Main Colloquium
Dr. Pierre Ferruit	ORATED

European Space Agency (ESA)

The James Webb Space Telescope (JWST), scheduled for launch in October 2018, will be one of the great observatories of the next decade. JWST and its suite of 4 instruments will provide imaging, spectroscopic and coronagraphic capabilities over the 0.6 to 28.5 micron wavelength range and will offer an unprecedented combination of sensitivity and spatial resolution to study targets ranging from our Solar System to the most distant galaxies. In this presentation, I will first present the latest status of the mission and give an overview of its capabilities. I will then give details on the scientific timeline and in particular of the on-going general observer (GO) call. Last I will give an overview of the contents of the guaranteed time and early-release science programs that have been announced in 2017.

	Special Colloquium
Dr. Gunther Witzel	ORATED

UCLA, USA

I report recent observations of the Galactic Center sources G1, G2, and Sgr A* from the W. M. Keck Observatory, the VLT, and Spitzer Space Telescope. All three sources vary temporally and are in the focus of numerous recent studies; G2 is the putative gas cloud that 3 years ago passed through periapsis in its orbit around the black hole at the center of the Milky Way, and Sgr A* is the emission associated with Sgr A*’s accretion. In 2014, G2 was observed at closest approach with a separation from Sgr A* of only ~20 mas and has been spatially unresolved from Sgr A* since then. Nevertheless, the two can be disentangled spectrally. We conclude that G2, more than 3 years after periapse, is still intact and compact in the continuum. This is in contrast to predictions for a simple gas cloud hypothesis, and therefore G2 most likely hosts a central star. Similar arguments can be made for the nature of G1, and I will discuss the relation between the two objects. 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 or G1 have changed the variability state of Sgr A*. I will present the recent status of our variability studies (from Space and with Keck and VLT) that shed some light on the accretion processes onto the closest supermassive black hole. 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. Pierre Hily-Blant	CANCELED

UGA/IUF/IPAG, Grenoble

To which extent did the primitive solar system keep memory of its interstellar past is a key question from planetary science and astrophysics perspectives. Related to it, the total amount of volatile carbon, oxygen, and nitrogen, and their spatial distribution, in the early protosolar nebula (PSN), and in PSN analogs, is a fascinating issue in our understanding of the chemical composition of exoplanets. In this talk, while presenting these questions from an astrochemical point of view, I will focus on one element namely, nitrogen. Our starting point for the history of nitrogen in the solar system will be comets for which all observations converge towards a single value of the 14N/15N isotopic ratio of ~140. This represents a threefold 15N-enrichment with respect to the elemental 14N/15N ratio of 441 in the PSN. Basically three explanations can be advanced for the discrepancy: 1/ cometary carriers of the primary reservoir of nitrogen so far escaped detection, or fractionation, taking place in 2/ cometary nuclei over the last 4.6 Gyr, 3/ in the PSN, or 4/ in the interstellar cloud where the Sun formed. I will review the existing measurements in interstellar clouds and in protosolar nebula analogs. In particular, I will present the direct measurement of the 14N/15N ratio in the disk orbiting TW Hya performed with ALMA, which demonstrates that fractionation is present already at the PSN stage. Put into a galactic context, the measured ratio of 323+/-30 is interpreted as the elemental isotopic ratio of nitrogen in the present-day solar neighbourhood. I will also present the recent direct determination of the HCN/HC15N in the L1498 prestellar core, suggesting that nitrogen fractionation is not efficient in such a cold environement. However, source to source variations cannot be excluded, while chemical models remain questionable. Future perspectives in the field will close the talk.

	Special Colloquium
Dr. Tomasz Kamiński	ORATED

Harvard-Smithsonian Center for Astrophysics, MA, USA

CK Vul erupted in 1670-72 and is considered one of the oldest nova-like objects known to astrophysics. The observational characteristics of the object, known from ancient records of the outburst and modern studies of the remnant, rule out a classical-nova scenario for the 17th century eruption. It was most likely one of rare objects which we know today as "red novae" or "intermediate-luminosity optical transients". They erupt in a stellar-merger event. I am going to present (sub-)millimeter-wave observation of CK Vul, including ALMA data, which reveal the remnant of CK Vul is rich in molecular gas and dust. The molecular gas has very peculiar isotopic composition which supports the merger hypothesis for CK Vul's outburst and provides information about the progenitor binary system which collided 348 yr ago. In particular, I am going to show observations of the radioactive nuclide of 26Al, whose observation gives us a glimpse into the collision processes and have important implications for the 26Al production on the Galactic scale.

	Informal Colloquium
Multiple Speakers: Check abstract for details	ORATED

The MPI für Radioastronomie in Bonn and the Astro Space Centre of the P.N. Lebedev Physical Institute of the Russian Academy of Sciences are collaborating in the framework of a Humboldt Partnership Program, with the main focus of the collaboration laid on the space VLBI mission "RadioAstron". Marking the the second year of the Program, a workshop will take place in Bonn on December 13-15. The workshop will also embrace a number of external collaborators of the Program, with participants from Instituto de Astrofísica de Andalucía, Aalto University, and the Istituto di Planetologia e Astrofísica Speziali expected to take part. See the meeting webpage at https://events.mpifr-bonn.mpg.de/indico/event/61/ The first day of the workshop (December 13) will be open for general public, featuring presentations about key science projects of the RadioAstron and their potential synergies with the GMVA and EHT observations. The speakers and topics in Session IV (see https://goo.gl/hSx2uW) are: Matt Lister: Jet studies with the MOJAVE program Antonio Fuentes: Total and linearly polarized synchrotron emission from overpressured magnetized relativistic jets Alexander Pushkarev: Shapes and opening angles of AGN jets Alexander Plavin: Core-shift measurements in a large sample of AGNs and their implications for astrophysics and astrometry Silke Britzen: M87: Turbulent loading leading to large-scale episodic wiggling Jun Liu: Effelsberg monitoring in support of RadioAstron observations of high Tb blazars

	Informal Colloquium
Multiple Speakers: Check abstract for details	ORATED

The MPI für Radioastronomie in Bonn and the Astro Space Centre of the P.N. Lebedev Physical Institute of the Russian Academy of Sciences are collaborating in the framework of a Humboldt Partnership Program, with the main focus of the collaboration laid on the space VLBI mission "RadioAstron". Marking the the second year of the Program, a workshop will take place in Bonn on December 13-15. The workshop will also embrace a number of external collaborators of the Program, with participants from Instituto de Astrofísica de Andalucía, Aalto University, and the Istituto di Planetologia e Astrofísica Speziali expected to take part. See the meeting webpage at https://events.mpifr-bonn.mpg.de/indico/event/61/ The first day of the workshop (December 13) will be open for general public, featuring presentations about key science projects of the RadioAstron and their potential synergies with the GMVA and EHT observations. The speakers and topics in Session III (see https://goo.gl/obmwVf) are: Mihkail Lisakov: Complex nature of the apparent core in 3C 273 Jae-Young Kim: Spatially resolved origin of mm-wave linear polarization in the nuclear region of 3C 84 Sergey Pilipenko: The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering Efthalia Traianou: Looking into the heart of the gamma-ray loud TXS 2013+370 blazar

	Lunch Colloquium
Dr. habil. Yuri Y. Kovalev	ORATED

ASC Lebedev

In this talk I will present the current status of the Space VLBI mission as well as recent results of RadioAstron studies of AGNs, pulsars, masers, interstellar medium as well as gravitational redshift experiment

	Informal Colloquium
Multiple Speakers: Check abstract for details	ORATED

The MPI für Radioastronomie in Bonn and the Astro Space Centre of the P.N. Lebedev Physical Institute of the Russian Academy of Sciences are collaborating in the framework of a Humboldt Partnership Program, with the main focus of the collaboration laid on the space VLBI mission "RadioAstron". Marking the the second year of the Program, a workshop will take place in Bonn on December 13-15. The workshop will also embrace a number of external collaborators of the Program, with participants from Instituto de Astrofísica de Andalucía, Aalto University, and the Istituto di Planetologia e Astrofísica Speziali expected to take part. See the meeting webpage at https://events.mpifr-bonn.mpg.de/indico/event/61/ The first day of the workshop (December 13) will be open for general public, featuring presentations about key science projects of the RadioAstron and their potential synergies with the GMVA and EHT observations. The speakers and topics in Session II (see https://goo.gl/7ghqLZ) are: José L. Gómez: AGN Polarization Key Science Program: Highlights Evgeniya V. Kravchenko: The first results on S5 0716+714 imaging with RadioAstron Gabriele Bruni: Results from the RadioAstron AGN polarization KSP: observations of 3C 273 at minimum activity

	Informal Colloquium
Multiple Speakers: Check abstract for details	ORATED

The MPI für Radioastronomie in Bonn and the Astro Space Centre of the P.N. Lebedev Physical Institute of the Russian Academy of Sciences are collaborating in the framework of a Humboldt Partnership Program, with the main focus of the collaboration laid on the space VLBI mission "RadioAstron". Marking the the second year of the Program, a workshop will take place in Bonn on December 13-15. The workshop will also embrace a number of external collaborators of the Program, with participants from Instituto de Astrofísica de Andalucía, Aalto University, and the Istituto di Planetologia e Astrofísica Speziali expected to take part. See the meeting webpage at https://events.mpifr-bonn.mpg.de/indico/event/61/ The first day of the workshop (December 13) will be open for general public, featuring presentations about key science projects of the RadioAstron and their potential synergies with the GMVA and EHT observations. The speakers and title of the talks of Session I (see https://goo.gl/TxTcdX) are: Yuri Kovalev: RadioAstron AGN survey Tuomas Savolainen: Results from RadioAstron Nearby AGN Key Science Program Laura Vega García: Strong AGN Key Science Program

	Special Colloquium
Dr. Sebastian Kiehlmann	ORATED

Caltech

The Owens Valley Radio Observatory (OVRO) runs a variety of radio telescopes in the frequency range from ~10 MHz to ~100 GHz. These instruments are dedicated to a range of science cases in observational cosmology - Galactic foreground emission, Epoch of Galaxy Assembly, Epoch of Reionization - and time domain astronomy - extrasolar planets, novae, X-ray binaries/microquasars, blazars, and fast radio bursts. I will give a brief overview over the six current and future projects at OVRO: C-BASS, COMAP, OVRO-LWA, DSA-10, 40 m Monitoring Program, and SPRITE.

	Special Colloquium
Dr. Laura M. Fissel	ORATED

NRAO, Charlottesville

The extent to which magnetic fields influence the formation and evolution of molecular clouds remains a key open question in our understanding of the star formation process. Maps of polarized thermal dust emission can be used to create detailed portraits of magnetic field morphology, yet observing through the Earth's atmosphere has typically restricted polarimeters to maps of small areas or extremely bright clouds. In this talk I will discuss results from a survey of the young giant molecular cloud Vela C with the Balloon-borne Large Aperture Sub-mm Telescope for Polarimetry (BLASTPol). By applying the statistical analysis techniques to both BLASTPol data and synthetic observations of MHD cloud formation models we find that the magnetic field of Vela C is likely significantly inclined with respect to the plane-of-the-sky. Comparisons between magnetic field orientation traced by BLASTPol and elongation of column density and molecular line map structures also indicate that the large-scale magnetic field of Vela C is strong enough to influence the cloud gas dynamics. With upcoming instrumentation such as the next-generation BLAST polarimeter and the TolTEC polarimeter we will soon be able to apply the same analysis techniques to dozens of clouds at even higher resolution, providing important constraints on the role of magnetic fields in star and planet formation.

	Main Colloquium
Prof. Anna Watts	ORATED

Astronomical Institute Anton Pannekoek, University of Amsterdam

Densities in neutron star cores can reach up to ten times the density of a normal atomic nucleus, and the stabilising effect of gravitational confinement permits long-timescale weak interactions. This generates matter that is neutron-rich, and opens up the possibility of stable states of strange matter, something that can only exist in neutron stars. Our uncertainty about the nature of matter under these conditions is encoded in the Equation of State, which can be linked to macroscopic observables like mass, radius, tidal deformation or moment of inertia. Measuring the EOS of matter in the cores of neutron stars is, for this reason, that dreaded thing - a Holy Grail of Astrophysics - as measured by the standard unit of mentions in grant applications. One very promising technique for measuring the EOS exploits hotspots (burst oscillations) that form on the neutron star surface when material accreted from a companion star undergoes a thermonuclear explosion (a Type-I X-ray burst). As the star rotates, the hotspot gives rise to a pulsation. Relativistic effects then encode information about the EOS into the pulse profile. However the mechanism that generates burst oscillations remains unknown, 20 years after their discovery. Ignition conditions, flame spread, and the magnetohydrodynamics of the star’s ocean all play a role. I will review the progress that we are making towards cracking this long-standing problem, and establishing burst oscillations as a tool par excellence for probing dense matter. This is a major goal for future large area X-ray telescopes such as eXTP and STROBE-X.

	Informal Colloquium
Hiep Nguyen	ORATED

Department of Physics and Astronomy, Macquarie University, Sydney

Many studies have proved the existence of the dark interstellar medium (Dark ISM) which is not detected by traditional radio emission from atomic hydrogen (HI) and carbon monoxide (CO) molecules. To probe this gas component, interstellar dust has often been used as a proxy for total gas column density N_H. By comparing the thermal dust data from Planck satellite (Release 1.2) and the Pan-STARRS with accurate (opacity-corrected) HI column densities and newly-published OH data from the Arecibo Millennium survey and 21-SPONGE, we confirm tight linear correlations between dust optical depth, dust radiance, reddening E(B−V) and the total proton column density N_H in the range ~0.1–2.7e21 cm−2, along sightlines with no molecular gas detections. We derive a ratio N_H/E(B−V) of ~7.9e21 cm−2 mag-1 for purely atomic sightlines at |b|>10 deg, consistent with Liszt (2014). Based on our own measurements of dust opacity and dust specific luminosity, we argue that while the variation of opacity reported by Planck Collaboration (2014) is largely due to the evolution of dust grains in the ISM, the change in their specific luminosity may come from the presence of dark gas. We estimate the molecular hydrogen column densities N_H2 from these linear relationships and hence derive the OH/H2 abundance ratio X_OH for all molecular sightlines. The X_OH ratios derived from the three N_H proxies are basically consistent with mean value around ~1e−7. Our results show no evidence of systematic trends in OH abundance with N_H2 in the range N_H2 ~ 0.1–10e21 cm−2 suggesting that OH may be used as a reliable proxy for H2 in this range, which includes sightlines with both CO-dark and CO-bright gas.

	Special Colloquium
Dr. Andrey Sobolev	ORATED

Kourovka Astronomical Observatory, Ural Federal University, Ekaterinburg, Russia

We present the first VLBI observations of structure of water maser made with a very long base line interferometric array involving the RadioAstron earth-orbiting satellite station as one of its elements. We observed the masers in the star-forming region Cepheus A. We detected six distinct components with an unprecedented baseline of 3.3 Earth diameters, which gave a fringe spacing of 66 micro-arcseconds. We examined the profile of the 0.6 km s−1 feature in detail. In total power, it appears as a single Gaussian component of strength 580 Jy and width of 0.7 km s−1. There is no difference in the profiles in right and left circular polarization, implying the longitudinal magnetic field component is weaker than 120 mG. The cross power spectrum shows two unresolved components smaller than 15 micro-arcsec separated by 0.5 km s−1 in velocity and separated by 25 micro-arcsec. The diameters of the components (15 micro-arcsec) correspond to a linear scale of 1.6e11 cm, about the diameter of the Sun. This is the smallest structure ever observed in a Galactic maser. The expected interstellar broadening along the path to Cepheus A is about 7 micro-arcsec, which may have a small effect on the angular size determination. These masers appear to be associated with the compact HII region HW3diii. The brightness temperatures are greater than about 1e15 K, and the line widths are 0.5 km s−1, characteristic of a kinetic temperature of about 100 K. The components detected are likely to represent turbulent eddies in the maser medium. This appears to be the first observation with resolution of the scale at which turbulence is dissipating.

	Main Colloquium
Prof. Alex de Koter	ORATED

Sterrenkundig Instituut Anton Pannekoek, Universiteit van Amsterdam

Massive stars may have been the first sources of light after the Big Bang. They are potential contributors to the re-ionization of the Universe and have likely played a crucial role in galaxy formation. The most massive stars today easily outshine the sun by a factor of a million or more, hence provide strong radiative feedback on their host environment. Through powerful stellar winds and supernova ejecta they enrich their surroundings with newly processed chemical elements, which constitute the building block of terrestrial planets and life. Indeed, if not for massive stars, we would not exist. In this talk I will first sketch the role of massive stars in the grand scheme of things. Then, I will focus on aspects of the outcome of the formation of the most massive stars, including maximum formation mass, initial mass function and multiplicity properties. Finally, I will present a possible new insight into the formation mechanism of massive close binaries.

	Special Colloquium
Dr. Dominique Eckert	ORATED

Max-Planck-Institute for Extraterrestrial Physics

The properties of the intracluster medium can be traced both by X-ray observations and measurements of the Sunyaev-Zel'dovich signal. The two techniques provide highly complementary information on the distribution and thermodynamic properties of the hot intracluster medium, and both of them are tightly correlated with cluster mass. I will describe how the two probes can be exploited jointly to set tight constraints on ICM properties out to the virial radius of local clusters. Based on some pilot studies with archival ROSAT data, in 2014 we obtained a very large program on XMM-Newton to follow up the most significant Planck clusters in the redshift range 0.04-0.1. I will present preliminary results of this program, focusing on thermodynamic properties, mass profiles, gas mass fraction, and non-thermal pressure support.

	Special Colloquium
Dr. Andrey Sobolev	CANCELED

Kourovka Astronomical Observatory, Ural Federal University, Ekaterinburg, Russia

We present the first VLBI observations of structure of water maser made with a very long base line interferometric array involving the RadioAstron earth-orbiting satellite station as one of its elements. We observed the masers in the star-forming region Cepheus A. We detected six distinct components with an unprecedented baseline of 3.3 Earth diameters, which gave a fringe spacing of 66 micro-arcseconds ($\mu$as). We examined the profile of the 0.6 km s−1 feature in detail. In total power, it appears as a single Gaussian component of strength 580 Jy and width of 0.7 km s−1. There is no difference in the profiles in right and left circular polarization, implying the longitudinal magnetic field component is weaker than 120 mG. The cross power spectrum shows two unresolved components smaller than 15 $\mu$as separated by 0.5 km s−1 in velocity and separated by 25 $\mu$as. The diameters of the components (15 $\mu$as) correspond to a linear scale of 1.6e11 cm, about the diameter of the Sun. This is the smallest structure ever observed in a Galactic maser. The expected interstellar broadening along the path to Cepheus A is about 7 $\mu$as, which may have a small effect on the angular size determination. These masers appear to be associated with the compact HII region HW3diii. The brightness temperatures are greater than about 1e15 K, and the line widths are 0.5 km s−1, characteristic of a kinetic temperature of about 100 K. The components detected are likely to represent turbulent eddies in the maser medium. This appears to be the first observation with resolution of the scale at which turbulence is dissipating.

	Main Colloquium
Prof. Hans-Walter Rix	CANCELED

MPIA, Heidelberg

TBD

	Lunch Colloquium
Dr. Christian Henkel	ORATED

MPIfR

The determination of extragalactic CNO-S-Si isotope ratios requires observations with extreme sensitivity. As a consequence of limited signal-to-noise ratios and isotope ratios often exceeding an order of magnitude, very little could been done so far. However, this is now rapidly changing, thanks to the construction of ALMA and the expansion of the Plateau de Bure Interferometer into NOEMA. This talk provides a brief summary of extragalactic work so far done on CNO-S-Si isotope ratios, briefly mentioning the main underlying processes of nucleosynthesis. Also introduced are cases, where fractionation can be neglected, and others, where fractionation might influence the resulting ratios in a truly drastic way.

	Main Colloquium
Oliver Müller	ORATED

Departement Physik, Universität Basel

Dwarf galaxies are tracers of the fine-structure of the large-scale structure of the universe, but their predicted abundance and distribution from simulations is in serious conflict with observations in the Local Group, today's best studied group of galaxies. Recently, two planes of satellites were discovered around Cen A, providing a unique opportunity to test cosmological predictions beyond the Local Group. We surveyed the complete Centaurus Group with the Dark Energy Camera, doubling the census of dwarf galaxies in the group. We found evidence that these satellite planes are corotating, posing a major challenge to Lambda+CDM. Comparison to high-resolution dark matter simulations show that this finding is highly significant. I will connect this to the recently established and unexpected relation between the number of dwarf galaxies and the size of the bulge of the host galaxy in the context of Lambda+CDM cosmology and MOND.

	Lunch Colloquium
Dr. Jörg Dabringhausen	ORATED

Astronomical Institute, Charles University, Prague, Czech Republic

Assuming virial equlibrium and Newtonian dynamics, the observed velocity dispersions of early-type galaxies (ETGs) are usually larger than the predictions for their velocity dispersions based on the amount of baryonic matter they contain. This descrepancy is particularly large at the faint end of the luminosity function of ETGs. The conventional interpretation of this finding is that ETGs contain non-baryonic matter, and that the faintest ETGs consist almost exclusively of this exotic type of matter. Using an extensive catalogue of ETGs and simple analytic approximations concerning the stellar populations and the law of gravity, I will discuss how the internal dynamics of ETGs can also be understood from their baryonic content alone.

	Main Colloquium
Dr. Fabian Walter	ORATED

MPIA, Heidelberg

A prime objective of observational astrophysics is to characterize the earliest sources in the first Gyr of the universe, and to peer into the cosmic times when the first stars, black holes and galaxies formed. Although galaxy candidates are now identified up to redshifts of about 10, their faintness typically precludes detailed studies of their nature. Quasars, on the other hand, are the most luminous non-transient sources known and can be studied in detail at the earliest cosmic epochs. The discovery and characterization of a statistically significant sample of quasars at z>6 is crucial to study the epoch of reionization. I will present our progress in building such a statistical sample, which led to tripling the number of these quasars in just the last three years. I will discuss the diverse range of physical properties of this quasar sample as well as our follow-up studies from optical to radio wavelengths, including a new quasar at a record redshift (z=7.5). In particular, recent observations with ALMA revealed the presence of far-infrared companions around the quasars, and provide key constraints on the spatially resolved properties of the quasar host galaxies. Through multi-line ALMA spectroscopy we can also derive first constraints on the physical conditions of the interstellar medium in the quasar hosts. I will also discuss the potential of future JWST observations.

	Special Colloquium
Dr. Masaki Yamaguchi	ORATED

Institute of Astronomy, School of Science, University of Tokyo

We develop a method for identifying a compact object in binary systems with astrometric measurements and apply it to gamma-ray binaries. Compact objects in five gamma-ray binaries are unknown (either a neutron star or a black hole), which is responsible for the fact that emission mechanisms in such systems have not yet been confirmed. The accurate estimate of the mass of the compact object allows us to identify the compact object in such systems. Astrometric measurements are expected to enable us to estimate the masses of the compact objects in the binary systems via a determination of a binary orbit. We calculate the probability that the compact object in gamma-ray binaries are correctly identified (= confidence level) for given masses of the compact object and for given precisions of an astrometric mission. From the resultant confidence levels, we conclude that for two gamma-ray binaries, we can identify the compact object at high confidence level (even > 99%) with 10-microarcsecond level astrometry, such as Gaia and JASMINE.

	Special Colloquium
Prof. Yashwant Gupta	ORATED

National Centre for Radio Astrophysics, India

The Giant Metrewave Radio Telescope (GMRT) is today a major international Radio Astronomy facility working in five discrete bands in the frequency range of 150 MHz to 1500 MHz, with a maximum instantaneous bandwidth of 32 MHz. Consisting of 30 fully steerable antennas of 45 metre diameter each, it can be used as an aperture-synthesis array for imaging, as well as a phased array to study compact radio sources such as pulsars. The GMRT has produced several important results in the past 15 years of operations -- a few select ones will be highlighted. The GMRT is undergoing a major upgrade that will improve its sensitivity by a factor of upto three and make it a much more versatile instrument. The goal is to have seamless frequency coverage from about 100 to 1500 MHz, with a maximum instantaneous bandwidth of 400 MHz; improved receiver systems with higher G/Tsys; versatile digital back-end correlator and pulsar receiver using the latest FPGA and GPU technologies; revamped servo system; sophisticated monitor and control system; and matching improvements in infrastructure and computing. This upgrade will keep the GMRT at the forefront as one of the most sensitive facility in the 100 to 1500 MHz range, till the SKA phase I comes along. Most of the sub-systems of the upgraded GMRT (uGMRT) are nearing completion and delivery, and the upgraded observatory is being made available to users in a phased manner, from April 2016 onwards, and the full uGMRT is expected to be released by early 2018. An overview of the upgrade activities, their current status and future plans, including specific challenges faced, will be described. First science results from the uGMRT and future potential will also be presented.

	SFB Colloquium
Prof. Sebastiano Cantalupo	ORATED

ETH Zürich

Gravitational collapse during the Universe's first billion years transformed a nearly homogeneous matter distribution into a network of filaments - the Cosmic Web - where galaxies form and evolve. Because most of this material is too diffuse to form stars, its study has been limited so far to absorption probes against background sources. In this talk, I will present the results of a new program to directly detect and study high-redshift cosmic gas in emission using bright quasars and galaxies as external "sources of illumination". In particular, I will show results from ultra-deep narrow-band imaging and recent integral-field-spectroscopy as a part of the MUSE Guaranteed Time of Observation program that revealed numerous giant Lyman-alpha emitting filaments extending up to several hundred kpc around quasars and bright galaxies. I will discuss how the unexpectedly high luminosities of these systems, together with the constraints from Helium and metal extended emission, represent a challenge for our current understanding of cosmological structure formation. In particular, I will show that current observations suggest that a large amount of "cold" and dense gaseous "clumps" should be present around high-redshift galaxies and I will present our first attempts to understand the origin and nature of these structures using high-resolution hydrodynamical simulations.

	Main Colloquium
Prof. Klaus Desch	ORATED

University of Bonn, Physikalisches Institut

Physics beyond the Standard Model may hide at very low energies. The axion, postulated by Wilczek and Weinberg almost 40 years ago, is a very light, very weakly interacting new particle which, if it exists, could answer a long-standing question of fundamental physics: why is the electric dipole moment of the neutron so unnaturally small? Moreover, axions may be (all or part of) the dark matter in our universe. Axions may be copiously produced in our sun. The proposed IAXO experiment will be more than 10000 times more sensitive to these particles than the previous leading experiment, CAST at CERN. In the talk, I will motivate solar and other axion searches and will present the current planning of IAXO which brings together technologies from particle physics, astrophysics and accelerator physics. I will also discuss a potential step-wise realisation of IAXO.

	Lunch Colloquium
Priv.-Doz Rainer Mauersberger	ORATED

MPIfR

I will review the paper with this title, see the paper with the same title by Katia Levecque et al. in Reserch Policy, 46, 868 (2017) at https://doi.org/10.1016/j.respol.2017.02.008

	Special Colloquium
Dr. Paul Ho	ORATED

East Asian Observatory and ASIAA

The East Asian Observatory (EAO) was established in 2014, and incorporated in Hawaii. The EAO is formed by the four core observatories in East Asia: NAOC, NAOJ, KASI, and ASIAA. The goal is to build world class facilities by combining the resources from the East Asian regions. The first task for the EAO has been to take over the operations of the James Clerk Maxwell Telescope from the UK community. In this talk, I will describe the activities of JCMT and EAO over the last two years, as well as our future aspirations. I will also describe some of the new science capabilities at the EAO/JCMT.

	Main Colloquium
Dr. Sylvain Bontemps	ORATED

Laboratoire d'Astrophysique de Bordeaux, CNRS, Université de Bordeaux

While the origin of stellar masses for solar type stars appear to nicely fit with a simple Jeans fragmentation in the typical dense cold gas of nearby molecular clouds, higher masses of OB type stars have a much less clear origin. This often leads researchers to propose that high-mass stars may not form the same way than low-mass stars. This is not so clearly the case, high-mass stars may very well form exactly like low-mass stars through a direct monolithic collapse. In this case, one has to understand how molecular cloud fragmentation can indeed produce Jeans instable cores with masses much larger than the typically observed thermal Jeans masses. I will show that the most recent observations with millimeter interferometers clearly point to monolithic collapses and that the present quest is therefore to reveal the origin of apparently "super-Jeans" cores in molecular clouds. Since high-mass stars are the trademarks of clustered star formation, and since most stars form in clusters, this issue of the origin of high stellar masses has important implications for the whole evolution of galaxies.

	Master Colloquium
Tomas Alberto Cassanelli	ORATED

MPIfR

The out-of-focus (OOF) holography technique allows users to obtain low resolution maps of the wavefront (aberration) distribution in an antenna surface using astronomical observations. It requires ---in contrast to traditional holography measurements--- only one in-focus and two out-of-focus images of a compact source at a good signal-to-noise ratio. The 100-m Effelsberg antenna has an active sub-reflector surface with 96 actuators which are set in order to correct the gravitationally-caused surface deformations of the primary dish. The active surface is controlled via a static look-up table, which was calculated from a Finite Element Method (FEM) model of the antenna and is not based on real measurements. It is confirmed that the FEM model does indeed improve the sensitivity and gain-elevation curve for high frequency observations from the secondary focus, but further improvements from real measurements are likely possible. Within the scope of this thesis a general OOF holography software (pyoof package) was developed that takes care of the particular geometry and blockage of the Effelsberg antenna. It solves the under-determined problem of the observed power pattern and aperture distribution relation, that is required for the phase-retrieval computation of the OOF holography. Several OOF holography observation campaigns were performed, including consistency checks, e.g. through the introduction of known misalignments in the active surface and the comparison of measurements with the FEM model on and off. The measurements show that the basic principle works and that surface adjustments are possible. Finally a new look-up table was proposed for fixed elevations with guidelines on how to model gravitationally-caused surface deformations for future observing campaigns and therewith improve the gain-elevation curve. Referees: Prof. Dr. Karl Menten, Prof. Dr. Pavel Kroupa

	Lunch Colloquium
Dr. Robert Wharton	ORATED

MPIfR

The timing of pulses from a radio pulsar in orbit around the supermassive black hole Sgr A* would provide the precise measurements needed to test fundamental predictions about black holes. Unfortunately, such a pulsar has not been discovered yet. I will briefly discuss a few reasons why such a pulsar may have eluded detection and describe ongoing searches using new pulsar observing modes available at the Karl G. Jansky Very Large Array (VLA). These VLA searches are some of the most sensitive to date and offer an excellent opportunity to characterize the canonical pulsar population within about 20 pc of Sgr A*.

	Special Colloquium
Prof. Gerhardt Meurer	ORATED

ICRAR, Perth, Australia

Our universe has passed the peak of star formation activity. Galaxies are accelerating away from each other, and their evolution is becoming more dominated by secular processes. Indeed, observations show that galaxy disks have reached an equilibrium stability throughout their optically bright portions and beyond. I will show that the assumption of a uniform stability provides a good model for the structure of present day disk galaxies. It allows us to resolve some puzzles and provides a bridge between star formation, the gas and dark matter within galaxies. I will describe our current work on the constant stability disk models and prospects for understanding the main-sequence of star forming galaxies and their evolution.

	Promotionskolloquium
Fang-Chun Liu	ORATED

MPIfR

Water is an essential molecule to oxygen chemistry and to the proliferation of life. Also, it is the main constituent of icy grain mantles in the Universe. The formation of water can be studied through the HDO/H2O ratio. Thanks to the launch of the Herschel Space Observatory and the advance of sensitive sub millimeter receivers on ground-based telescopes, many H2O and HDO transitions can now be observed, enabling more accurate studies of the level of water fractionation, i.e., the enhancement of the HDO/H2O abundance ratio over the D/H elemental ratio. Using these new technologies, we aim at revisiting the water fractionation studies toward star-forming regions. We present here detailed studies of the D/H ratios of water in one low-mass protostar and six luminous high-mass star-forming regions. Deuterated water and H2-18O has been detected in these sources with APEX, SMA and Herschel Space Observatory. We analyzed these observations using the 1D radiative transfer code RATRAN to obtain the HDO and H2-18O fractional abundances throughout the envelopes. The results show that the HDO fractional abundances in the inner and outer regions are different by more than two orders, which implies that the sublimation is very similar in low- and high-mass star-forming regions. Previous and our studies show that the values of the HDO fractional abundance in star-forming regions with different masses do not correlate with their evolution. The H2O abundance is deduced from the analysis of the H2-18O transition lines. The similarity of the measured HDO/H2O ratios suggests that the chemical evolution of water is the same regardless of the masses of the regions. [Referees: Prof. Dr. Karl M. Menten (MPIfR), Prof. Dr. Pavel Kroupa (HISKIP), Prof. Dr. Stephan Schlemmer (Physikalisches Institut, Uni Köln), Prof. Dr. Gerhard von der Emde (Institute of Zoology)]

	Special Colloquium
Dr. Chau Ching Chiong	ORATED

Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan

ALMA covers the frequency band from 35 GHz to 960 GHz in 10 frequency bands. In the talk, the design and the performance of the ALMA Band 1 receiver front-end covering 35 to 50 GHz will be presented. Different from ALMA Band-3 to -10, the Band 1 receiver is an HEMT-based receiver with cryogenic HEMT amplifier as the first stage in the receiving path. Operation under 15 K environment, the receiver shows the state-of-the-art performance with the noise temperature of 16 to 31 K and the image band rejection ratio of over 30 dB. At the moment, the first 8 receiver cartridges are under testing and we expect to perform the integration test at the OSF soon. The future Band 1 production and delivery timeline and the science verification plan will also be presented in the talk.

	Main Colloquium
Prof. Vitor Cardoso	ORATED

Instituto Superior Técnico, Lisbon

This year marks the centenary of two pivotal breakthroughs in physics: the discovery of the Schwarzschild solution, describing a non-rotating black hole, and Einstein's prediction of gravitational waves. Gravitational waves offer a unique glimpse into the unseen universe in different ways, and allow us to test the basic tenets of General Relativity, some of which have been taken for granted without observations: are gravitons massless? Are black holes the simplest possible macroscopic objects? do event horizons and black holes really exist, or is their formation halted by some as-yet unknown mechanism? Do singularities arise in our universe as the outcome of violent collisions? Can gravitational waves carry information about the nature of the elusive dark matter? In this talk, I will describe the science encoded in a gravitational wave signal and what the upcoming years might have in store regarding fundamental physics and gravitational waves.

	Master Colloquium
Silvia Nösel	ORATED

MPIfR

Microquasars are excellent laboratories to study the accretion-ejection coupling in accreting compact objects. Microquasars are binary stellar systems, where a compact object accretes from a normal star. From the accretion disk and inflow, emitting X-rays, is launched a relativistic jet, emitting in the radio band. Timing analysis of variability is the powerful tool to investigate on variations around the accretion flow and on their relationship with variations in the jet. Variability in the characteristic of quasi-periodic oscillations (QPO) with timescales of minutes/hours have been observed up to now only in few microquasars. Only in one of them, the black hole X-ray binary GRS1915+105, a link between QPOs in the accretion flow and in the jet has been observed. One major issue is, if these kind of QPOs are always present or dominating the onset only or the decay only of large radio outbursts. With this respect the system LSI+61°303 with its periodic orbital large radio outbursts would represent the favourable target for QPO observations. In the past only hints for QPOs with timescales of minutes/hours were observed in LSI+61°303. We analyse new and archived observations using several timing analysis techniques. New observations by the Westerbork Radio Telescope at 2.3 GHz reveal significant and stable 55 minutes QPOs on four consecutive days. Archived X-ray Suzaku observations show significant QPO of 2.4 hours and X-ray XMM-Newton observations show evidence for QPO of 4 hours. These results corroborate the presence of same time scale QPOs at low and high energy in LSI+61°303. Future simultaneous radio and X-rays observations in LSI+61°303 can reveal how QPOs in the accretion flow are linked with QPOs in the outflow and provide observational basis for an improvement in our understanding of the accretion-ejection physical processes. [First Advisor: Priv.-Doz. Dr. Maria Massi; Second Advisor: Prof. Dr. Karl M. Menten]

	Special Colloquium
Dr. Marian W. Pospieszalski	ORATED

NRAO Charlottesville

Improvements in the noise temperature of field-effect transistors (FET's) and, later, heterostructure field-effect transistors (HFET's) over the last several decades have been quite dramatic. In 1970, a noise temperature of 120 K was reported at 1 GHz and physical temperature of 77 K. By 2010, noise temperatures of 3, 10 and 25 K were reported at 10, 40 and 100 GHz, respectively, for physical temperatures of about 15 K. These values of minimum noise temperatures in respective bands are typical of cryogenic low noise amplifiers built for EVLA and GBT receivers and for ALMA band 1 and 2 receivers. In the first part of the presentation, the developments in this field are briefly traced and an attempt is made to identify important milestones. Examples of experimental results obtained with different generations of FET's (HFET's) are compared with the model predictions. The current state of the art in cryogenic low noise InP HFET's is presented and compared with SiGe HBT results. The second part addresses the question of possible future progress in transistor noise performance. For that purpose, noise models of unipolar and bipolar transistors are reviewed with emphasis on certain properties of noise parameters which are common to all microwave low noise transistors. The limits on allowable values of noise parameters of microwave transistors are reviewed. Specifically, the influence of further progress in gate length reduction of FET's and technology of artificially structured III-V semiconductors on achievable minimum noise temperatures (noise figures) is examined. The existence of natural limits on noise performance of field effect transistors is demonstrated, leading to a conclusion that significant improvements in minimum noise temperature from further scaling of gate length may not be expected in any FET technology.

	Main Colloquium
Prof. Jes Jørgensen	ORATED

Niels Bohr Institute, University of Copenhagen

Low-mass stars like our Sun are formed in the centers of dark clouds of dust and gas that obscure their visible light. Deep observations at infrared and submillimeter wavelengths are uniquely suited to probe the inner regions of these young stellar objects and unravel their structures, as well as the physical and chemical processes involved. These earliest stages are particularly interesting as it is in these stages that the first seeds for the chemical evolution of the protoplanetary disk are planted and where some complex organic, possibly prebiotic, molecules are formed. For this topic ALMA is providing important observational constraints with its high sensitivity for faint lines, high spectral resolution which limits line confusion, and high angular resolution making it possible to study the physical and chemical evolution of material as it is falls in from large scales of molecular clouds to circumstellar disks. In this talk I will discuss the constraints on the chemical structure of deeply embedded protostars offered by recent ALMA observations. I will show how we can use systematic surveys with ALMA to shed new light on the formation of complex organics and investigate the link between the physical and chemical structure of deeply embedded protostars on solar-system scales.

	Main Colloquium
Dr. Sibylle Anderl	ORATED

IPAG Grenoble and Frankfurter Allgemeine Zeitung

Astrophysics, insofar it is concerned with objects outside of our solar system, is an observational science: it is impossible to directly interact with cosmic phenomena and to perform experiments on them in a sense that hypotheses are investigated by means of controlled test conditions. The missing possibility of direct intervention, marking the difference between observational and experimental sciences, puts the astronomer in a situation in which he or she is only able to study the information sent out by the astronomical objects spontaneously. The philosopher Ian Hacking was convinced that these methodological restrictions set astrophysics fundamentally apart from the experimental sciences. In particular, he stresses the inherent uncertainty of astrophysical knowledge that seems to be related to a strong underdetermination on several levels. Underdetermination, however, is a problem that all scientific disciplines have to face. It describes the idea that all the given evidence we have at a time may not be sufficient to determine what we should think about it. In order to decide whether this problem is indeed particularly severe in astrophysics, I will take a closer look at the astrophysical research method and contrast it with the research methods in other fields of science. In particular, I will focus on two elements of the astrophysical methodology, the Sherlock Holmes method and the use of the cosmic laboratory.

	Special Colloquium
Prof. Dr. Richard Wielebinski	ORATED

MPIfR

Magnetic fields are omnipresent in the Universe. We know of records by the Chinese or the Greeks in which magnetic effects were discussed. Certainly the navigation of ships in the middle ages depended on the use of the compass. The first experiments with magnets were described by Gilbert in 1600. Johannes Keppler speculated on the magnetic effect that was forcing the movement of the planets. This suggestion was negated by Isaac Newton who developed the gravitational theory. Finally the electromagnetic theory was developed by James Clerk Maxwell that described the action of electric current and magnetic field. Practical devices as the dynamo or electric motor came from this theory. Peter Zeeman made measurement of magnetic field at a distance by observing the splitting of line emission in a magnetic field. Very soon after the Zeeman Effect was postulated the first measurements of magnetic fields were made by Hale in the Sun in 1908. The discovery of cosmic radio waves by Karl Jansky in 1932 added another method of measuring magnetic fields -- the cosmic radio waves were due to a non-thermal emission process -- the action of relativistic particles in magnetic fields. Since this synchrotron emission is polarized the study of the polarization of the cosmic radio waves allows the determination of magnetic fields. I have become involved in studies of polarization of Galactic radio waves during my PhD studies in Cambridge 1960-1963. The first radio detections of magnetic field in a cosmic object, the Crab nebula, were made in 1957. In the summer of 1962 the first unambiguous detection of the polarization of Galactic radio waves and hence of magnetic fields in the Milky Way were added. The whole year 1962 may be termed a magnetic year. Polarization was detected in radio galaxies, and in supernova remnants. In 1968 pulsars were discovered and showed unusual polarization properties. The elusive radio Zeeman Effect was finally detected in 1968 using the HI line emission in selected Galactic regions. The studies of magnetic fields have started in 1962 and go on to the present day. The 100m radio telescope in Effelsberg played a significant role in this research field.

	Master Colloquium
Arshia Maria Jacob	ORATED

MPIfR

The Heterodyne Instrument for the Far-Infrared (HIFI) on board Herschel revolutionized the study of interstellar hydrides. HIFI observed the lowest lying rotational hyperfine structure transitions of CH at 533 and 537 GHz in absorption. This triggered new interests in this radical's role in the chemistry of diffuse and translucent clouds while also garnering more appreciation for it as a reliable tracer for molecular hydrogen in such regions. With the end of the Herschel mission, the Stratospheric Observatory for Infrared Astronomy (SOFIA) has created a new avenue for procuring CH data. To account for CH's hyperfine structure (hfs), a robust algorithm based on the Wiener filter was developed to deconvolve the hyperfine weights from the observed spectrum and was applied to spectra covering the sightlines towards W49 N and W51 e1/e2. The column densities of CH that were derived from the deconvolved spectra establish this transition as a tool for ultimately measuring the column densities of molecular hydrogen. In addition, the ground state radio lines of CH observed near 3 GHz using the 100m Effelsberg telescope show three hfs transitions that lie between Lambda-doublet levels. The excitation of these lines was found to be inconsistent with the assumption of local thermodynamic equilibrium (LTE) requiring non-LTE radiative transfer analysis. Sharing a characteristic doublet pattern with the 2 THz transitions, a synergy exists between the two observational regimes. The column densities derived using the Wiener filter algorithm were used to constrain the 1-D non-LTE radiative transfer grids. Further investigating the physical and excitation conditions via the non-LTE analysis urges the need for better collisional rate coefficients. Supervisors: Prof. Dr. Karl Menten, Prof. Dr. Pavel Kroupa (PD. Dr. Maria Massi)

	Lunch Colloquium
Dr. Nicholas R. MacDonald	ORATED

Max-Planck-Institut für Radioastronomie

Blazars are the most luminous persistent and enigmatic objects in the sky. By monitoring the polarized emission of these jets and subsequently modeling flares in the high-energy emission, we are able to gain insight into the parsec-scale physics of the jets close to the central engines. In this talk I will present several recent theoretical models of high-energy blazar emission developed by the Boston University Blazar Group.

	Special Colloquium
Dr. Chris Carilli	ORATED

NRAO, Socorro, NM, USA

Inspired by dramatic discoveries from the Jansky Very Large Array, and the Atacama Large Millimeter Array, the astronomy community is considering a future large area radio array: the 'Next Generation Very Large Array' (ngVLA). The ngVLA design entails an interferometric array with 10 times larger effective collecting area and 10 times higher spatial resolution than the current VLA and ALMA, optimized for operation in the frequency range 10GHz to 50GHz, with reasonable performance over 1.2GHz to 115GHz. The ngVLA is optimized for observations at wavelengths between the superb performance of ALMA at submm wavelengths, and the future SKA-1 at few centimeter and longer wavelengths. The ngVLA opens a new window on the Universe through ultra-sensitive imaging of thermal line and continuum emission down to milliarcecond resolution, as well as unprecedented broad band continuum polarimetric imaging of non-thermal processes. These capabilities are the only means with which to answer a broad range of paramount questions in modern astronomy, ranging from direct imaging of planet formation in the terrestrial-zone, to studies of dust-obscured star formation and the cosmic baryon cycle down to pc-scales out to the Virgo cluster. The ngVLA will implement novel techniques to explore temporal phenomena from milliseconds to years. The ngVLA covers a frequency range which may be optimal for finding the electromagnetic counterparts to gravity wave sources, and to search for pulsars orbiting the supermassive black hole in the Galactic center. I will highlight recent studies of the evolution of the cool gas content of galaxies, in particular from the ASPECS large program on ALMA. These results demonstrate the progress in our understanding of the evolution of the fuel for star formation in galaxies, as well as accentuate the limitations to such studies that can only be overcome through a telescope like the ngVLA. I will present the current design and parameter space, and the process of community studies driving design specifications.

	Main Colloquium
Dr. Volker Perlick	ORATED

ZARM, Universität Bremen

According to general relativity a black hole casts a shadow if it is seen against a bright backdrop of light sources. The best candidates for actually observing this shadow in the near future are the compact objects at the centre of our galaxy and at the centre of M87. In this talk I will concentrate on situations where the shadow can be calculated analytically. This includes the entire class of so-called Plebanski-Demianski metrics which describe black holes with mass, spin, electric and magnetic charge, NUT parameter, cosmological constant and acceleration parameter. I will also address the question of how the shadow is influenced by a (cold and non-magnetised) plasma.

	Lunch Colloquium
Dr. Veselina Kalinova	ORATED

MPIfR

The shape and the amplitude of the circular velocity curves (CVCs) reflect the mass distribution of both luminous and dark matter in galaxies. We inferred 238 CVCs of nearby galaxies using CALIFA stellar dynamical models (Kalinova et al., 2017, MNRAS, 469, 3, p.2539; http://adsabs.harvard.edu/abs/2017MNRAS.469.2539K) with a diversity in morphological types - from elliptical to late-type spiral galaxies. We applied principal component analysis (PCA) to the CVC shapes to find characteristic features and use the k-means clustering to separate the circular curves into classes. Our method identified four different classes, which we named Slow-Rising (SR), Flat (FL), Round-peaked (RP) and Sharp-peaked (SP) circular curves. We found trends between CVC classes and common properties of the galaxies, which help us to draw global conclusions for their internal structure, formation, and evolution. SR-CVCs are typical for low-mass, late-type (Sb-Sdm), young, faint, metal-poor, and disc-dominated galaxies, while SP-CVCs are typical for high-mass, early-type (E1-E7), old, bright, metal-rich and bulge-dominated galaxies. FL-CVCs and RP-CVCs appear presented by galaxies with intermediate mass, age, luminosity, metallicity, bulge-to-disc ratio and morphologies (E4-S0a, Sa-Sbc). We also found an interesting trend of the slopes of the CVCs with the stellar masses of the galaxies, showing two parallel linear sequences at low-mass and high-mass galaxies, respectively, and a large dispersion in the region of intermediate masses. We conclude that the maximum amplitude, slope, and shape of the CVCs appear key ingredients for understanding the dynamical evolution of the galaxies. Complementary VLA-HI and CARMA-CO high-resolution observations will shed more light on the mass distribution of the galaxies, and on the possible universal connection between the five main Principal Component vectors of the CVCs of the galaxies and their Dark Matter halo density profiles.

	Special Colloquium
Dr. Natalia Lewandowska	ORATED

Green Bank Observatory

Since its detection in 1968 the Crab pulsar has been extensively studied over large parts of the electromagnetic spectrum, ranging from radio wavelengths to gamma-rays. The characteristics of its radio emission imply the existence of a coherent emission mechanism, whereas the observed emission at higher energies indicates an additional incoherent emission mechanism. To provide a deeper understanding of possible emission mechanisms responsible for the observed multiwavelength emission from the Crab pulsar, we observed its radio Giant Pulses and gamma-ray emission simultaneously with the Effelsberg radio telescope, the Westerbork Synthesis Radio Telescope and the Major Atmospheric Gamma Imaging Cherenkov telescopes. In the scope of an extended study we searched for a correlation between radio Giant Pulses and gamma-ray photons from the Crab pulsar. In this talk I would like to present the results of the corresponding multiwavelength study.

	Master Colloquium
Mohsen Shamohammadi	ORATED

MPIfR

Binary pulsar systems, in particular double neutron stars, are of interest as they can be used as tools for testing theories of gravity (like Einstein’s theory of general relativity), investigating binary evolution, and measuring neutron star masses. The population of merging binaries also has implications for the detection rate of ground based gravitational wave detectors. Due to their orbital motion, the period of the pulsar appears to change, making these systems difficult to detect using traditional methods (FFT). So far this has been addressed using acceleration searches which attempt to recover the lost S/N by approximating this period change with a linear acceleration for the duration of the observations. This approximation is limited to observations that are 1/10 of the orbital period or less. Of course we would ideally like to find even more extreme systems in tighter orbits, potentially a PSR-BH system. This approximation can be extended by introducing jerk, the derivative of acceleration. Thus far such a search has been too computationally expensive. In this work we investigate the covariance between acceleration and jerk in order to reduce the number of trials required, potentially allowing it to be used in a full scale survey. We compared the S/N of the search acceleration only and the acceleration and jerk search results to that of an identical isolated system to determine the S/N recovered. This allowed us to characterize the detectability of the pulsar not only in different parts of the orbit but also for observations longer than one tenth of the orbit. As an example, for a binary system with a pulsar mass of 1.4 M☉, companion mass of 30 M☉, eccentricity 0.1, spin period 25 ms, and orbital period 2.4 hr, our results confirmed that adding jerk improves sensitivity by ∼ 10% for the observation time of ∼ 6% of the orbital period and by ∼ 40% for the observation time of ∼ 12% of the orbital period. The acceleration and jerk search is capable of extending the observations beyond 10% of the orbit. Also adding the jerk search not only worked in the phases of the orbit with maximum acceleration, but also over the whole orbit. We showed that jerk does improve our sensitivity generally and this was the most important for the tight binary systems with companion mass bigger than 0.1 M☉ and orbital periods more than ∼ 1 hour and spin period bigger than ∼ 40 ms with the observation time of ∼ 6% of the orbit. [Referees: Prof. Dr. Michael Kramer, Prof. Dr. Norbert Langer]

	Special Colloquium
Dr. Mercè Crosas	ORATED

Harvard Institute for Quantitative Social Science

Research generates more data than ever before. These data lead to new findings, disprove hypotheses, and are fundamental to understanding research results. However, often published findings are available to researchers while data supporting those findings are not accessible. Data sharing or publishing, is a relatively recent term defined as the release of research data, associated metadata, accompanying documentation, and software code for re-use and analysis in such a manner that they can be discovered on the Web and referred to in a unique and persistent way. Sharing avoids duplication of expensive experiments, speeds up health and medical scientific discoveries, and is needed to reproduce and verify published findings. So why are not all researchers sharing their data? Several factors contribute: incentives for sharing are not clear, technologies for sharing are not readily available, and privacy concerns make sharing difficult. The Dataverse project, started in 2006 at the Institute for Quantitative Social Science at Harvard University, addresses all of these issues, reduces barriers, and helps make data sharing common practice in research. Dataverse software enables building repositories for research data that follow best practices for making data FAIR (Findable, Accessible, Interoperable, and Reusable) while incentivizing researchers by giving credit to authors through a formal and persistent data citation which can be directly used in bibliographic references. It allows authors to create rich metadata describing a data set so that it can be reused by others, as well as defining terms of use or licenses to protect data when privacy issues arise. Data sharing is already bringing transparency and validation to scientific fields.

	Main Colloquium
Prof. Manfred Stöckler	ORATED

Institut für Philosophie der Univ. Bremen

When do results of measurements of stellar orbits, special X-ray emissions, and near-infrared emissions from the location of the radio source Sagittarius A* give good reasons that we have found a supermassive black hole? One should expect that philosophy of science could supply some general criteria for an answer to such a question. But the philosophical advise is disappointing. Contemporary philosophy of science is still strongly influenced by the concepts introduced by the movement of logical empiricism hundred years ago. This logical approach was not prepared to develop a sophisticated analysis of observations and of the empirical confirmation of theories. Later on, case studies showed the complexity of empirical tests of hypotheses and theories: You need subsidiary hypotheses to deduce consequences of the theory that can be confronted with experimental data. These data are obtained with the help of measurements designed and read with the help of the given theory and of further theories (cf. M. Bunge, Philosophy of Physics, p. 213). All in all, the growing interest in experimental work that has evolved during the last three decades referred more to historical and sociological aspects than to methodological questions. So general rules and conclusive philosophical criteria for evaluating the success of observations still are missing. Nevertheless, there are some proposals for more local solutions (e.g. coherence, inference to the best explanation, high value for predicting new independent evidence). We shall discuss the epistemological problems of these proposals and try to apply them to the observation of black holes. The debate on the theory/experiment interface has consequences if we look for sufficient evidence for the existence of black holes. The reasons why we believe in the existence of objects (for example of black holes) are similar to the reasons why we believe in theories. So we could find good, but no conclusive empirical arguments for the existence of black holes. An open-ended question remains: Can philosophers of science give normative recommendations? Do they have more tools than describing what physicists do and applying the principle of reflective equilibrium?

	Special Colloquium
Mr. János Botyánszki	ORATED

University of California, Berkeley

Type Ia Supernovae (SNe Ia) are thought to be thermonuclear explosions of white dwarfs (WDs), but their exact progenitor systems are still unknown. Leading models propose that either a Chandrasekhar-mass WD explodes after a period of steady accretion from a binary companion, or two WDs interact through a merger or helium accretion leading to a pure detonation of a sub-Chandrasekhar-mass WD. Hydrodynamical simulations of the former scenario predict that the explosion of the WD results in solar-metallicity material being stripped from the binary companion and embedded into the ejecta, which should be visible at late times (in the "nebular phase"). However, H/He have never been detected in nebular observations of SNe Ia, and there has been little theoretical modeling done to convert the observed non-detections into constraints on stripped mass. Here we present theoretical work on spectral line formation to probe the conditions that lead to H/He emission at late times and show (the first ever) multi-dimensional synthetic spectra of companion-interaction models with a variety of binary companion properties.

	Main Colloquium
Dr. Odele Straub	ORATED

LESIA, Observatoire de Paris

Accretion discs around black holes are gigantic power plants that convert the gravitational potential energy of in-falling matter into heat. The inner parts of accretion discs in stellar-mass black hole binary systems can get so hot that they emit X-ray radiation. This X-ray light often exhibits rhythmic, nearly periodic pulses. These are the quasi-periodic oscillations (QPOs) which typically occur at multiple frequencies that are connected to radii very close to the black hole. The nature of QPOs has been a mystery for over 20 years, only recently theoretical and observational studies helped forming a better picture of what is going on, when accretion discs wobble.

	Special Colloquium
Prof. Keiichi Ohnaka	ORATED

Universidad Catolica del Norte, Instituto de Astronomia, Antofagasta, Chile

Studies of the mass loss from stars in late evolutionary stages are of utmost importance for improving our understanding of not only stellar evolution but also the chemical enrichment of galaxies. Despite such importance, the mass loss from cool evolved stars is one of the long-standing problems in stellar astrophysics. Milliarcsecond resolution achieved by optical/infrared long-baseline interferometry provides a unique opportunity to spatially resolve this innermost key region. We have recently succeeded not only in imaging the surface of the red supergiant supernova progenitor Antares in the 2.3 micron CO lines in unprecedented detail but also in witnessing, for the first time, the complex gas dynamics over the surface and atmosphere of the star. Our two-dimensional velocity field map of Antares reveals vigorous upwelling and downdrafting motions of large gas clumps in the atmosphere extending out to 1.7 stellar radii. This suggests that the mass loss in red supergiants is launched in a turbulent, clumpy manner, not in a spherical, ordered manner as is often assumed. Our work opens an entirely new window to observe stars just like in observations of the Sun.

	Main Colloquium
Dr. Daniel Lenz	ORATED

Jet Propulsion Laboratory, NASA, USA

With the ever-increasing sensitivity of telescopes and instruments, one bottleneck in precision cosmology is the accurate removal of foreground emission from the Milky Way Galaxy. This applies to many different fields, such as de-lensing in high-resolution CMB data, accurate reddening estimates for BAO experiments, or intensity mapping efforts. I review some of the current limits and ideas that are used to address these issues, with an emphasis on reddening by Galactic dust and on new maps of the cosmic infrared background. Here, I will present a new HI-based map of interstellar reddening that address many of the systematics in the often-used reddening map by Schlegel, Finkbeiner, and Davis (1998). For the CIB, I will highlight cross correlations with other tracers of the large-scale structure, which make the CIB a highly efficient cosmological probe.

	Special Colloquium
Dr. Luke Chamandy	ORATED

University of Rochester

Conventional mean-field galactic dynamo theory is a simple and elegant theory designed to explain the structure and evolution of large-scale magnetic fields in disk galaxies. Coupled with more recent developments that take into account magnetic helicity balance, this theory is capable of describing quantitatively the growth and non-linear saturation of regular magnetic fields. Taking advantage of the thin-disk geometry makes it possible to adopt approximations that simplify the governing equations further. This results in remarkably simple but accurate and predictive models relying on only a handful of parameters that are observationally constrained to varying degree. What are the relevant quantitative predictions of these models, and how well do they stack up to observations of nearby galaxies? In this talk I will argue that the so-called magnetic pitch angle, which characterizes the direction of the component of the field parallel to the disk midplane, is a key quantity for observationally testing the theory, and I will describe recent work that directly compares theory and observation. I will also touch on some intriguing new theoretical developments.

	Promotionskolloquium
Alessandro Ridolfi	ORATED

MPIfR

Pulsars are fast-rotating, highly-magnetized neutron stars that turn out to be outstanding natural laboratories for a wide range of scientific applications. Globular clusters (GCs), spherical, gravitationally bound groups of stars orbiting the Milky Way, are very efficient pulsar "factories". Their extremely high densities, especially near their cores, greatly favour the dynamical interaction of stars and, thus, the formation of exotic binary systems. For my PhD thesis, I have worked on multi-decade observations of 47 Tucanae (47 Tuc) and M15, which are two among the richest GCs for the number of pulsars hosted, having 25 and 8 known such objects, respectively. In the first part of this colloquium, I will report on the long-term timing of all the 47 Tuc pulsars. After being characterized individually, the pulsars are used collectively to constrain important properties of the host cluster. Among these are the proper motion of the cluster as a whole, the motion of the pulsars relative to each other, the cluster distance as well as the hypothesis of an intermediate-mass black hole residing at the center of 47 Tuc. In the second part of the colloquium, I will focus on PSR B2127+11C, a relativistic binary pulsar in a double neutron star system, located in the globular cluster M15. I will show how the pulsar is undergoing dramatic changes in its pulse profile properties because of relativistic spin precession (RSP), an effect predicted by General Relativity. Thanks to full-Stokes observations carried out with the Arecibo radio telescope, I have studied the variations of the polarimetric properties of PSR B2127+11C over time to model RSP and constrain the system geometry. Referees: Prof. Dr. Michael Kramer (Max-Planck-Institut für Radioastronomie) Prof. Dr. Norbert Langer (Argelander­Institut für Astronomie) Prof. Dr. Klaus Desch (Physikalisches Institut) Prof. Dr. Theo Bakker (Institut für Evolutionsbiologie und Ökologie)

	SFB Colloquium
Dr. Henrik Beuther	ORATED

MPIA, Heidelberg

Star formation processes are important over a huge range of physical scales, from extragalactic star formation via large molecular clouds down to the scales of individual protostellar disks around stars. Linking these scales is crucial for a general understanding of star formation and the interstellar medium. I will set into context results from the nearby galaxy NGC3627 with large-scale clouds in the Milky Way and the fragmentation and disk formation processes within individual high-mass star-forming regions.

	Special Colloquium
Dr. Glennys Farrar	ORATED

New York University

I will report on the progress on a “next generation” Galactic magnetic field (GMF) model, obtained together with Michael Unger. The general approach follows that of Jansson-Farrar 2012 (JF12) which models the field with a superposition of divergence-free functions describing the coherent field with disk, toroidal halo and poloidal components and the random component with disk and halo components, and determines the parameters of the field model by fitting all-sky Faraday rotation measures (RMs) and synchrotron emission maps. We aim to develop more physical and better-constrained models of thermal and cosmic-ray electron densities than currently available. I will present results of using a number of different synchrotron data products and models of n_e and n_cre which have become available, using the original JF12 functional forms as well as several variants. We also consider (anti-)correlations between field strength and electron density. The range of field models which emerge from these variations on the JF12 analysis provides a measure of the present uncertainty on the GMF. I will also present very recent results the RMs and polarized synchrotron emission of external galaxies, based on the GMF and on the cosmological MHD simulation of Springel’s group.

	Main Colloquium
Prof. Robin Shelton	ORATED

Department of Physics and Astronomy, University of Georgia

Astronomical observations have found enormous and fast-moving gas clouds near the Milky Way Galaxy and near other large spiral galaxies. Some are near the rarefied outskirts of their host galaxy, while others are poised to collide with the disk. With speeds in excess of 100 km/sec and masses that can easily exceed a million solar masses, they can bring both disruptive power and fresh material to a galaxy. My group has been computationally modeling these fast-moving clouds, called high velocity clouds (HVCs). In various simulations, we consider the effects of dark matter, magnetic fields, and non collisional ionizational equilibrium of the metal atoms. Our goal is determine how HVCs interact with galaxies. In this presentation, I will show how HVCs evolve on timescales of hundreds of millions of years as they travel through the circumgalactic and halo regions and through galactic disks, and how they seed the halo with warm gas, condense and capture halo material, and punch holes in the galactic disk.

	Special Colloquium
Dr. habil. Yuri Y. Kovalev	ORATED

ASC Lebedev

We have compared the secondary dataset of Gaia DR1 and the VLBI catalogue RFC. We found over 6000 matching sources that are almost exclusively active galaxy nuclei. The median uncertainty of VLBI is a factor of 4 better than Gaia DR1. We found a population of sources with statistically significant positional offsets. We provide evidence that these offsets are not artifacts of data analysis but have a physical nature. The offsets have a preferred direction along or opposite to the jet direction and scale from 0 to more than 10 mas. We explain this as a manifestation of extended optical structure of AGN jets at milliarcsecond level or the core-shift effect related to synchrotron opacity. The presence of the optical structure has a number of important implications to Gaia astrometric analysis as well as provides a new exciting window of opportunity to study physics of active galaxy nuclei.

	Special Colloquium
Veena Vadamattom Shaji	ORATED

Indian Institute of Space science & Technology

Star forming regions in the southern sky are relatively less studied compared to their northern counterparts. In this context, I will present the results of our multi-wavelength analysis towards few southern molecular clouds, with specific emphasis on IRAS 17256-3631. Our analysis of the star forming activity of these regions cover a wide-wavelength range, from near-infrared to radio. While the embedded cluster and warm dust components are examined using infrared wavelength bands, the radio continuum has been used to probe the ionised gas. We have also mapped the low frequency radio recombination line (RRL) emission using GMRT, India. This is the first RRL mapping study of HII regions at low frequency bands (1.3 GHz) and we explain the observed continuum morphology using the kinematics of RRLs. In addition, we analyse the broadening of these lines by various mechanisms. Finally, we compare the star-forming activity in the clumps of the molecular clouds, by combining the information extracted using a plethora of tracers from different wavelength bands.

	Informal Colloquium
Prof. Eduardo Ros	ORATED

MPIfR

The last meeting of the Chemistry, Physics and Technology Section of the Scientific Board of the Max Planck Society took place on June 21st in Weimar, followed by the General Assembly on June 22nd in Erfurt. As the representative of the scientists of the MPIfR, I will report from this meeting and also from the previous one on February in Berlin, not reported yet in this forum.

	Informal Colloquium
Prof. Tom Megeath	ORATED

University of Toledo, Ohio

I will discuss the results of a detailed study of 330 protostars in the Orion Molecular Clouds utilizing the Herschel, Spitzer, HST, ALMA, VLA, IRTF and DCT telescopes. Using these data, I will assess the different processes that regulate mass accretion onto protostars incuding envelope infall, feedback by outfows, disk accretion, and formation environment. I will also over current results from an HST and ALMA study of edge-on protostars designed to probe the role of envelope angular momentum in determining disk properties. Finally, I will give a brief status report on ALMA and VLA surveys for disks around protostars. By coupling these data with near-IR spectroscopy of the young protostars, the mases and radii of a sizeable sample of protostars can be determined in the next few years, providing observational constraints on the initial conditions for pre-main sequence contraction.

	SFB Colloquium
Dr. David Elbaz	ORATED

CEA Saclay

Local galaxies exhibit a bimodal distribution. Red-dead galaxies are more clustered than blue-star forming galaxies suggesting that galaxies are social beings whose life depends on their environment. In apparent contradiction, evidence has been accumulated for a universality of the star-formation history of galaxies independently of their environment. The so-called main sequence of star forming galaxies indeed suggests that it is their mass that controls the history of galaxies; in situ mechanisms being more important than ex situ ones. I will review recent results obtained with the combination of Herschel and ALMA and discuss this apparent contradiction between the respective roles of in situ and ex situ mechanisms in the history of galaxies. I will present a population of distant massive star-forming galaxies that were missed by the standard Lyman-break technique and discuss their role on the origin of compact early-type galaxies seen at z~2, whose progenitors have been missing until now. The most extreme of these, missed even in the deepest HST NIR images, now jump to the eye with ALMA. I will show that these massive distant galaxies follow the universal star-forming main sequence up to z=4. Their closer siblings studied at z=2.5 trace the most distant massive galaxy cluster caught at the very epoch of its formation. I will then discuss possible physical mechanisms at play in these galaxies. Do giant kpc-clumps of star formation play an important role in the mass growth of a galaxy? What is the role of galaxy mergers vs violent dynamical instabilities? Is there a negative or positive effect of active nuclei in the stellar mass growth of galaxies?

	Lunch Colloquium
PD Dr. Silke Britzen	ORATED

MPIfR

OJ 287 is the best candidate for hosting a supermassive binary black hole (SMBH) with masses of 10^10 and 10^8 solar masses. Periodicities in the historical optical light-curve have been modeled successfully within a SMBH scenario. However - so far it has proved difficult to relate the morphological changes of the pc-scale radio jet to the strong variability and periodicities detected in the optical and radio light-curves. We revisit this problem by re-analyzing 118 epochs of 15 GHz MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA experiments) data covering the time between April 1995 and January 2017. I will present and discuss our recent results.

	Special Colloquium
Erin Boettcher	ORATED

University of Wisconsin, Madison

In spiral galaxies like the Milky Way, multi-phase, gaseous halos are threaded by extraplanar magnetic fields and cosmic rays. Extraplanar diffuse ionized gas (eDIG) layers have scale heights that exceed their thermal scale heights by a factor of a few, suggesting that non-thermal pressure gradients may play an important role in setting their scale heights. By characterizing the thermal, turbulent, magnetic field, and cosmic ray pressure gradients, we can determine if these layers are in dynamical equilibrium, or if they are evidence of a galactic fountain, a galactic wind, or an accretion flow. Here, I will discuss optical emission-line spectroscopy of the eDIG layers in two nearby galaxies, the edge-on galaxy NGC 891 and the face-on galaxy M83. For both galaxies, I will consider the rotational velocities and velocity dispersions of the gas, and the implications for magnetic field structure and magnetic dynamos. For NGC 891, I will also discuss our use of radio continuum observations from Continuum Halos in Nearby Galaxies - An EVLA Survey (CHANG-ES) to constrain the magnetic field and cosmic ray pressure gradients. These are the first in a small sample of galaxies that we will use to study the relationship between thermal and non-thermal halos in systems with a range of inclination angles and star formation rates.

	Main Colloquium
Prof. Ansgar Reiners	ORATED

Georg-August-Universität Göttingen

Culminating in spectacular discoveries during the past 10 months, the search for extrasolar planets has reached the stars in our immediate neighborhood. These stars, like 3/4 of the stars in the Galaxy, are low-mass M-dwarfs with complex molecular absorption patterns and little flux at optical wavelength. To find these planets, and to push the level to even smaller ones, Doppler measurements must be carried out at near-infrared wavelengths, be sensitive to walking speed, and we must understand surface plasma motion at the same level. I will summarize current efforts to search for planets in our cosmic backyard, highlight some developments in Doppler velocimetry, and show a project aimed at understanding stellar surface velocites that involves observations of the 2015 solar eclipse, a new solar reference spectrum observed from Göttingen, and a Laser Frequency Comb.

	Special Colloquium
Mr. Masato Kobayashi	ORATED

Nagoya University

Recent radio observations show that giant molecular cloud (GMC) mass functions noticeably vary across galactic disks (e.g., Colombo et al. 2014). High-resolution magnetohydrodynamics simulations show that multiple episodes of compression are required for creating a molecular cloud in the magnetized interstellar medium (e.g., Inoue et al. 2012). To understand time evolution of GMC mass functions, we formulate the evolution equation for the GMC mass function to reproduce the observed profiles, for which multiple compressions are driven by a network of expanding shells due to H II regions and supernova remnants. We also introduce the cloud-cloud collision (CCC) terms in the evolution equation in contrast to previous work. In this seminar, I would like to present computed time evolutions and the following two suggestions: (1) the GMC mass function slope is governed by the ratio of GMC formation timescale to its dispersal timescale whereas the CCC effect is limited only in the massive end of the profile, (2) almost all of the dispersed gas contributes to the mass growth of pre-existing GMCs in arm regions whereas less than 60 percent contributes in inter-arm regions. Our results suggest that measurement of the GMC mass function slope provides a powerful method to constrain those GMC timescales and the gas resurrecting factor in various environments across galactic disks.

	Lunch Colloquium
Dr. Eleni Vardoulaki	ORATED

AIfA

I will resent an analysis on the radio structure of 350 radio sources from the VLA-COSMOS 3GHz Large Project (JVLA-COSMOS; Smolcic et al. 2017), reaching a resolution of 0.75’’ with sensitivity of ~2.3uJy/beam. These objects were selected on the basis of their extended radio structure and were placed, by visual inspection, in radio classes that follow the FR-type classification of Fanaroff & Riley (1974). The purpose of this project is to compare the radio structure of radio AGN to their energetics (e.g. accretion properties) and environment (e.g. X-ray groups in COSMOS, George et al. 2010), and relate these to the different observed FR radio structures to understand the physical mechanisms behind the FRI/FRII dichotomy. The linear projected sizes of these objects were measured by a semi-automatic, machine learning method. We report the discovery of low radio power [log(L3GHz/W/Hz/sr)~22], small scale (~30 kpc) classical-double radio sources (FRII) at redshifts z ~ 1, which we are able to resolve due to the unprecedented resolution of 0.75 arcsec (FWHM) of JVLA-COSMOS. Regarding the black-hole accretion rate in comparison to the radio structure, we find that jet-type FRI radio sources have, on average, lower Eddington ratios (~0.001) than FRIIs (~0.01) which agrees with past studies. Nevertheless we do not see a dichotomy on FR structure when it comes to their accretion properties. Finally, in regards to environment, our results point to a scenario that FRII sources are in-falling: at redshifts z > 1 FRIIs can be located at the outskirts of the associated X-ray group, but at low redshifts (z < 0.5) they sit at the centre of the potential well.

	Special Colloquium
Dr. Carlos Carrasco Gonzalez	ORATED

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

We are at present in a very exciting era for the study of how planets form. During the previous decades, observations with powerful radio interferometers, specially the Very Large Array (VLA), have well established that planet formation is a natural consequence of the star formation process itself. Planets are most probably formed as dust evolve in the circumstellar disks around Young Stellar Objects (YSOs). It is now that the extraordinary observing capabilities of the Atacama Large Millimeter Array (ALMA) are offering us an unprecedent level of detail of circumstellar disks around YSOs. The recent ALMA observations with very high angular resolutions of several disks are revealing several structures, consequences of the dust evolution, and most probably associated with the initial stages and/or ongoing planet formation. However, the contribution of the VLA to this field has not yet finished. Instead, the VLA with its recent upgrade, is still in the race and it is indeed revealing itself as a fundamental instrument to investigate the planet formation process. It seems necessary to still observe at longer millimeter wavelengths than ALMA in order to be able to penetrate very dense regions in the disks. This is specially critical at the earliest stages and at the innermost parts of the disks where, for example, terrestrial planets are expected to form. Here, I will present some very recent observations with the VLA of two very young circumstellar disks (HL Tau and HD 169142). I will also discuss how the combination of VLA and ALMA images is what actually could provide a giant step in the understanding of the planet formation process.

	Special Colloquium
Dr. Gabriele Ponti	ORATED

MPE

The advent of XMM-Newton and Chandra led to major advancements in our comprehension of the physics at the heart of the Milky Way. I will discuss some of the most recent findings related to the present activity of Sgr A* (the supermassive black hole at the Milky Way center), the signatures of its glorious past and the traces of powerful energy releases within the central degrees of the Galaxy.

	Main Colloquium
Prof. Ilya Mandel	ORATED

Uni. Birmingham

In this talk, I will discuss recent advances in probing stellar binaries at a variety of scales. The first detections of gravitational waves from binary black hole mergers have opened up new opportunities and challenges in astrophysics. I will describe my group's efforts to extract the astrophysical evolution of massive stellar binaries from observations of gravitational waves emitted during mergers of stellar remnants. I will also discuss the promise of double tidal disruptions of stellar binaries by massive black holes to explain some very intriguing observational signatures from galactic nuclei.

	Lunch Colloquium
Dr. Adrian Tiplady	ORATED

SKA South Africa management team

Astronomy has a long history in South Africa. However, in the past decade it has been the subject of major investment that has resulted in South Africa emerging as a global partner in the international radio astronomy community. A range of technology and research programs has led to the construction of the MeerKAT radio telescope, a pre-cursor to the international Square Kilometre Array to be co-hosted by South Africa and Australia. This talk will look at these developments, and the current scientific and engineering progress of the MeerKAT.

	Special Colloquium
Dr Guilaine Lagache	ORATED

Laboratoire d Astrophysique de Marseille

The fine structure line [CII] at 158 microns is one of the brightest emission lines in the spectra of galaxies. It is considered to be the dominant coolant for neutral atomic gas in the interstellar medium. Conveniently, [CII] is redshifted into the sub-millimeter and millimeter atmospheric windows for 4.56). However, so far, [CII] studies of very distant galaxies have been limited, with detection of only a handful of galaxies. The full power of ALMA will revolutionize the field, detecting [CII] in individual galaxies in the heart of the reionization era. However, while ALMA will probably follow-up hundreds of high-redshift galaxies, its small field of view and narrow bandwidth will strongly limit its sensitivity/efficiency to conduct large unbiased spectral line surveys. Rather than detecting [CII] in selected galaxies, we propose to map in 3-D the intensity due to the [CII] line emission, a technique known as Intensity Mapping. This technique measures signal fluctuations produced by the combined emission of the galaxy population on large regions of the sky in a wide frequency (thus redshift) band, and thus increases sensitivity to faint sources. I will discuss how [CII] intensity mapping measurements can offer a straightforward alternative for tracing the large structure of galaxies at z>4.5. By measuring [CII] fluctuations, I will show how we can obtain unprecedented constraints on star formation and dust build-up at a key epoch in the Universe. I will also discuss how cross-correlation of the signals (e.g. [CII] and galaxy surveys), as well as the lower redshift (z<2) CO-line fluctuations, could be used to further understand the physics of galaxy formation and reionization. Finally I will present the CONCERTO experiment, a [CII] spectrometer capable of covering few square degrees with a high sensitivity and proposed as a new intensity mapping experiment. Our instrument would be an invaluable opportunity for the APEX collaboration and the ESO community. In addition to the main [CII] survey, we expect CONCERTO to bring a significant contribution in a number of areas, including the study of galaxy clusters and the follow-up of Herschel and SCUBA-2 deep surveys.

	Promotionskolloquium
Ancor Damas	ORATED

MPIfR

Radio polarimetric observations of galactic outflows are crucial to distinguish between various driving mechanisms. New radio images in total and polarized intensity were obtained with the EVLA and the unprecedented noise level reached allows us to detect striking new features of the ordered magnetic field of the edge-on Virgo galaxy NGC 4388. We investigate the effects of ram pressure on the ordered magnetic field of this galaxy hosting a radio halo and strong nuclear outflows. In this talk I will discuss how the detection of a faint radio halo around cluster galaxies could be used for an estimate of ICM ram pressure. Also, I will show how a precession model reproduces the structure of the nuclear outflows and can be used as a tool to study the interaction of the galaxy with the ICM. [Referees: Prof. Dr. M. Kramer, Prof. Dr. P. Kroupa, Prof. Dr. J. Dingfelder, Prof. Dr. Dietmar Quandt]

	Master Colloquium
Emranul Sarkar	ORATED

MPIfR

Radio recombination lines are important diagnostic tools to understand the kinetamics of massive star forming regions. These lines are produced in the ionizing zones surrounding young massive stars and almost unambiguously identifies HII regions. Six recombination lines from H96a to H114a are studied in this work. The data came from GLOSTAR survey which is an unbiased survey of the galactic plane that uses the wideband (4GHz - 8GHz) C-band receiver from JVLA. These lines are imaged and stacked to obtain high spectral sensitivity. A source extraction code was run on the image cube to detect line emission from compact sources.Possible HII regions are identified in the associated continuum data, and recombination lines are also searched towards these regions. In this talk I will present a catalogue of recombination lines and discuss the methods we used to generate it. The statistical correlation between the line parameters will be discussed in relation to the physical properties of HII regions. [Advisors: Prof. Karl Menten, Dr. Andreas Brunthaler, Dr. Friedrich Wyrowski; Second evaluator: Dr. Maria Massi]

	Lunch Colloquium
Jens Erler	ORATED

AIfA

The Sunyaev-Zel’dovich (SZ) Effect is a spectral distortion of the cosmic microwave background (CMB) caused by inverse Compton scattering of CMB photons by free electrons in a hot plasma such as the intracluster medium (ICM) found in clusters of galaxies. Its signal is proportional to the line of sight integral of the thermal gas pressure and not dimmed with redshift. Due to the high temperatures of several keV found in the ICM, relativistic effects are expected to distort the SZE spectrum, which allows to measure the temperature of the scattering gas. These relativistic corrections are well known in theory, but have only recently been observed. In my talk, I will present a stacking analysis of a large sample of galaxy clusters with data from the Planck mission. With its nine frequency channels, Planck allows to probe the entire spectrum of the SZE, making it an ideal instrument for its study. Furthermore, I will provide an outlook on future studies of the SZE with the recently granted CCAT-prime telescope.

	Master Colloquium
Richa Sharma	ORATED

MPIfR

X-ray binaries with radio emitting jets are called microquasars. The radio emission from these systems is due to synchrotron process. Short-term radio variability has been observed to be superimposed on the strong radio outburst in some microquasars. A subclass of X-ray binaries have also been detected at very high energies (TeV). Rapid TeV variability has been recently observed in blazars (a type of active galactic nuclei) and may be present in its miniature galactic counterparts called microblazars. The physical process responsible for these variability is under debate. In this context, the goal of this master thesis work is to investigate variability at radio and TeV energies in microquasars. For this purpose we study microquasar LS I +61°303 which is one of the most powerful radio and gamma-ray emitting X-ray binary. It is highly periodic at all wavelengths and show properties of a microblazar. In the first part of this thesis we use new radio data of LS I +61°303 taken from Effelsberg 100-m radio telescope at 4.85, 8.35 and 10.45 GHz. We perform timing analysis to investigate the data and detect QPO of 15 hours at all three frequencies consistent with the shock model. Out of all the six known TeV emitting X-ray binaries, this makes LS I +61°303 the second system after Cyg X-1 to exhibit radio QPO. In the second part of the thesis, we study TeV emission in LS I +61°303 and its relationship with radio emission. For this we use TeV data from literature of MAGIC and VERITAS telescopes along with GBI radio data. We find that with respect to the long-term radio modulation of LS I +61°303, the TeV emission peaks where there is minimum in the radio emission indicating towards a different origin for these energies. [First Advisor: Priv.-Doz. Dr. Maria Massi; Second Advisor: Prof. Dr. Karl M. Menten]

	Master Colloquium
Emranul Sarkar	CANCELED

MPIfR

Radio recombination lines are important diagnostic tools to understand the kinetamics of massive star forming regions. These lines are produced in the ionizing zones surrounding young massive stars and almost unambiguously identifies HII regions. Six recombination lines from H96a to H114a are studied in this work. The data came from GLOSTAR survey which is an unbiased survey of the galactic plane that uses the wideband (4GHz - 8GHz) C-band receiver from JVLA. These lines are imaged and stacked to obtain high spectral sensitivity. A source extraction code was run on the image cube to detect line emission from compact sources.Possible HII regions are identified in the associated continuum data, and recombination lines are also searched towards these regions. In this talk I will present a catalogue of recombination lines and discuss the methods we used to generate it. The statistical correlation between the line parameters will be discussed in relation to the physical properties of HII regions. [Advisors: Prof. Karl Menten, Dr. Andreas Brunthaler, Dr. Friedrich Wyrowski; Second evaluator: Dr. Maria Massi]

	Special Colloquium
Dr. Viktor Pankratius	ORATED

MIT Haystack

The process of scientific discovery is traditionally assumed to be executed by humans. This talk highlights how increasing data volumes and human cognitive limits are challenging this traditional assumption. Relevant examples are found in geoscience, planetary science, and astronomy, disciplines that are undergoing a Big Data paradigm transformation. This talk outlines how intelligent systems for computer-aided discovery can routinely complement human scientists. The pragmatics of model-based computer-aided discovery systems go beyond feature detection to answer more sophisticated questions, such as how empirical detections fit into hypothesized models and model variants. In particular, we facilitate the generation and exploration of connections between physics model candidates and empirical data sets to ease the scientist's work of placing large ensembles of detections into a theoretical context. A new discovery made with this approach has recently been confirmed in volcanology by peer-review, based on data that has been collected for over a decade. Other application examples will be outlined for groundwater phenomena on a continental scale, ionospheric phenomena, solar radio bursts, exoplanet search, and planetary landing site identification on the Moon and on Mars.

	Master Colloquium
Parichay Mazumdar	ORATED

MPIfR

Supernova Remnants (SNRs) are structures resulting from Supernovae which inject large amounts of energy, momentum and enriched ejecta into the interstellar medium (ISM). Their interaction with the ISM can cause interstellar turbulence and drive galactic outflows. Our understanding of the interaction of an SNR with a molecular cloud (MC) is limited due to the paucity of known sources and observed molecules. In this project we have carried out sub-millimeter observations of the well known SNR W28 using the APEX telescope to probe the post-shock conditions in an SNR-MC interaction region. Such a study sheds light on the molecular complexity found in these regions and helps us to understand how the SNR-MC interactions modify the physical conditions and consequently the chemistry of the ISM. In our observations, we have have found rotational lines of multiple species including CH3OH, H2CO and SO. In this talk we will have a look at the results of this study and the various methods used to constraint the physical conditions in the interaction region. [Advisor: Dr. Friedrich Wyrowski; Referees: Prof. Dr. Karl Menten and Prof. Dr. Juergen Stutzki]

	Main Colloquium
Dr Antonios Nathanail	ORATED

Institute for Theoretical Physics, Frankfurt

Gamma-ray bursts (GRBs) are violent explosions, coming from cosmological distances. They are detected in gamma-rays (also X-rays, UV, optical, radio) almost every day, and have typical durations of a few seconds to a few minutes. Some GRBs have been reported with extraordinary duration of 10⁴ sec. These are called Ultra Long GRBs. We review some observational features of GRBs.According to Blandford & Znajek (1977), the spin energy of a rotating black hole can be extracted electromagnetically, should the hole be endowed with a magnetic field supported by electric currents in a surrounding disk. We argue that this can be the case for the central engines of GRBs and we show that the lightcurves of several Long GRBs are following closely the theoretical curve of Black Hole Spin Down, thus their duration is completely characterised by the magnetic flux accumulated at the event horizon of the black hole. We further discuss how X-ray flares are produced in Long GRBs.

	Main Colloquium
Dr. Andrew Fletcher	ORATED

Newcastle University

I will review what is known about the general properties of magnetic fields in the diffuse interstellar medium. New results will then be presented, addressing questions such as: is the mean, large-scale, magnetic field preferentially connected to a particular phase of the ISM? what effect does the generation of the mean-field have on ISM structure? what are the space and time correlations of random fluctuations in the ISM? how are these correlation scales related to observables?

	Lunch Colloquium
Dr. Miriam Ramos Ceja	ORATED

AIfA

X-ray astronomy will enter a new era with the eROSITA satellite, which is expected to be launched in 2018 and to perform an all-sky survey. eROSITA will possess unprecedented sensitivity and imaging capabilities for extended emission. Since X-ray imaging is one of the most reliable methods to detect galaxy clusters, eROSITA will detect ~10^5 of such objects. The promising capabilities of eROSITA bring great expectations to constrain dark matter and dark energy models through galaxy cluster science. The instrumental features also bring new challenges, especially on object detection in X-ray images. In this sense, galaxy cluster detection is one of the most important tasks in the eROSITA science. In this talk I will show how we study the detection efficiency of galaxy clusters of the eROSITA mission. The cluster detection efficiency is investigated by means of extensive and dedicated Monte Carlo simulations and employing a state-of-the-art source detection technique.

	Main Colloquium
Dr. Baerbel Koribalski	ORATED

CASS, CSIRO

I will introduce the Australian Square Kilometre Array Pathfinder (ASKAP) which consists of 36 x 12-m dishes, each equipped with Phased-Array Feeds, operating from 0.7 to 1.8 GHz. With a field-of-view of 30 square degr ASKAP is a fast 21-cm survey machine. Early Science with 12 antennas has started and I will present first results on our target fields. I will also briefly present the "Local Volume HI Survey" (LVHIS), which was conducted with the Australia Telescope Compact Array (ATCA). The LVHIS project targets all nearby, gas-rich galaxies with vLG < 550 km/s or D < 10 Mpc that are detected in the "HI Parkes All-sky Survey" (HIPASS).

	Lunch Colloquium
Dr. Víctor M. Patiño Álvarez	ORATED

MPIfR

I present a study of different Active Galactic Nuclei, using multiwavelength data and optical spectroscopy, in order to investigate two main topics: Is there an extra component of Broad Line Region (BLR) that is not ionized by the accretion disk? Where is located the gamma-ray emission zone in blazars? I study the Baldwin Effect (BE) in 96 core-jet blazars with optical and ultraviolet spectroscopic data from a FSRQ sample obtained from the MOJAVE 2 cm survey. I present the comparison in the Baldwin Effect between radio-quiet AGN and FSRQ. I present light curves for 3C 279 and 3C 273 over a time period of six years; the longest time period used for a multiwavelength analysis since the Fermi/LAT was launched. Our multiwavelength data comprises radio to gamma-rays, with additional optical polarimetry. Based on the behavior of the gamma-ray light curve with respect to other bands, we identified three different activity periods. I present the results of the cross-correlation analysis as well as possible scenarios that explain the changes in the correlations at different epochs.

	Lunch Colloquium
Dr. Laura Spitler	ORATED

MPIfR

Fast radio bursts (FRBs) are millisecond-duration radio flashes generated in a coherent emission process, but after a decade of study the exact astrophysical origin of these bursts is still unknown. FRB 121102 is the only FRB to show repeat bursts, which has enabled an extensive follow-up campaign. Recently, the Jansky Very Large Array detected a total of 9 bursts from FRB 121102, which enabled sub-arcsecond localization of the bursting source. In addition, a persistent radio source was also detected at the position of the bursting source. Optical follow-up with the Gemini North Telescope of a faint, optical counterpart at the position of the radio sources allowed us to determine that the counterpart is a low-metalicity dwarf galaxy at a redshift of z=0.1927. Detections with the EVN improved the positional accuracy further and showed that the persistent and bursting sources are co-located to a projected distance of < 0.7 pc.

	Main Colloquium
Prof. Javier Ballesteros-Paredes	ORATED

UNAM

The so-called Larson scaling “laws” found empirically in molecular clouds (MCs) have been generally interpreted as one of the main evidences that the clouds are turbulent, that such turbulence is scale-free, and that MCs are in Virial equilibrium, implying in the collective imagination of astronomers that turbulence provides support to molecular clouds against collapse. Moreover, the origin of MC turbulence is still not properly understood, since it appears to be homogeneous and ubiquitous along the galaxy, while the sources of turbulence are mostly pointlike (stars or supernovae explosions), and turbulence is highly dissipative. In this presentation I will discuss why recent molecular cloud observations, and models of cloud formation suggest that a) Larson’s relations are the result of strong observational biases, b) how they can be replaced by a single, more general relation, which in any event, still has a large scatter, and c) why the main source of non-thermal motions in molecular clouds is a disordered, chaotic and hierarchical gravitational collapse of MCs. In other words, the supersonic, apparently turbulent but certainly chaotic motions is only a by-product of MC collapse, and it cannot be considered as the source for support of molecular clouds against collapse. This, furthermore, explains in a simple, natural way why frequently MCs appear to be in virial equilibrium. As a corollary, the scale-free nature of the motions, if exists, has a gravitational origin, rather than a turbulent one.

	Lunch Colloquium
Dr. Arnaud Belloche	ORATED

MPIfR

The search for complex organic molecules (COMs) in the interstellar medium (ISM) has revealed chemical species of ever greater complexity, in particular thanks to observations of the star-forming molecular cloud core Sgr B2(N) in the Galactic Center region. This search relies heavily on the progress made in the laboratory to record and characterize the rotational spectra of these molecules. On the observational side, the advent of ALMA with its high angular resolution and tremendous sensitivity has allowed us to reduce the spectral confusion and detect molecules of low abundance that could not be probed by previous generations of telescopes. I will present results of the EMoCA survey conducted toward Sgr B2(N) with ALMA. The main goal of this spectral line survey is to decipher the molecular content of Sgr B2(N) in order to test the predictions of astrochemical numerical simulations and gain insight into the chemical processes at work in the ISM. I will in particular report on the tentative detection of N-methylformamide, on deuterated COMs, and on the detection of a branched alkyl molecule in the ISM. The latter detection has unveiled a new domain in the structures available to the chemistry of star-forming regions and established a further connection to the COMs found in meteorites.

	Main Colloquium
Dr. Silvia Spezzano	ORATED

MPE

Starless cores represent the initial conditions of star formation and they are the ideal laboratories to study physical and chemical processes away from the complications due to protostellar feedback. We have recently compared the spatial distribution of cyclopropenylidene, c-C3H2, and methanol in L1544 and underlined a different distribution among C-bearing species within the core. I will discuss the chemical differentiation in L1544 by using the maps of over 25 molecular tracers. I will also present the laboratory facilities at the Center for Astrochemical Studies at MPE, and highlight some recent results.

	Lunch Colloquium
Dr. Yurii Pidopryhora	ORATED

AIfA

A set of diffuse interstellar clouds in the inner Galaxy has been observed at an angular resolution of ~1 arcmin combining data from the NRAO Very Large Array and the Green Bank Telescope. These are the diffuse neutral HI clouds that may constitute a considerable fraction of the interstellar medium (ISM). At the estimated distance of the clouds, the linear resolution ranges from ~1.9 to ~2.8 pc. These clouds have been chosen to be outside of the Galactic plane in order not to be confused with unrelated emission, and to lie near the tangent points in the inner Galaxy so that their distances can be quantified. But in general they belong to a widespread and ubiquitous Galactic population. Their locations are at 2.3 < R < 6.0 kpc from the Galactic Center and -1000 < z < +610 pc from the Galactic plane. Peak HI column densities lie in the range N_HI = 0.8--2.9 10^20 cm^-2. Cloud diameters vary between about 10 and 100 pc, and their HI mass spans the range from less than a hundred to a few thousands solar masses. The clouds hardly show any morphological consistency, except that their shapes are highly irregular. One cloud may lie within the hot wind bubble around the nucleus of the Galaxy, and some clouds show evidence of two distinct thermal phases as would be expected from equilibrium models of the ISM. High-resolution study of these clouds finally allows us to uncover interesting hints about their origin and dynamics.

	Special Colloquium
Laura Driessen	ORATED

University of Amsterdam

The Crab pulsar is a bright pulsar with interesting features such as giant pulses, glitches and anomalous scattering. We observed the Crab at 350MHz over two years with the Westerbork Synthesis Radio Telescope to invesigate a period of anomalous scattering that occured from late 2012 to early 2013. During this period an extra feature on the Crab, called an echo, was observed. The echo varies on short timescales and is thought to be caused by scattering close to the pulsar. I will discuss modelling the Crab pulse profile and our investigation of the echo.

	Special Colloquium
Dr. Enrique Vázquez-Semadeni	ORATED

Institute of Radioastronomy and Astrophysics UNAM Mexico

I will discuss the process of molecular cloud (MC) evolution, from their formation trhough their destruction by stellar feedback. For Solar Neighborhood conditions, MCs originate from compressive motions in the warm medium, which produce cold, dense, and turbulent atomic clouds. These clouds can quickly become strongly Jeans unstable as they incorporate material by the compression, because of their low temperature and high density. Global collapse sets in, and proceeds hierarchically: the small-scale, large-amplitude (SS) density fluctuations have shorter free-fall times than the large-scale, small amplitude (LS) ones. The LS collapses culminate a few Myr later than the SSLA ones and consist of filamentary flows that accrete onto massive central clumps. The filaments produced by this process are consistent with the observed properties of observed MC filaments. The SS collapses consist of clumps that are embedded in the filaments and are falling onto the large-scale collapse centers. The stars formed in the early, small-scale collapses share the infall motion of their parent clumps. Thus, the filaments feed both gaseous and stellar material to the massive central clump. The hierarchical collapse of the cloud leads to a hierarchical structure of the forming cluster, which naturally reproduces the observed age and mass segregation of young clusters. The global collapse of the clouds implies that their star formation rate (SFR) increases with time. Eventually, massive stars begin to form, which then begin to erode the cloud and reduce its SFR. A simple model for the collapse of MCs describes the evolution of the clouds' SFR, and explains the average cloud star formation efficiency and its observed scatter, as well as the observed age histograms of YSOs in young stellar clusters.

	Main Colloquium
Prof. Naomi McClure-Griffiths	ORATED

Australian National University

Galaxies are not closed box systems. Their evolution is impacted both by gas lost from the disk via large-scale outflows and gas accreted via various processes of inflow. Many simulations of galaxy formation and evolution have highlighted the importance of feedback in reproducing the observable Universe. Galactic winds are the dominant form of galaxy-scale feedback observed in the nearby and high-redshift Universe. Often emanating from the nuclei of massive galaxies, Galactic winds can circulate hot, enriched gas within a galaxy’s halo and out of its gravitational potential to enrich the surrounding intergalactic medium. And while we know these effects are be on-going, examples where we can observe them in detail are limited. The nuclear wind of the Milky Way provides one of the closest laboratories for Galactic winds in a non-starburst galaxy. The Milky Way’s wind has been the topic of great scrutiny in the past 5 years following the discovery of the Fermi Bubbles, showing that the highly energetic wind extends to ~8 kpc. Recently we have found evidence in 21cm HI emission for voids several kpc in size centered approximately on the Galactic center, both above and below the Galactic plane. These appear to map the boundaries of the Galactic nuclear wind, and anti-correlate with the Fermi Bubbles. In this talk I will describe how atomic hydrogen emission data on the Galactic Centre is helping us to probe the outflow of the Milky Way’s nuclear wind. While gas is constantly lost from the Galaxy via the nuclear wind and other Galactic winds, gas must also accrete onto the Milky Way to help the galaxy maintain its star formation rate. I will discuss new insights into the nature of gas in the halo and what role it might play in gas inflow.

	Special Colloquium
Dr. Alex Lazarian	ORATED

University of Wisconsin Madison

I shall discuss the new ways of tracing magnetic fields using synchrotron intensity fluctuations and show how these techniques can be used to find both the intensity of magnetic field perpendicular to the line of sight and the parallel to the line of sight component of magnetic field. I shall also discuss the complementary ways of using spectroscopic information for similar studies and the synergy of these techniques. If time permits, I shall outline new ways of using synchroton data to study compressible and incompressible components of interstellar turbulence.

	Lunch Colloquium
Dr. Rebecca Azulay	ORATED

MPIfR

We present a study of the radio emission and kinematics of a sample of stars belonging to the AB Doradus moving group through VLA and VLBI observations at frequencies of 5 and 8.4 GHz. The main aim of our study is to obtain precise estimates of the dynamical mass of young, low-mass stars, which in combination with photometric measurements provide precise benchmarks for calibrating pre-main-sequence (PMS) stellar evolutionary models. Calibration of PMS models appears essential as they are widely used to predict the masses of low mass objects as brown dwarfs and planets. Previous studies show that model predictions are in disagreement with experimental results, underpredicting the dynamical masses by 10-30%, for masses below 1.2 solar masses. Among the stars included in our study, we emphasize the results obtained in two of them: AB Dor B and HD 160934.

	Main Colloquium
Dr. Jane Arthur	ORATED

Institute of Radioastronomy and Astrophysics UNAM Mexico

I discuss developments in the modeling of the dynamics of HII regions and the use of statistical tools to make meaningful comparisons with observations. In particular, I will describe recent studies of the scale dependence of turbulence inside real and simulated HII regions in which statistical methods were applied to optical emission-line spectroscopy. The reliability of statistical methods such as structure functions and velocity channel analysis can be tested using numerical simulations and I show that only VCA can successfully recover the power-law index of the underlying velocity power spectrum of evolving HII regions. Applied to real, high-resolution, spectroscopic observations of the Orion Nebula, the velocity power spectrum turns out to be consistent with Kolmogorov theory, with a driving scale comparable to the autocorrelation length of dense cores in the surrounding Orion molecular filament. Moreover, photoevaporation flows from globules and filaments in the Orion Nebula and subsonic turbulence in the photoionized gas are found to contribute in equal measure to the observed fluctuations in the ionized density. Finally, comparison of the observational results with those from numerical simulations implies that the photoionized gas is confined to a thick shell, which is consistent with the inner region being evacuated by the action of stellar winds.

	Special Colloquium
Dr. Guang-Xing Li	ORATED

USM

Observations of gas-rich galaxies have found that molecular gas and star formation concentrates in massive, kpc-scaled giant clumps. The formation of these clumps is still a mystery. I will propose a theory where the fragmentation of a galactic disk into such clumps is driven by the collisions between molecular clouds.

	Lunch Colloquium
Dr. Chiara Mingarelli	ORATED

MPIfR

Galaxy mergers are a standard aspect of galaxy formation and evolution, and most (likely all) large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes should in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz to microhertz regime. An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in the nanohertz band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent limits which have emerged from international efforts to constrain astrophysical phenomena at the heart of supermassive black hole mergers.

	Promotionskolloquium
Denise Keller	ORATED

MPIfR

Modern radio interferometers allow the imaging of spectral line emission over a wide range of frequencies with high angular resolution. We present a detailed empirical examination and description of the molecules in the circumstellar envelope (CSE) of the archetypical evolved carbon-rich star IRC+10216 between 18 and 40 GHz obtained with the Karl G. Jansky Very Large Array (VLA). The molecular emission in the radio regime at a few arc second angular resolution has been fairly unexplored for this star. The data greatly improve our understanding of the formation and shaping of the observed CSE morphology and the inherent chemistry in the cool (10-500 K) outer CSE. Most of the detected species are carbon-bearing molecules and are distributed in hollow spheres around the star with shells, arcs, and clumps in the substructure. We focus on the cyanopolyynes and carbon chains that trace the UV-photon induced chemistry. With a new automatized procedure, we perform a detailed spatio-kinematical study of the images of the molecular line transitions. We qualitatively compare the VLA observations to state-of-the-art chemical models. Overall, we find a good correspondence between the azimuthally averaged data and the models. Our analysis emphasizes the sensitivity of the probed molecules to UV radiation. It is mandatory for future chemical models to consider the complex substructure of the circumstellar medium, particularly the density-enhancements, and the subsequent UV shielding and penetration, to more thoroughly understand the physical and chemical structure around AGB stars. This will lead to a better knowledge on the production of complex carbon-bearing molecules in the Universe. [Referees: Prof. Dr. Karl M. Menten (MPIfR), Prof. Dr. Norbert Langer (AIfA), Prof. Dr. Stephan Schlemmer (Physikalisches Institut, Uni Köln), Prof. Dr. Diana Imhof (Pharmazeutisches Institut)]

	SFB Colloquium
Dr. Anaëlle Maury	ORATED

CEA Saclay

Class 0 protostars are the first (proto)stellar objects, observed only t<0.1 Myr after their formation, while most of the mass is still in the form of a dense core/envelope collapsing onto the central protostellar embryo. The Class 0 phase is also the main accretion phase, during which most of the final stellar mass is accreted onto the central protostellar object. Therefore, during the Class 0 phase, the accreted circumstellar envelope must redistribute most of its initial angular momentum outward, or centrifugal forces will prevent further accretion onto the protostar: how this is done exactly is still an open question, known as the long-standing angular momentum problem for star formation. Several key questions about the typical outcome of protostellar collapse, tied to this angular momentum problem, still remain open, such as the initial conditions for building protostellar disks and binary systems, which are routinely observed at the later stages of evolution. Solving not only these questions, but also understanding the typical outcome of protostellar formation, and therefore the formation of most stars, ultimately depends on characterizing the forces at work to regulate the angular momentum content and evolution during the Class 0 phase. I will present new insights on the possible solutions to the angular momentum problem, obtained thanks to the detailed analysis of millimeter observations of protostellar envelopes probing the envelope density, structure and kinematics from the small scales (50 au) to large scales (5000 au) obtained mostly with the Plateau de Bure interferometer (PdBI) and the IRAM 30m telescope in the framework of the CALYPSO (Continuum and Line in Young Protostellar Objects, see http://irfu.cea.fr/Projets/Calypso/) program. While the presence of large accretion disks is well documented in more evolved Class I objects and T Tauri stars, I will show that the detection of the large (r >100au) Keplerian disks expected from conservation of angular momentum during protostellar collapse, have remained elusive around Class 0 protostars. I will also present recent SMA and ALMA observations of magnetic fields in Class 0 protostars at scales 20-10000 au, arguing that the small disk sizes observed during the main accretion phase are in favor of a magnetically-regulated collapse scenario for the formation of most low-mass stars.

	Lunch Colloquium
Silvia Leurini	ORATED

MPIfR Bonn

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

	Lunch Colloquium
Dr. Gundolf Wieching	ORATED

MPIfR

The MeerKAT observatory is located in the South African Karoo area. The very remote location as well as geographic conditions results in an excellent radio astronomical site only affected minimally by RFI. A radio-quiet area around the MeerKAT site with a size larger than that of the Netherlands has been protected by a government act as an astronomy reserve. The observatory is composed of two main units, the 64 13.5m offset Gregorian antennas (aka receptors) and the main processing building. The antennas are distributed on a flat plateau within an 8km diameter. Each of the 64 MeerKAT antennas will be equipped with one receiver MPIfR S-Band Rx frontend. The receiver frontend includes all components to collect, amplify and digitize the signal. The frontend transmits the digitized signals via the MeerKAT communication network, using standard Ethernet, to the backend section of MeerKAT at the processing building. The talk will outline the S-Band MeerKAT Rx design, present an update on the instrumentational developments and the first prototype tests.