfinders and precursors, such as MeerKAT and ASKAP. In addition, the catalogue has also been cross-matched with the Sloan Digital Sky Survey in order to find 599 polarised sources that have a known number of intervening magnesium-absorbing systems. These MgII absorbers are a proxy for normal star-forming galaxies located somewhere along the line of sight. We find the strongest statistical evidence to date that these MgII absorbers are unambiguously associated with higher Faraday rotation. This increase in magnetic field along the line of sight and which is associated with the normal galaxies rules out previously-proposed models of “partial coverage”. Furthermore, the redshift distribution of our sample suggests that magnetic fields have remained essentially constant over the last seven billion years - providing significant implications for dynamo models. I shall briefly discuss the campaign we are now undertaking with the Karl G. Jansky Very Large Array in order to further understand these intervening systems, and how our understanding of cosmic magnetism will be completely revolutionised by next-generation facilities leading up to the SKA.

	Special Colloquium
Dr. Prajval Shastri	ORATED

India

We investigate the systematics of the properties of highly relativistic jets at multiple frequencies, including gamma-ray data from the Fermi telescope and MOJAVE radio imaging on parsec scales. We test the hypothesis that the blazar divide constitutes a dichotomy. We also explore possible measures of the Doppler factor for these highly Doppler-beamed active galactic nuclei.

	Lunch Colloquium
Dr. Jens Kauffmann	ORATED

MPIfR

Star formation in molecular clouds constitutes the foundation for the growth of galaxies and the birth of extrasolar planets. In the last few years several “star formation relations" were developed to quantitatively describe how star formation proceeds in these clouds. For example, these relations form the basis for our understanding of the growth of galaxies in the early universe. Using ALMA and other interferometers we are now examining the Central Molecular Zone of the Milky Way (CMZ; i.e., central  100 pc) as an extreme nearby star formation environment. We find that many star formation relations found to hold near Sun break down in the CMZ. For example, this calls our grasp of the galaxy formation process into question. ALMA and NOEMA now give us a chance to explore our galactic backyard even better as done so far. These instruments also allow us to resolve parsec–scale structure in nearby galaxies. I describe some of the expected discoveries and some of the hurdles we need to overcome on this journey.

	Lunch Colloquium
Dr. Douglas Applegate	ORATED

AIfA

Observations of galaxy clusters not only test the basic parameters of the Lambda-CDM universe, but also test new physics such as non-zero neutrino masses, evolving dark energy, and departures from General Relativity on large scales. In this talk, I will first motivate why clusters are so useful for cosmology and why we are confident that these measurements are robust. In particular, I will describe how gravitational lensing measurements have been essential to recent advances. After showcasing recent results, I will then describe ongoing efforts with the South Pole Telescope Sunyaev Zel’dovich cluster survey that will significantly improve cosmological constraints from clusters in the next few years

	Lunch Colloquium
Dr. Kuo Liu	ORATED

MPIfR

Millisecond pulsars (MSPs) are demonstrated to be nature’s most precise clocks. This feature is attributed to both their regular rotations and stable integrated pulse profiles in radio band. However, recent studies has begun to reveal the irregular nature of their radio signals whose mechanism is unknown. Though MSPs have been mostly studied based on integrated profiles due to their low flux densities, the brightest few of them may still provide enough signal for studies in single-rotation domain. In this talk, I will present an up-to-now overview of investigations into single pulses of MSPs. I will focus on the results from the brightest few sources (J0437-4715, B1937+21, J1713+0747, and J1022+1001), which includes the properties of single pulses and the impact of their variability on timing precision. I will also show that study of single pulses sheds more light on radiation process of MSPs, by e.g. enabling search for coherent emission and distinguishing orthogonal emission modes.

	Special Colloquium
Dr. Dario Colombo	ORATED

University Alberta

TBA

	Lunch Colloquium
Dr. Andrei P. Lobanov	ORATED

MPIfR

TBA

	Special Colloquium
Dr. Pau Amaro-Seoane	ORATED

AEI, Hannover

Observations of the innermost parsec surrounding Sgr A* - the supermassive black hole in the center of our Galaxy - have revealed a diversity of structures whose existence and characteristics apparently defy the fundamental principles of dynamics. I wil review the challenges to the dynamics theories that have been brought forth in the past two decades by the observations of the Galactic Center. I will highlight the role of the recently discovered sub-parsec stellar disk in determining the dynamics and resolving the inconsistencies.

	Lunch Colloquium
Dr. Aritra Basu	ORATED

MPIfR

One of the tightest known correlation in astrophysics, radio–far infrared (FIR) correlation of star-forming galaxies, is primarily driven by star-formation and the interplay between various physical parameters of the interstellar medium (ISM). The redshift evolution of the correlation can shed meaningful insights into cosmic evolution of galaxies. We have studied the radio–FIR correlation in “blue cloud” galaxies chosen from the PRism MUltiobject Survey (PRIMUS) up to redshift (z) of 1.2 in the XMM-LSS field. We employ the technique of image stacking to detect blue star-forming galaxies up to z 1.2, that are otherwise impossible to directly detect with current technology. The stacking analysis allows us to probe the radio–FIR correlation for galaxies that are up to 2 orders of magnitude fainter than the ones detected directly in the FIR bands. The correlation is found to hold good spanning over  5 orders of magnitude in luminosity and widely different galaxy types. For our sample, we find the slope of the correlation to be systematically steeper than unity. The non-linear slope brings to light the ambiguity in using the parameter q[=log(LFIR/Lradio)] as an indicator of evolution of the correlation. Within the uncertainties of our measurement and the limitations of our flux-limited and color-selected sample, we do not find any evolution of the radio–FIR correlation with redshift.

	Main Colloquium
Dr. Harald Schuh	ORATED

Helmholtz-Zentrum Potsdam

The definition and realization of precise and stable reference frames play an important role in modern geodesy, as they are required when we want to monitor changes on the Earth such as plate tectonics or global sea level rise. An overview of the various natural hazards and global change phenomena that can be observed by geodetic techniques will be given. Depending on the spatial scale, various types of measurements can be used, from space geodetic techniques such as GNSS (Global Navigation Satellite Systems), SLR (Satellite Laser Ranging), VLBI (Very Long Baseline Interferometry), and DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite), to local measurements by geodetic surveying instruments. All these techniques are combined in GGOS, the Global Geodetic Observing System of the IAG (International Association of Geodesy), and the concept of this integrative enterprise will be described. Case studies will be presented that document the essential role of precise geodetic data, accurate analysis methods, and realistic mathematical and physical models.

	Lunch Colloquium
TBA	ORATED

TBA

	Main Colloquium
Dr. Christian Fendt	ORATED

MPIA Heidelberg

I will present recent MHD simulations investigating the launching of astrophysical jets. Our simulations treat the time-dependent evolution of the accretion-ejection structure and the subsequent collimation of the disk wind into a high-velocity jet. Our setup considers various approaches for a physical magnetic diffusivity that is essential for loading the accretion material onto the outflow. We find relatively high mass fluxes in the outflow, of the order of 20-40 also consider simulations treating jet launching in a truly bipolar setup, thereby investigating the origin of an intrinsic jet-counter jet asymmetry. Most recent simulations include a mean-field accretion disk dynamo and the launching of outflows by a self-generated disk magnetic field.

	Lunch Colloquium
Dr. Jens Kauffmann	CANCELED

MPIfR

Star formation in molecular clouds constitutes the foundation for the growth of galaxies and the birth of extrasolar planets. In the last few years several “star formation relations" were developed to quantitatively describe how star formation proceeds in these clouds. For example, these relations form the basis for our understanding of the growth of galaxies in the early universe. Using ALMA and other interferometers we are now examining the Central Molecular Zone of the Milky Way (CMZ; i.e., central  100 pc) as an extreme nearby star formation environment. We find that many star formation relations found to hold near Sun break down in the CMZ. For example, this calls our grasp of the galaxy formation process into question. ALMA and NOEMA now give us a chance to explore our galactic backyard even better as done so far. These instruments also allow us to resolve parsec–scale structure in nearby galaxies. I describe some of the expected discoveries and some of the hurdles we need to overcome on this journey.

	Main Colloquium
Dr. Bruce Allen	ORATED

AEI, Hannover

In 1916, Einstein predicted the existence of gravitational radiation, a fundamental consequence of his general theory of relativity. By the end of this decade, we expect to make the first direct observations of gravitational waves, using ground-based instruments (LIGO in the USA, VIRGO in Italy, KAGRA in Japan, LIGO in India). I describe the status and capabilities of the detectors, and discuss the different types of astrophysical sources which we hope to detect. We expect that the first direct detections of gravitational waves (perhaps as early as 2017) will be from the coalescence and merger of binary neutron star pairs. Such events may also be accompanied by electromagnetic signals (gamma-ray, optical and radio). I’ll also talk about the longer-term perspectives, and describe how some of the new data analysis methods and technology developed for the gravitational wave search have benefited more conventional electromagnetic astronomy. For example in the past four years the volunteer distributed computing project Einstein@Home has discovered over fifty new radio and gamma-ray pulsars.

	Lunch Colloquium
Dr. Michael Lam	ORATED

MPIfR

TBA

	Special Colloquium
Dr. Yasuyuki Tanaka	ORATED

Hiroshima University

Since the successful launch of Fermi Gamma-ray Space Telescope in 2008, the Large Area Telescope (LAT) onboard Fermi has been monitoring the MeV/GeV gamma-ray sky. Thanks to the large field-of-view (2.4 str), Fermi-LAT scans the all-sky every 3 hours and can detect flaring blazars from all sky. This allows to trigger multi-wavelength follow-up observation for the flaring blazar. In this talk, I present Fermi-LAT and multi-wavelength results of (1) TeV-emitting Flat Spectrum Radio Quasar 4C 21.35 (Tanaka et al. 2011), extremely hard TeV blazar (so-called extreme blazar) 1ES 0347-121 (Tanaka et al. 2014), and (3) Broad Line Radio Galaxy 3C 120 (Tanaka et al. 2015). We also performed optical polarimetric follow-up observations for flaring Fermi blazars using Kanata telescope, and highlights of Kanata results are presented (e.g., Itoh et al. 2013). Based on these results, we discuss the location of gamma-ray emission region, gamma-ray emission mechanism, energetics and magnetic field structure of AGN jets. New international X-ray satellite Astro-H (Takahashi et al. 2012) is scheduled to be launched this year. New instrument HONIR (Hiroshima optical and near-infrared camera) was attached to Kanata telescope in 2014, and optical and near-infrared simultaneous polarimetric observation is now feasible (Akitaya et al. 2014). We also discuss how these new instruments will provide new insights into AGN jet physics.

	Main Colloquium
Dr. Fabio Zandanel	ORATED

GRAPPA Institute, University of Amsterdam

I will briefly review the current picture of cosmic rays in clusters of galaxies. Cosmic-ray protons are confined in galaxy clusters and can accumulate there for cosmological times. Hadronic interactions of cosmic rays with the cluster ambient gas generate secondary electrons, gamma-rays and neutrinos possibly resulting in non-thermal emission from radio to ultra-high energies. Are we detecting these secondaries? Will we ever detect them? I will present my work aiming to answer these question.

	Main Colloquium
Dr. Craig Heinke	ORATED

University of Alberta

The thermal radiation from the surfaces of neutron stars can inform us about their interior physics. The cooling of neutron stars, which is dominated by neutrino emission from the neutron star’s core, tells us about the nature and interactions of the particles in the core. A subject of particular interest is superfluidity — a quantum state of certain fluids allowing frictionless flow, identified on Earth only in two isotopes of helium at extremely low temperatures. Both protons and neutrons inside neutron stars are thought to become superfluid, but the properties of this superfluid are hard to study. The supernova remnant Cassiopeia A contains the youngest ( 330 years) known neutron star, which can strongly constrain cooling models. We recently found evidence that it is cooling rapidly, leading to the interpretation that the neutrons in the Cas A neutron star are currently undergoing a superfluid phase transition. If so, this constrains the interactions of matter at very high densities, and the nature of neutron stars.

	Lunch Colloquium
Ana Mikler	ORATED

AIfA

We study the galaxy clustering properties of the AKARI Deep Field South (ADFS), between redshifts 0 and 3, using the Herschel Multi-tiered Extragalactic Survey, HerMES. The data were taken by the SPIRE instrument at 250 um, and these infrared observations allow us to obtain information on the star-formation properties and the dust content of the galaxies. We obtain the angular separation and estimate the angular correlation function, to ultimately constrain the spatial correlation length. The ADFS region has been poorly studied until now, and our clustering analysis moves us one step further in the understanding of the cosmological environment and the density field of the galaxies in it. Our work shows that the clustering properties of the high-redshift galaxies selected at long wavelengths to be not substantially different from objects selected with completely different methods, like for example optical selection.

	Special Colloquium
Dr. Daniel Seifried	ORATED

University of Cologne

Turbulence was shown to overcome the longstanding problem of catastrophic magnetic braking which prevents the formation of early type Class 0 stage protostellar disks. I will present numerical simulations of protostellar disk formation investigating its impact on the formation of disks. Turbulence allows Keplerian disks to form at an early stage already and leads to a highly anisotropic and episodic accretion flow through a few, very narrow accretion channels. This is in strong contrast to a non-turbulent environment, where accretion is much more well ordered. I will show how such an anisotropic accretion flow naturally leads to the formation of rotationally supported, Class 0 stage protostellar disks and how it affects the magnetic field structure. Finally I give some examples how such simulated protostellar disks and outflows appear in synthetic observations, e.g. with ALMA.

	Special Colloquium
Dr. Cormac Purcell	ORATED

Sydney

The Gum Nebula is 36 degree wide shell-like emission nebula at a distance of only 450 pc. It has been hypothesised to be an old supernova remnant, fossil HII region, wind-blown bubble, or combination of multiple objects. Here we investigate the magneto-ionic properties of the nebula and its impact on the ISM using data from recent surveys: radio-continuum data from the NRAO VLA and S-band Parkes All Sky Surveys, and H-alpha data from the Southern H-Alpha Sky Survey Atlas. By analysing rotation measures through the nebula and by fitting a simple model, we are able to measure the geometry and strength of the local ordered magnetic field. The fitted compression factor at the edge of the nebula strongly constrains its likely origin for the first time. The nebula is also useful as a probe of the magnetic field on parsec scales and the fitted value of local magnetic pitch-angle represents a significant deviation from the median orientation on kiloparsec scales. I discuss the implications for Galactic structure and plans for expanded analysis in the era of the SKA.

	Lunch Colloquium
Dr. Olaf Wucknitz	ORATED

MPIfR

Temporal scatter-broadening can seriously affect our ability to find pulsars orbiting the central mass in our Galaxy. Many of these invaluable probes of geometry around the black hole are expected, but none have been found in close orbits so far, possibly as result of strong scattering. The magnetar PSR J1745-2900 discovered in 2013 at a separation of < 3 arcsec is not the optimal type of pulsar for studies of general relativity, but it can be used to investigate the scattering properties so that search strategies can be adapted accordingly. In this talk I present an observation of PSR J1745-2900 using short baselines between VLBI stations in Europe in a non-standard interferometry mode. The most important goal is determining the distance of the scattering screen, or the distribution of scattering material if not confined to one screen. The analysis is based on phase-binned visibilities that allow measuring the shape of the scattering disk and how it grows with increasing delay over the scattering tail of the pulse profile. Narrow rings growing with the square root of delay are expected for a single thin scattering screen and the preliminary results are indeed consistent with this expectation. This means that most of the angular and temporal broadening is caused by the same and relatively thin scattering screen and that, in contrast to standard models of the interstellar scattering behaviour near the Galactic centre, this screen is located about halfway between the centre and us.