July 2020

09/07/20 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — ESO's Extremely Large Telescope and the future of European ground-based astronomy
Michele Cirasuolo (ESO)
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Abstract

The Extremely Large Telescope (ELT) is a revolutionary scientific facility that will allow the ESO astronomical community to address many of the most pressing unsolved questions about our Universe. The ELT with its 39-metre primary mirror will be the largest optical/near-IR telescope in the world and will open a huge discovery space.

In this presentation I will provide an overview of the ELT Programme, highlighting the latest status of the telescope and the instrumentation. I will then focus on the key science drivers: from the discovery of extrasolar planets and possibility of life, to the evolution of stars and galaxies, to Cosmology and our understanding of the Universe.

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June 2020

25/06/20 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Our Galaxy in its infancy as traced by Gaia and complementary spectroscopic surveys
Paola Di Matteo (GEPI, Observatoire de Paris)
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Abstract

Reconstructing the past of the Milky Way depends on the study of its metal-poor stars, which either have been formed in the Galaxy itself in the first billion years, or have been accreted through mergers of satellite galaxies over time. These stars are usually found in what is known as the Milky Way halo, a light — in terms of total mass —  stellar component which is usually seen to contain stars whose kinematics significantly deviates from that of the Galactic disc.

In this talk, I will discuss how it has been possible to use the astrometric and spectroscopic data delivered by Gaia and complementary surveys  to shed light on the past of our Galaxy, through the study of its halo. Besides the discovery of the possible last significant merger experienced by the Milky Way, the use of 6D phase space information and chemical abundances allowed to reconstruct the impact this merger had on the early Milky Way disc, and the time it occurred, as well as to discover that some of the most metal-poor stars in the Galaxy possibly formed in a disc.  This last finding would implyt that the dissipative collapse that led to the formation of the old Galactic disc must have been extremely fast.

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18/06/20 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — The Physics of Structure Formation
Raúl Angulo (Donostia International Physics Center)
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04/06/20 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Dark matter heats up in dwarf galaxies
Justin Read (University of Surrey)
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May 2020

28/05/20 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — The MIGHTEE Survey: Progress and Future Plans
Matt Jarvis (Oxford University)
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Abstract

The MIGHTEE large survey project is surveying four of the most well-studied extragalactic deep fields, totalling ~20 square degrees to micro-Jy sensitivity at Giga-Hertz frequencies, as well as an ultra-deep image of a single ~1 square degree MeerKAT pointing. The observations will provide radio continuum, spectral line and polarisation information. As such, MIGHTEE, along with the excellent multi-wavelength data already available in these deep fields, will allow a range of science to be achieved. Specifically, MIGHTEE is designed to significantly enhance our understanding of, (i) the evolution of AGN and star-formation activity over cosmic time, as a function of stellar mass and environment, free of dust obscuration; (ii) the evolution of neutral hydrogen in the Universe and how this neutral gas eventually turns into stars after moving through the molecular phase, and how efficiently this can fuel AGN activity; (iii) the properties of cosmic magnetic fields and how they evolve in clusters, filaments and galaxies. MIGHTEE will reach similar depth to the planned SKA all-sky survey, and thus will provide a pilot to the cosmology experiments that will be carried out by the SKA over a much larger survey volume.

In this talk, I will provide an overview of the MIGHTEE project, the current status of observations and some early science results.

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14/05/20 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Hydrodynamical simulations of galaxy formation
Volker Springel (MPA)
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07/05/20 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Our astrochemical origins
Paola Caselli (MPE)

April 2020

30/04/20 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Mapping the hot Universe: the first six months of operations of eROSITA on SRG
Andrea Merloni (MPE)
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23/04/20 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — The smallest dark matter halos
Simon White (MPA)
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16/04/20 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Testing general relativity and the massive black hole paradigm in the Galactic Center
Reinhard Genzel (MPE)
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February 2020

13/02/20 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Information field theory: from astronomical imaging to artificial intelligence
Torsten Enßlin (MPA)
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Abstract

Turning the raw data of an instrument into  high-fidelity pictures of the Universe is a central theme in astronomy. Information field theory (IFT) describes probabilistic image reconstruction from incomplete and noisy data exploiting all available information. Astronomical applications of IFT are galactic tomography, gamma- and radio- astronomical imaging, and the analysis of cosmic microwave background data. This talk introduces into the basic ideas of IFT, highlights its astronomical applications, and explains its relation with contemporary artificial intelligence.

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06/02/20 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Star-Forming GMCs Regulated by Feedback
Eve Ostriker (Princeton University)
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Abstract

Giant molecular clouds (GMCs) are the home of the most extreme conditions and the most dramatic events found in the interstellar medium (ISM). As hosts of the densest, coldest portion of the ISM’s gas, gravitational collapse is inevitable, and leads to the formation of star clusters. These young star clusters, in turn, host massive and luminous stars that profoundly alter — and ultimately destroy — their birth clouds, by a combination of photoevaporation, radiation forces on dust, and strong shocks from winds and supernovae. Because GMCs are porous, the energy injected by massive stars also escapes to power the surrounding ISM. Given the complex array of processes involved, numerical simulations are essential to developing quantitative models of the lives and deaths of star-forming GMCs. In this talk, I will describe results from recent radiation (magneto-) hydrodynamic simulations that have helped us to understand how star-forming GMCs self-regulate, while simultaneously regulating the thermal, ionization, and turbulent states of the distant diffuse ISM.

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January 2020

30/01/20 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — The Spiral Structure of the Milky Way
Mark J. Reid (Center for Astrophysics | Harvard & Smithsonian)
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Abstract

The Bar and Spiral Structure Legacy (BeSSeL) Survey uses Very Long Baseline Interferometry (VLBI) to provide  trigonometric parallax measurements for O-type stars across the Milky Way.  The Survey is named for Friedrich Bessel, who measured the first stellar parallax using the last telescope built by Muenchen's Joseph Fraunhofer.  I will show Bessel's original data and comment on its accuracy.

There are now about 200 parallaxes measured with VLBI, and these are accurately tracing spiral structure of the Milky Way, the distance to its center, its rotation curve, and the location of the Sun.  We have developed a Bayesian approach to leverage these results to estimate distances to large numbers of sources from surveys based only on Galactic coordinates and velocities.  Using this program we can make a realistic visualization of the Milky Way.

Additionally, our results make strong predictions for the distance of the Hulse-Taylor binary pulsar, assuming its orbital decay from gravitational radiation follows General Relativity, and for the proper motion of Sgr A*, if indeed it is a supermassive black hole.

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23/01/20 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Planet Formation Post-Kepler
Eugene Chiang (UC Berkeley)
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Abstract

The message of the Kepler space mission is this: super-Earths abound in the Universe. These are planets ~1--4 Earth radii and ~1--20 Earth masses, composed of solids and gas in proportions of 100:1 by mass. We describe how super-Earths/sub-Neptunes form within circumstellar disks of gas and dust. From basic astrophysical considerations of gas dynamical friction, gravitational scatterings and mergers, and atmospheric accretion by cooling, we infer a planet formation history that occurs largely in-situ, and late in the life of a protoplanetary disk.  We show how theory explains observed occurrence rate trends with orbital period, including the period ratio distribution that exhibits curious excesses near resonances, and can be expanded to accommodate rarer subpopulations such as sub-Saturns (a.k.a. "super-puffs"). Predictions will be highlighted.

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16/01/20 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — An overview of fast radio bursts in the era of plentiful discoveries and localizations
Laura Spitler (Max Planck Institute for Radio Astronomy)
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Abstract

Fast radio bursts are flashes of radio waves originating from so-far unidentified sources at cosmological distances. The bursts are luminous, have durations on the order of milliseconds, and occur often throughout the Universe. Some have been observed to repeat, while others have only been observed as "one-off" events. One of the biggest questions of the field is whether this is an astrophysical distinction or an observational bias. In any case over 50 cataclysmic and non-cataclysmic source models have been proposed, suggesting that multiple source populations of FRBs may be possible.

In roughly the first decade after their serendipitous discovery in 2007, progress was hampered by low numbers of detections and the inability to associate an FRB with its host galaxy. This changed dramatically in the last few years, as new telescopes began discovering large numbers of FRBs and achieving the spatial precision needed to associate FRBs to their hosts. In this colloquium I will provide an overview of the status of the field, including recent key discoveries by the Canadian Hydrogen Intensity Mapping Experiment (CHIME), the Australian SKA Pathfinder (ASKAP), and Deep Synoptic Array - 10. I will also discuss a few interesting sources in more detail, including FRB 121102, the first repeating FRB and the first FRB to be localized.

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09/01/20 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Particle Physics Beyond the Standard Model from X-ray Studies of AGN
Christopher Reynolds (University of Cambridge)
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Abstract

Discovering new physics beyond the Standard Model is the holy grail of modern particle physics. There has been a recent surge of interest in axions and axion-like particles, in part due to the possibility that they may constitute some fraction of the non-baryonic dark matter (coupled with the failure to detect weakly-interacting massive particles), and also due to the fact that they are generically-predicted by String Theories. In this talk, I shall discuss how astrophysical observations provide a multitude of powerful ways to constrain axion-sector physics. I shall particularly highlight how the transparency (or lack thereof) of the magnetized intracluster medium (ICM) to X-rays from embedded luminous AGN can be a powerful probe of axion-like particles. I will present new data from the Chandra X-ray Observatory for the Perseus cluster which allows us to set constraints on the properties of any low-mass axion-like particles that exceed those possible from the next-generation laboratory and ground-based searches. Our limits are already in moderate tension with predictions from String Theory. I shall end by highlighting the power of the Athena X-ray Observatory for future such studies.

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