Special Colloquium
Dr. Bryan Butler	ORATED

NRAO, Socorro, New Mexico, USA

Building on the remarkable success of the VLA, VLBA, and ALMA, NRAO is planning a large collecting area interferometer which will replace the VLA and VLBA - the next generation Very Large Array (ngVLA). For many of the same reasons that the VLA was constructed where it was (fraction of sky visible, quality of site, accessibility, etc.), the core and bulk of the collecting area of the ngVLA will be on the Plains of San Agustin, near where the center of the current VLA is. The ngVLA will have more than 10 times the sensitivity and spatial resolution of the VLA and ALMA, operating at frequencies from 1.2-116 GHz. The ngVLA will be optimized for observations at wavelengths between those of ALMA at mm-submm wavelengths, and the future SKA-1 at dm-m wavelengths, to be complementary to those instruments. The ngVLA will be transformative, with exquisite sensitivity to thermal line and continuum emission down to milliarcsecond resolution. The science goals are broad (a science book with more than 90 chapters and 285 unique authors has been written), but focus on: formation of planetary systems on terrestrial planet scales, including astrochemistry; characterization of galaxy structure and evolution; using pulsars in the Galactic center to test fundamental theories of gravity; and understanding the formation and evolution of stellar and supermassive black holes in the era of multi-messenger astronomy.

	Master Colloquium
Mahathi Chavali	ORATED

Max-Planck-Institut für Radioastronomie

Water is a key molecule to model the physics and chemistry of star formation. It is also the main constituent of icy grain mantles in the universe. We studied HDO and H2O transitions observed by the APEX telescope in the ATLASGAL TOP100 sample containing 110 clumps representing all evolutionary stages of high-mass star formation. We studied the ratio of HDO/H2O as the level of deuterium fractionation of a molecule is a good tracer of its formation process. H2-18O, an isotopologue of water is observed as a tracer for water, as water is difficult to observe from the ground. Water deuterium fractionation has been studied before, but not in such a large sample and range of evolutionary stages. The analysis is complicated by line blending with transitions from other molecules. We analysed these observations using the 1D radiative transfer code RATRAN to obtain the fractional abundances of HDO and H2O. Our studies show that the water deuterium fractionation values are about two orders of magnitude larger in star forming regions, compared to the elemental D/H ratio. [Referees: Prof. Dr. Karl Menten, Prof. Dr. Frank Bigiel]

	Special Colloquium
Prof. Adam Leroy	ORATED

Ohio State University, USA

I will present PHANGS-ALMA a multi-cycle ALMA survey of 90 nearby galaxies that offered our first real cloud-scale survey of molecular gas in galaxies. Stars form in giant molecular clouds, which are dense, cold condensations of gas that in many ways act as the engines of galaxy evolution. The demographics, evolution, and physical state of these clouds relate directly to how star formation proceeds, feedback operates, and galaxies grow. Until recently, however, we lacked any large survey that resolved the gas in galaxies into individual clouds. Leveraging ALMA's amazing combination of resolution, sensitivity, and mapping speed, PHANGS-ALMA mapped the CO 2-1 emission, our basic tracer of molecular gas in galaxies, at 1" = 50-150 pc resolution scales across essentially all accessible very nearby star-forming galaxies. On its own, PHANGS-ALMA resolves the molecular gas across whole galaxies into individual star-forming molecular clouds, giving access to the demographics and properties of tens of thousands of molecular clouds across a representative set of z=0 galaxies. When paired with large programs on VLT/MUSE, HST, ALMA mapping of high critical density lines, and soon JWST and MeerKAT, PHANGS offers a pan-chromatic view that breaks a representative sample of galaxies into individual star forming regions for the first time. I will give an overview of the motivation and execution of the survey, describe the data and products available to the community, and then highlight results on a few key topics - demographics, life cycles, and star formation properties of clouds - from the PHANGS team.

	Main Colloquium
Dr. Shane O'Sullivan	ORATED

Dublin City University

Radio galaxies can be observed throughout the majority of the history of the Universe and are thus excellent beacons for measuring the properties of the cosmic web and their evolution with cosmic time. Here I will highlight recent results from the ongoing LOFAR Two-metre Sky Survey (LoTSS), with a focus on the linear polarization and Faraday rotation measure (RM) data. The exceptional RM precision of LoTSS (< 0.1 rad/m2), in addition to unrivalled ancillary information such as the host galaxy redshift, has facilitated several new discoveries. For example, our recent detection of the RM signature from cosmic web filaments shows how LoTSS is transforming our understanding of cosmic magnetic fields, and providing a new way to study the properties of filaments and voids of the cosmic web in general.

	Special Colloquium
Various Panelists	ORATED

Event Horizon Telescope Collaboration

The Event Horizon Telescope (EHT) presented on May 12, 2022 the results from the observations of Sagittarius A* (Sgr A* ), the Galactic center source associated with a supermassive black hole. Those are based on observations conducted in 2017 with very-long-baseline interferometry operating at a wavelength of 1.3 mm. These results support an image dominated by a bright, thick ring with a diameter of about 52 microarcseconds, consistent with the appearance of a Kerr black hole with mass of 4 million solar masses. These results provide direct evidence for the presence of a supermassive black hole at the centre of the Milky Way. Details on these results will be provided in a series of short talks by MPIfR affiliated astronomers who are part of the EHT team, spanning over two hours including discussion: introduction by Anton Zensus and Karl Menten; followed by short presentations by Alan Roy, Michael Janssen, Eduardo Ros, Gunther Witzel, Christian M. Fromm, and Michael Kramer, concluding with a final discussion.

	Special Colloquium
Dr. Chiara Spiniello	ORATED

University of Oxford (UK)

Massive early-type galaxies (ETGs) are believed to form through a two-phase process: an intense and fast star formation episode creates red, compact, and massive objects (“red nuggets”), and then a second phase, dominated by mergers and gas inflows, causes structural evolution and size growth. Luckily, since merging is believed to be stochastic, a small fraction of red nuggets survives intact until the present-day Universe, without experiencing any further interaction: the so-called Relic Galaxies. These very old Ultra Compact Massive Galaxies (UCMGs) are made of “in situ only“ pristine stellar populations, and as such they provide a unique opportunity to track the formation of this specific galaxy stellar component, which is mixed with the accreted one in normal massive ETGs. In this talk I will first introduce our effort in obtaining a complete census of UCMGs at z between 0.1 and 0.5 from the Kilo Degree Survey, and then introduce the on-going INvestigating Stellar Population In RElics (INSPIRE) project which aims at building the first statistically large sample of confirmed relics. I will give few details on the target selection, observation, data analysis, strategies and results obtained in the INSPIRE Data Release 1, based on 19 systems for which observations were completed in 2020. In particular, I will present the kinematics and stellar population results and the relic confirmation for the biggest sample of spectroscopically confirmed relic galaxies currently available beyond the local universe. I will finally introduce some future perspectives and goals of INSPIRE, highlighting how relics can be used as powerful tools to study the early phases of massive galaxies formation.

	Special Colloquium
PD Dr. Silke Britzen	ORATED

MPIfR

Die Event-Horizon-Teleskop- (EHT) Kollaboration hat am 12. Mai das erste Bild vom Schatten des Schwarzen Lochs im Zentrum unserer Galaxie veröffentlicht. Es ist das erste Bild von Sgr A* , aber bereits das zweite Bild eines supermassereichen Schwarzen Lochs (nach M87* ). Mit einem Netzwerk von acht Radioteleskopen, das fast die Größe der Erde erreicht, gelang ein Bild, an dem auch viele Kollegen aus dem MPIfR lange gearbeitet haben. Ich berichte über die Entstehung dieses Bildes, die Unterschiede zwischen Sgr A* und M87* und die Bedeutung der Aufnahmen für die Erforschung dieser kosmischen Schwerkraftfallen. [Dieser Vortrag richtet sich an alle Mitarbeiter des Instituts]

	Special Colloquium
Dr. David Martı́nez Delgado	ORATED

Instituto de Astrofı́sica de Andalucı́a (CSIC), Spain

Within the hierarchical framework for galaxy formation, merging and tidal interactions are expected to shape large galaxies up to the present day. While major mergers are quite rare at present, minor mergers and satellite disruptions - that result in stellar streams - should be common, and are indeed seen in the stellar halos of the Milky Way and the Andromeda galaxy. In the last years, the Stellar Stream Legacy Survey (PI. Martinez-Delgado) has exploited available deep imaging of some nearby spiral galaxies with the ultimate aim of estimating the frequency, morphology and stellar luminosity/mass distribution of these structures in the local Universe. In this talk, I will present the current results of our systematic survey of stellar streams together with some recent follow-up observations (e.g. Megara, Subaru) and N-body modelling of the most striking streams. Finally, I will discuss what we can learn about galaxy formation from the results of this survey, including the comparison with the available L-CDM cosmological simulations.

	Main Colloquium
Prof. Simon Stellmer	ORATED

Physikalisches Institut der Universität Bonn

Astronomy and low-energy quantum physics experiments might seem to be located at opposite ends of the spectrum of physics research, but there are surprisingly many connections. I will elaborate on two of such topics. Firstly, I will present searches for beyond-standard-model physics based on precision spectroscopy. Secondly, I will advertise a new initiative to determine the Earth orientation parameters through a novel type of ring laser gyroscope.

	Special Colloquium
Dr. Tomás Cassanelli	ORATED

Departamento Ingeniería Eléctrica, Universidad de Chile, Santiago, Chile

The sensitivity of a radio telescope is of significant scientific interest. By increasing the sensitivity (or increasing the aperture efficiency) we are able to reduce errors in the telescope's main beam, and hence detect fainter sources. Out-of-focus (OOF) holography is a method to determine errors in the aperture plane of a radio telescope. In contrast to traditional holography, OOF can be applied without extra equipment and using common astronomical sources and receivers. By correcting aperture errors we are improving the surface accuracy, and effectively improving the aperture efficiency. In this talk I will describe the method, the developed software (pyoof), the observations, and how it is applied to the Effelsberg telescope. Results from multi-year observational campaigns will also be discussed, in an effort to model repeatable sources of deformation over the 100-m collector and improve its surface efficiency.

	SFB Colloquium
Prof. Brett McGuire	ORATED

Massachusetts Institute of Technology, Cambridge, USA

Polycyclic Aromatic Hydrocarbons (PAHs) have been implicated as a large reservoir of reactive carbon in the interstellar medium since the 1980s. PAHs have been widely attributed as the carriers of the unidentified infrared bands where their aggregate vibrational emission spectra are extremely well matched to the observed line signals. Only in the last year have individual PAHs been detected in the ISM for the first time, however, allowing us to begin to investigate the detailed chemical pathways for the formation and destruction of these molecules. In this talk, I will discuss our detections of PAH molecules via their rotational transitions using Green Bank Telescope observations of TMC-1 from the GOTHAM collaboration. I will discuss the efforts to model the chemistry of these PAHs, the necessity of complementary laboratory kinetics work, our application of novel machine learning approaches to exploring the chemical inventory in TMC-1, and finally the benefits of unbiased reaction screening studies in the laboratory with Microwave Spectral Taxonomy.

	Main Colloquium
Dr. Nami Sakai	ORATED

RIKEN Cluster for Pioneering Research, Saitama, Japan

Star and planet formation is one of the most fundamental structure-formation processes in the Universe. Physical processes of star and planet formation have widely been investigated as one of the major targets of astronomy and astrophysics by observations in all the wavelength region from radio to X-ray during the last few decades. Although a rough outline of these processes has been presented, there remain many unknowns and missing links. On the other hand, star and planet formation is a process where interstellar matter is evolved into planets. Hence exploring chemical evolution is of fundamental importance in understanding the origin of the Solar system, and eventually the origin of life on the Earth.  We have thus started to study the chemical evolution by collaborating with people in molecular science field. Such chemical approach also tells us novel information on physical processes of star and planet formation. In this talk, I will introduce efforts on such studies.

	Special Colloquium
Dr. Pierre Cox	ORATED

Institut d'Astrophysique de Paris, France

The Herschel surveys have enabled the detection of numerous dusty luminous sub-millimeter galaxies (SMGs) in the early universe. Follow-up observations of these sources are essential to determine their nature and the physical properties of their interstellar medium; reliable measurements of their redshifts are therefore crucial to explore the molecular and atomic gas of these objects. I will here present the results of a Large Program, z-GAL, using NOEMA, aimed at a comprehensive 3 and 2-mm spectroscopic redshift survey of a large (~140 sources) sample of the brightest (S500microm>80 mJy) SMGs selected from the Herschel H-ATLAS and HerMES surveys, which probe the peak of cosmic evolution (2

	Main Colloquium
Prof. Dominik Riechers	ORATED

Universität zu Köln

Recent years have seen great advances in studies of galaxy evolution and the early Universe due to substantial upgrades in our observational capabilities, coupled with ever more complex simulations of star, galaxy, and cosmic structure formation. I will highlight a range of new investigations of the cosmic baryon cycle coupling galaxies to their environments through their gas reservoirs, gas accretion, and outflows as a result of feedback processes driven by newly formed massive stars and active galactic nuclei. These properties evolve through cosmic history due to changes in the properties of "typical" galaxies and those undergoing their most intense phases of activity, but also due to changes in the environments resulting from the formation ever more pronounced cosmic structures and the cooling of the Universe due to cosmic expansion. I will introduce a new method to constrain the latter through direct line absorption against the cosmic microwave background, and promising new observational methods to constrain the former through large-scale line intensity mapping surveys of the early Universe, all the way back to cosmic reionization. Due to the rapid progress in observational, theoretical, and laboratory astronomy over the past decade, as well as new trends in astronomical instrumentation and facilities like CCAT-prime, ALMA 2030, NOEMA, the SKA and the ngVLA, we will have the tools to usher in a new phase in our understanding of the evolving cosmos back to its infancy stages in the coming decade.

	Special Colloquium
Dr. Carolina Casadio	ORATED

Institute of Astrophysics - FORTH, Heraklion, Greece

Projects aimed at characterising dark matter properties make use of very different approaches. One such approach is to look for strong gravitational lens systems. Gravitational lensed images with angular separation on milli-arcsecond scales probe gravitational lens systems where the lens is a compact object with mass in the range 10^6-10^9 solar masses, i.e. a supermassive compact object (SMCO). This mass range is particularly critical for the widely accepted cosmological model, which predicts many more DM halos on sub-galactic scales (< ~ 10^11 solar masses) than currently observed. The most direct way to explore these small angular scales is through the high-resolution of radio Very Long Baseline Interferometry (VLBI). We perform a pilot search, using the Astrogeo VLBI FITS image database and collecting multi-frequency, multi-epoch VLBI data of 13828 individual sources. We identified 40 milli-lens candidates, which have been followed-up with multi-frequency European VLBI Network (EVN) observations. Performing a similar search in a complete sample of ~ 5000 sources would allow us to constraint the abundance of SMCO in the Universe with more than an order of magnitude better precision than in previous studies, and to ultimately reject many currently viable DM models.

	Special Colloquium
Prof. Dr. Yuri Y. Kovalev	ORATED

Astro Space Center of Lebedev Phys. Inst. and Moscow Inst. of Phys. and Technology, Moscow, Russia

In this talk I will discuss recent developments in AGN studies on parsec and sub-parsec scales made with ground and Space VLBI as well with multi-band and multi-messenger observations. These include the extreme brightness temperature puzzle of RadioAstron measurements, the VLBI-Gaia view on the AGN disk-jet system, and the mounting observational indications for the blazar-neutrino connection. I will conclude the talk by outlining several exciting opportunities for centimeter and millimeter single-dish and VLBI experiments which will be playing a key role in the coming new era of multi-messenger astronomy.

	Main Colloquium
Dr. Guilaine Lagache	ORATED

Laboratoire d'Astrophysique de Marseille, Frankreich

CONCERTO is a new instrument that has just been successfully installed in the Cassegrain Cabin of the APEX telescope. It is a spectrometer with an instantaneous field of view exceeding 260 square arcminute and a spectral resolution up to 1.5 GHz. It covers the frequency band 130-310 GHz. The main scientific aim of CONCERTO is to map in 3D the fluctuations of the [CII] line intensity in the reionisation and post-reionisation epoch (z>5). This technique, known as intensity mapping, will allow us to address questions about the contribution of the dust-enshrouded star formation at z > 5, the history of metal enrichment, and the role of star-forming galaxies in shaping cosmic reionization. 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 (via the thermal and kinetic SZ effect), the follow-up of cosmological deep surveys, the observation of local galaxies, and the study of Galactic star-forming clouds. CONCERTO will also observe the CO intensity fluctuations arising from 0.3

	Main Colloquium
Dr. Eda Gjergo	ORATED

Wuhan University, China

The astrophysical sites which dominate the production of r-process elements have been a matter of contention for decades. The event GW170817/AT2017gfo, with the confirmed observation of the neutron-capture element strontium, originally raised hopes that neutron star mergers (NSM) could be a leading contributor to the production of heavy elements. However, galactic chemical evolution (GCE) models which take into account the rates of NSM events show that the onset of NSM occurs too late in the enrichment history to explain the abundance patterns of extremely metal poor stars. Among the other candidates is the small fraction of core-collapse supernovae whose progenitor star rotates sufficiently fast and creates magneto-hydrodynamic jets (MHDJ) capable of yielding r-process enrichment. It is possible that the rarity of such events may be offset by the larger rates and mass ejecta. After an introduction on GCE modeling, I will present results which include novel yield tabulations of neutron-capture events. I will explore the dependence of neutron-capture element abundances on theoretical NSM rates, as well as on future GW missions. We investigate some variation of parameters in single-zone GCE models for both the Milky Way and dwarf galaxies. On a s-process production baseline by AGB and core-collapse SNe, we estimate which conditions favor one r-process enrichment scenario over the other.

	Main Colloquium
Prof. Karl Mannheim	ORATED

Institut für Theoretische Physik und Astrophysik, Universität Würzburg

The plasma composition of jets ejected from accreting black holes in active galactic nuclei remains uncertain up to the present day. Inevitably, photon-photon pair production must lead to an excess of electron-positron pairs that remains unaccounted for in conventional single-fluid GRMHD simulations. Photon-photon pair production occurs in the virial plasma close to the ergosphere. Prolific pair production also results from particle acceleration throughout the jet. Multi-TeV gamma rays and the tentative associations of blazars with high-energy neutrinos and of radio galaxies with ultra-high energy cosmic rays require efficient acceleration of particles to ultra-high energies. Considerable efforts to encompass the kinetic processes responsible for the transport and acceleration of relativistic particles are currently undertaken to better understand how they shape the morphology and spectral energy distributions of jets. Studies of variability are key to understand the anisotropies associated with the acceleration processes and the stochastic nature of energy dissipation. Dissipation by kinetic processes resembles an exponential version of Ohmic dissipation in an electric wire.

	Main Colloquium
Prof. Sara Buson	CANCELED

Institut für Theoretische Physik und Astrophysik, Universität Würzburg

TBD

	Main Colloquium
Prof. Thiem Hoang	ORATED

Korea Astronomy and Space Science Institute, Daejeon, Republic of Korea

Dust is ubiquitous in the Universe and plays an important role in astrophysics. Dust grains are the building blocks of planets and catalytic surfaces for the formation of water and complex molecules. Dust polarization induced by the alignment of dust grains with the magnetic field is a powerful technique to observe cosmic magnetic fields and constrain dust properties. Dust grain size distribution determines star extinction and is a fundamental property for describing radiation pressure feedback from stars, supernova, and active galactic nuclei. In this talk, I shall show that grain’s suprathermal rotation plays a crucial role in dust astrophysics, determining grain alignment and affecting grain size distribution and surface chemistry. I shall first review the main physical mechanisms for grain alignment, including radiative torques and mechanical torques. I will then discuss the physics of rotational disruption of dust grains due to radiative torques, which implies the change of the dust properties with the local radiation field and density from the local medium to high-redshift galaxies. I will also discuss the new effects of suprathermal rotation on surface chemistry, radiation pressure feedback, and grain growth. Finally, I shall discuss a synergy of synthetic modeling with observations to test the new dust physical effects, probe dust properties, and measure magnetic fields in star-forming regions.

	Main Colloquium
Dr. Laura Kreidberg	ORATED

Max-Planck-Institut für Astronomie, Heidelberg

The past 25 years have revealed a diversity of exoplanets far beyond what was imagined from the limited sample in the Solar System. With new and upcoming observing facilities and a rapidly growing number of nearby planets, we are poised to bring this diversity into focus, with detailed follow-up characterization of the planets’ atmospheres. In this talk, I will discuss two frontier topics in exoplanet atmosphere studies: (1) what can we learn about giant planets' origins from their present-day atmospheres? and (2) what can we learn about habitability from “Earth cousins”, planets that are a little bigger or a little hotter than the Earth? Finally, I will conclude with my outlook on the search for biosignatures in the atmospheres of potentially inhabited planets.

	Main Colloquium
Prof. Anna Watts	ORATED

Astronomical Institute Anton Pannekoek, University of Amsterdam

NICER, the Neutron Star Interior Composition Explorer, is an X-ray telescope that was installed on the International Space Station in 2017. Its mission is to study the nature of the densest matter in the Universe, found in the cores of neutron stars. NICER uses Pulse Profile Modeling, a technique that exploits relativistic effects on X-rays emitted from the hot magnetic polar caps of millisecond pulsars. The technique also lets us map the hot emitting regions, which form as magnetospheric particles slam into the stellar surface. I will present NICER's latest results - including a measurement of the radius of the highest mass pulsar known - and discuss the implications for our understanding of ultradense matter, pulsar emission, and stellar magnetic fields. I will also look ahead to the next generation of X-ray telescopes that will exploit the Pulse Profile Modelling technique.

	Promotionskolloquium
Weiwei Chen	ORATED

Max-Planck-Institut für Radioastronomie

Fast transients are usually the products of rapid and enormous energy releases. To study the physical nature behind them, we must know the subtle temporal structure of the signal and where precisely they come from. However, some sporadic or even one-off fast radio transients have brought challenges to the current instruments. In this presentation, I describe the general beamforming technique, withwhich efficient wide-field, high time and spatial resolution survey can be achieved. Following that, I introduce the software package: MOSAIC developed for this project to provide the solutions to the challenges that come with this technique, such as the characterization of volatile beam shapes, the generation of efficient tiling of beams and the prediction of the evolution of the tiling through time. As an evaluation, a beamformed observation with MeerKAT on 47 Tucanae using the said techniques is presented and the localization capability with multiple beams is demonstrated. The performance of this beamforming platform has been further tested in numerous observations and surveys such as TRAPUM and MGPS that have yield significant results. I also report a search for giant pulses in selected pulsars. Many models try to explain the emission mechanism behind giant pulses from pulsars, some of which invoke the re-connection events near the light cylinder. In the meantime, a population of known giant pulse emitters shares similar properties, such as strong magnetic fields near the light cylinder and high energy emission. I select a couple of pulsars with these properties as candidates and observed them using the Effelsberg 100-meter telescope. A pipeline based on Heimdall was created to search giant pulses on the data and no credible detection was found. The conclusion for the non-detection is that these pulsars do not emit giant pulses which are detectable by our observation, or the high magnetic field strength near the light cylinder may not be a sufficient condition for the occurrence of giant pulses. [Referees: Prof. Dr. Michael Kramer, Prof. Dr. Frank Bertoldi, Prof. Dr. Ian Brock, Prof. Dr. Klaus Greve]

	Main Colloquium
Dr. Izaskun Jiménez-Serra	ORATED

Centro de Astrobiología, Madrid, Spain

In the past decade, Astrochemistry has witnessed an impressive increase in the number of detections of complex organic molecules. Some of these species are of prebiotic interest such as glycolaldehyde, the simplest sugar, or amino acetonitrile, a possible precursor of glycine. Recently, we have reported the detection of several new complex organic species in the interstellar medium, such as hydroxylamine and ethanolamine, known to be intermediate species in the formation processes of ribonucleotides and phospholipids within theories for the origin of life. In this talk, I will present our recent efforts to establish whether key precursors of prebiotic systems chemistry can be found in space. I will also analyse how chemical complexity builds up in the interstellar medium thanks to observations of the complex organic content in starless/pre-stellar cores, which represent the initial conditions of Solar-system formation.

	Main Colloquium
Dr. John Tobin	ORATED

National Radio Astronomy Observatory, Charlottesville, USA

The formation of disks and multiple star systems are integral parts of the star and planet formation process. Most stellar mass must be accreted through a disk, disks are the future sites of planet formation, and disks will also give rise to companion stars. Using ALMA and the VLA, we are conducting large continuum surveys of protostars (with molecular lines toward a subset of the full sample) in the nearby Perseus and Orion star-forming regions (with 20-30 au resolution) to characterize the disk radii, disk masses, and frequency of multiplicity throughout the protostellar phase. The molecular line data enable us to measure the masses of the protostars and we are beginning to identify and characterize the formation environments of both low and intermediate mass protostars. We find clear changes in multiplicity properties with evolution that link back to their formation mechanisms, establishing a foundation from which multiplicity evolution must begin.

	Informal Colloquium
Caroline Gieser	ORATED

Max-Planck-Institut für Astronomie, Heidelberg

During high-mass star formation, fragmentation takes place on various spatial scales from giant molecular clouds down to disk scales. At the earliest evolutionary stages, high-mass protostars are still deeply embedded within their parental molecular cloud and can be studied best at high spatial resolution with interferometers at mm wavelengths. The IRAM/NOEMA large program CORE allows us to analyze the physical and chemical properties of a sample of luminous high-mass star-forming regions. The 1 mm dust continuum of the sample shows a large diversity of fragmentation properties. Using the spectral line emission, we are able to determine the physical structure (temperature and density) and molecular content of individual fragmented cores. Even though all regions are classified to harbor high-mass protostellar objects, the molecular content shows a high degree of complexity. By combining the observed core properties, we are able to estimate chemical timescales with the physical-chemical model MUSCLE. We find well-constrained density and temperature profiles in agreement with theoretical predictions. The molecular complexity in the core spectra can be explained by an age spread that is then confirmed by our physical-chemical modeling. The hot molecular cores show the greatest number of emission lines, but we also find evolved cores in which most molecules are destroyed and, thus, the spectra appear line-poor once again. Currently, we are expanding our sample with ALMA 3 mm observations of 11 additional high-mass star-forming regions at different evolutionary stages - from infrared dark clouds to ultra-compact HII regions - in order to further investigate the evolution of the physical and chemical properties on core scales.

	Main Colloquium
Dr. Evan Keane	ORATED

National University of Ireland, Galway

Neutron stars exhibit many of the most extreme phenomena ever observed. They are also the most precise astrophysical tools in existence. Fortunately they are readily observable, across the electromagnetic spectrum, from Birr to Bonn to Boolardy. In this talk I will describe what is, and is not, known about neutron stars, with particular emphasis on the inter-related topics of their evolution post-supernova and pulsar emission physics. I will describe the difficulties involved in identifying evolutionary tracks for neutron stars, and discuss some potential solutions to these. Considering the growing number of diverse observational classes within the 'neutron star zoo' I will describe how these groups are, and are not, evolutionarily linked to one another. I will also describe search strategies that might identify the most interesting undiscovered sources.

	Promotionskolloquium
Vishnu Balakrishnan	ORATED

Max-Planck-Institut für Radioastronomie

Pulsars are rapidly rotating highly magnetised neutron stars that emit beams of electromagnetic radiation from their magnetic poles. These compact objects are unique as they are one of the densest forms of matter known in the Universe. Discovering pulsars are a gateway to new and exciting science as they have a wide range of scientific applications from studies of strong-field tests of gravity, neutron star physics and cosmology being a few examples. While all pulsars have their own applications, the bulk of my talk will concentrate on the techniques involved in finding new relativistic binary pulsars particularly the yet to be detected pulsar black-hole binary (PSR-BH) which can be used to test General Relativity and alternate theories of gravity in the quasi-stationary strong-field regime. As I will describe, in my thesis work I improved on our detection sensitivity towards PSR-BH binaries by a factor of 2-2.5 that was achieved purely by changing the search algorithm. I will present the results of my comprehensive search for recycled and unrecycled PSR-BH binaries in circular orbits in the High Time Resolution Universe South Low Latitude Survey (HTRU-S lowlat) using the template-bank algorithm. I will give details about the 20 new pulsars that were found from my searches including a new millisecond pulsar J1743−24 which is a rare intermediate spin-period pulsar in a 70.7-day orbit around a light companion star. Using our non-detections of PSR-BH binaries, I will also present limits on short orbital period PSR-BH binaries near the Galactic-Plane (|b| < 3.5 deg). I will also describe a novel Machine-learning (ML) pulsar candidate classifier using Semi-Supervised Generative Adversarial Networks (SGAN) which achieved better classification performance than the standard supervised algorithms commonly used in the literature using majority unlabelled datasets. Additionally, I will also present the results of the first fully coherent GPU-based radio pulsar search pipeline that can search across all five Keplerian parameters. We compare results from my pipeline to standard time and frequency domain acceleration and jerk search pipelines currently used in the literature. I will discuss its computational feasibility and the binary parameter spaces that have opened up that were previously not accessible. [Referees: Prof. Dr. Michael Kramer, Prof. Dr. Norbert Langer, Prof. Dr. Simon Stellmer, Prof. Dr. Volkmar Gieselmann]