November 2016

29/11/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — The Molecular Outflows in NGC 253 and Circinus as Revealed by ALMA
Laura Zschaechner (MPIA Heidelberg)

Abstract

Galactic outflows are poorly understood although they are essential to feedback processes that quench star formation and limit the total mass of large galaxies. Thus, insufficient understanding of feedback associated with them -- in particular of the molecular phase -- is one of the greatest shortcomings in our knowledge of galaxy evolution.  Multiphase outflows associated with galactic winds have been well-studied at a range of wavelengths, but detailed observations of the molecular phase are only now feasible with new instruments such as ALMA and NOEMA.  We present ALMA observations and kinematic models of the molecular outflows in Circinus galaxy and NGC 253.  Using these data, we constrain the molecular mass of the winds and mass outflow rates - both crucial to future star formation.  We explore the possibility of gas leaving the galaxies entirely, consider additional molecular gas tracers of physical conditions, and explore optical depth effects.  We compare the AGN-driven molecular wind in Circinus to the starburst-driven wind in NGC 253 and note key differences in the ways each type of wind impacts star formation.  We also consider how Circinus and NGC 253 adhere to current trends involving molecular outflows.

22/11/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Tracing Galaxies by their Shadows: Evolution of Metals and Dust in Galaxies from Quasar Absorption Systems
Varsha Kulkarni (University of South Carolina)

Abstract

Two of the basic questions in galaxy evolution are how galaxies get progressively enriched in heavy elements, and how the dust content of galaxies evolves. A primary challenge in observing distant galaxies is that the light emitted by them is often too faint to allow detailed studies. Absorption lines in quasar spectra can be used to probe interstellar gas in galaxies at various stages of evolution, and thus provide powerful probes of the history of star formation and chemical enrichment in galaxies. Using this technique, we found that the gas-rich damped Lyman-alpha (DLA) absorbers are on average metal-poor even at low redshifts. On the other hand, the less gas-rich sub-DLAs are more metal-rich on average, including some that reached several times the Sun's metallicity 7-10 billion years ago. We are now pushing the limits of this technique to reach galaxies in the first ~1 billion years after the Big Bang. We will discuss recent results for a sub-DLA at redshift z=5.0 which shows some unusual element abundances. We are also using the absorption-line technique to trace the evolution of cosmic dust with time. We have detected silicate dust in many quasar absorbers at redshifts z < 1.4. The dust in these galaxies appears to be different (e.g., more silicate-rich) compared to the dust in the Milky Way and the Magellanic Clouds. Furthermore, the silicate dust in some distant galaxies could be crystalline, unlike the interstellar dust in the Milky Way.

15/11/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — CARMENES: exoearths, M dwarfs and high-resolution spectroscopy from 0.5 to 1.7 µm
Jose Caballero (ZAH, Heidelberg)

Abstract

CARMENES stands for Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs) is a next-generation instrument built for the 3.5 m telescope at the Calar Alto Observatory by a consortium of German and Spanish institutions. It consists of two separated spectrographs covering the wavelength ranges from 0.52 to 0.96 µm and from 0.96 to 1.71 µm with spectral resolutions R = 80,000-100,000, each of which performs high-accuracy radial-velocity measurements (∼1 m s-1) with long-term stability. The fundamental science objective of CARMENES is to carry out a survey of ∼300 late-type main-sequence stars with the goal of detecting low-mass planets in their habitable zones. The science survey of Guaranteed Time Observations started on 01 Jan 2016 and will last for at least three years. I will briefly describe the homonymous instrument, consortium and science project, present preliminary results from our survey, and show our prospects for the future.

08/11/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Quasar Doppelgangers and the Implications for Cosmology
Michael Brotherton (University of Wyoming)

Abstract

Quasars, the accreting supermassive black holes at the centers of galaxies, are the most luminous objects in the universe and in principle ideal for use as so-called "standard candles."  Despite possessing a number of spectral features long known to correlate with luminosity, quasars have failed to live up to their potential this way.  We have employed statistical techniques to identify quasars with virtually identical spectra, which we call doppelgangers, in order to understand the limits of determining luminosity from spectral features alone.  While the majority of doppelgangers have very similar luminosity, there exists a surprisingly large scatter.  We offer some possible physical explanations for this large variance and their implications for cosmological application.

October 2016

25/10/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — White Dwarfs, Gaia, and The Age of the Galaxy
Ted von Hippel (MPIA Heidelberg)

Abstract

What is the star-formation history of the Milky Way?  How old are Galactic halo and thick disk stars?  Traditional age-dating of stars relies on clusters, which only offer a limited view of these stellar populations.  I will show that white dwarf stars offer a way forward.  Specifically, I will show how optical and near-IR photometry, Gaia astrometry, and a Bayesian modeling approach allows us to determine precision ages for individual white dwarfs and derive population ages.


18/10/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Galaxy evolution from the gas perspective
Toby Brown (Swinburne University, and The University of Western Australia)

Abstract

The importance of cold gas in the picture of galaxy evolution is well
known, as is its role as a probe of recent environmental effects on
galaxies. However, sensitivity limitations mean the extent to which
environment impacts the gas-star formation cycle of galaxies remains
unclear. With this talk I will show how we take full advantage of the
powerful HI spectral stacking technique to overcome this obstacle and
quantify the gas content for the entire gas-poor to -rich regime. This was
accomplished using an the largest sample of HI and multi-wavelength
information available (28,000 galaxies), selected according to stellar
mass (M*>10^9 Msol) and redshift (0.02 <= z <= 0.05). I will present HI
scaling relations with key structural, star formation and environmental
metrics, using stacking to provide strong observational evidence of
significant and systematic environment driven gas suppression across the
group regime, well before galaxies enter the cluster. Furthermore, I will
show that gas depletion is more closely associated to halo mass than local
density and cannot be reproduced by starvation of the gas supply alone,
invoking systematic ram-pressure stripping of the cold gas to explain
this. Finally, I will show preliminary results highlighting the role of HI
in regulating the correlation between stellar mass, star formation and
gas-phase metal abundance known as the “fundamental" mass-metallicity
relation.
04/10/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Advances in galactic astrophysics: space-time-scale-invariant dynamics and consequences for fundamental theory
Pavel Kroupa (University of Bonn)

Abstract

Starting with two of the greatest empirical discoveries in galactic dynamics which are in most cases not even mentioned in modern-day textbooks, namely the baryonic Tully-Fisher relation and the mass-discrepancy-acceleration correlation, augmented by observations such as Renzo's rule, I will discuss an underlying symmetry in the equations of motions. This space-time scale invariance leads to Milgromian dynamics, the origin of which needs to be understood and may perhaps be related to quantum mechanical processes in the vacuum.

September 2016

20/09/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Nearby galactic nuclei: excitation mechanisms in nearby LINER galaxies and the mass and distance of the Milky Way SMBH
Anna Boehle (University of California, Los Angeles)

Abstract

My talk will focus on the centers of nearby galaxies and the effects of central supermassive black holes (SMBHs) on the surrounding environment.  There has been increasing evidence that most, if not all, galaxies host SMBHs at their centers and correlations of the SMBH mass to host galaxy properties show that the growth of both are tied together.  SMBHs are additionally known to span more than 5 orders of magnitude in mass and can be extremely quiescent or the dominant energy source within a galaxy.  I will first discuss preliminary results from a survey of nearby LINER (low ionization nuclear emission line region) galaxies.  This class of active galaxies is common in the local universe, with ~1/3 of galaxies within 40 Mpc hosting LINERs, but their physical nature is not well understood.  The goal of the survey is to constrain the excitation mechanisms of near-infrared emission lines from singly ionized iron and molecular hydrogen using integral field spectroscopic observations at high spatial resolutions.  This survey is being conducted with the OSIRIS integral field spectrograph at the Keck Observatory, which we have recently upgraded with a new detector to roughly double the instrument’s sensitivity.  I will finally discuss the recent results of improved constraints on the mass and distance of our own Milky Way SMBH (Sgr A*).


13/09/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Stellar populations of bulges of isolated galaxies
Lorenzo Morelli (University of Padua)

Abstract

The stellar populations properties of galaxies and their gradients have received many attention in the last fifty years since they start to become crucial ingredients to test the predictions of the simulations describing the formation of galaxies. In the talk I will present our investigation on the stellar populations and their gradients of the bulge dominated regions focusing, in particular, on the isolated galaxies.

06/09/16 (Tuesday)
12:00, Library (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Highest precision limit on variation in the fine-structure constant from a single quasar absorption system
Srdan Kotus (Swinburne University, Melbourne, Australia)

Abstract

In the last 15 years, studies of velocity shifts between metal transitions observed in high-resolution quasar spectra with the largest optical telescopes identified possible evidence for variation in the fine-structure constant, α. Recent ‘supercalibration’ techniques have shown that these spectra likely have significant systematic distortions in their wavelength scales that undermine the α measurements.

We have selected the brightest southern quasar HE 0515-4414 at z_abs > 1 to obtain the highest S/N spectrum available, achieve the smallest statistical error on Δα/α to date and, most importantly, to allow systematic effects to be tracked and corrected with high fidelity. For this purpose we have combined HE 0515-4414 spectra observed with UVES/VLT over 10 years, producing an extremely high signal-to-noise ratio spectrum (peaking at ~250 pix^-1). This provides the most precise measurement of ∆α/α from a single absorption system to date, ∆α/α = −1.42 ± 0.55_stat ± 0.65_sys parts per million (ppm). This has a similar precision to previous measurements from large samples of ~150 absorption systems. This measurement is corrected for the largest systematic effect present in all (except one) previous measurements, the long-range wavelength distortions, which would add 10 ppm to the systematic error budget. We also discuss how our methods for correcting the spectra, in this case, can be applied to future spectra, in particular from the upcoming ESPRESSO spectrograph. Our spectrum also offers a preview of the data quality available from the next generation of telescopes, but also the problems that must be overcome to access the full photon-limited precision.

August 2016

25/08/16 (Thursday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Pete Worden (Chairman of the Breakthrough Prize Foundation)

Abstract

On July 20, 2015 at the Royal Society in London, Yuri Milner and Stephen Hawking announced a set of privately funded global initiatives to answer the fundamental science questions surrounding the origin, extent and nature of life in the universe. These include a Search for Extra Terrestrial Intelligence (SETI) called ‘Breakthrough Listen’ and a prize contest to devise potential messages in response to a SETI detection, entitled ‘Breakthrough Message’. The Initiatives are managed by the Breakthrough Prize Foundation and are funded at the $100M level.

On April 12, 2016 atop the One World Observatory in New York, Yuri Milner and Stephen Hawking announced ‘Breakthrough StarShot’. An initiative to develop and launch the Earth’s first interstellar probe to our nearest star within a generation. Facebook’s Mark Zuckerberg joined Milner and Hawking to oversee the initiative – initially funded at $100M.


July 2016

26/07/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — From the Tropics to the Poles: astronomy in unusual sites and EVA, a giga-pixel high-cadence survey telescope for the Arctic
Andrea Richichi (National Astronomical Research Institute of Thailand)

Abstract

Astronomical research has been historically neglected in Southeast Asia, but in recent years it has been experiencing a significant progress. In particular, the National Astronomical Research Institute of Thailand has assembled a core group of experienced researchers and several postdocs, and has developed modern facilities which include the largest telescope in the region, a 2.4-m equipped with imagers and spectrographs, and several smaller telescopes spread around the globe. Also a high-performance computing centre and a large radiotelescope are under development. I will present a brief review of the status, some scientific highlights and the collaboration opportunities concerning astronomical research in the region and in Thailand in particular. I will then focus on EVA, the Evryscope for the Arctic and Antarctic, a joint project between NARIT, the University of North Carolina at Chapel Hill and the University of Toronto. EVA follows in the footprints of the first Evryscope already operated at Cerro Tololo by UNC, which consists of 27 commercial lenses and large format detectors assembled on a single mount to cover about 8,000 sq degrees simultaneously each 2 minutes. The first EVA is planned to be deployed in the high Canadian Arctic in 2017/18, and targets a number of scientific cases ranging from transits of exoplanets to asteroseismology to stellar variability to transients and supernovae. A second EVA in the Antarctic is under consideration.

19/07/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — A Jovian Exoplanet in a Triple System and Mapping Clouds in Exoplanets and Brown Dwarfs
Daniel Apai (University of Arizona)

Abstract

In this talk I will present results from ground- and space-based projects in which we characterize exoplanetary systems and the atmospheres of giant exoplanets. Among other results I will show our VLT/SPHERE discovery of a jovian exoplanet in a triple stellar system, announced last week, and discuss the orbital and atmospheric properties of this surprising planet. I will also share results from our very large HST and Spitzer Space Telescope time-resolved studies of exoplanets and brown dwarfs, which allow us to study the properties and evolution of condensate clouds in these atmospheres with unprecedented details.
06/07/16 (Wednesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — A study of the circumgalactic medium at intermediate redshifts using DLA-galaxies
Hadi Rahmani (LAM Marseille)

Abstract

Circumgalactic medium (CGM), the interface between interstellar medium and intergalactic medium (IGM), provides a suitable site to study the IGM accretion and galactic outflows. QSO absorption line systems are amongst the best places to study the physical properties of the CGM. We have recently built a unique sample of 9 Damped Lyman-alpha (DLA) absorbers at z~0.6 from HST/ACS from which we identified 7 new DLA-galaxies at small impact parameters (<30 kpc) using VLT/X-Shooter. We estimate the metallicity of the CGM (0.05-0.6 Z_solar) and also the emission metallicity (0.2-0.9 Z_solar) and star formation rate of the host galaxies of DLAs. We further discover two quiescent galaxies that host huge neutral hydrogen reservoirs at impact parameters < 15 kpc. Here we demonstrate how a comparison between the properties of the host galaxies and the absorbing gas can be used to constrain the nature of the CGM.

June 2016

24/06/16 (Friday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Creating and Building the Hubble Space Telescope
Bob O'Dell (Vanderbilt University)

Abstract

Unlike Athena, who sprang full grown from the forehead  of Zeus, the Hubble Space Telescope had a long and difficult gestation. It was one of the original goals in building Earth orbiting satellites, but finally came under serious consideration only in 1971. The next two decades first saw battles to gain support from astronomers and financial support from the US and European governments. The next phase saw the challenges of designing and building something that had never been done before—a long duration observatory in space. I’ll then close out with an explanation of the problems with the primary mirror, how these were corrected, and a brief report on the observatory’s condition.


21/06/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — VMC star clusters science: an overview
Andres Piatti (Universidad Nacional de Cordoba)

Abstract

In this talk we will present results that come out from a partial exploitation of the VMC database, focussed on star clusters located in both Magellanic Clouds. Through a quick journey over our previous recent work, we will show the capability of the VMC database in reaching the main sequence turnoff of intermediate-age clusters, in uncovering the connection history of the SMC and the Bridge, in highlighting the spatial variation of the cluster formation history in the central regions of the LMC, in discovering new star cluster candidates in the densest part of the SMC, among others. Besides, we will describe some procedures developed for homogeneously analysing the VMC database.

14/06/16 (Tuesday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — The properties of dwarf spheroidal galaxies and their connections with the LCDM paradigm
Yves Revaz (EPFL, Switzerland)

Abstract

In this talk, I will address how the state of the art chemo-dynamical simulations, combined with the results of recent ESO/Large programs dedicated to chemical abundances of hundreds of individual stars, have improved our understanding of the formation and evolution of dwarf spheroidal galaxies (dSphs). Indeed, those new stellar abundances provide us with important constraints that must be fulfilled by numerical models. Thanks to a large sample of simulations  performed with our Tree/SPH chemo-dynamical code GEAR that treats the complex physics of baryons I will show how the large variety in the dSph properties can now be understood. In addition, I will discuss some tensions existing between dSph models and LCDM predictions.

07/06/16 (Tuesday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Beyond turbulence: a fundamentally different mode of star formation in Orion
Amelia Stutz (MPIA Heidelberg)

Abstract

By comparing 3 constituents of Orion A (gas, protostars, and pre-main-sequence stars), both morphologically and kinematically, we show the following. Essentially all of Orion A’s Integral Shaped Filament (ISF) protostars lie superposed on the ISF, while almost all pre-main-sequence (Class II) stars do not.  Combined with the fact that protostars move < 1 km/s relative to the filament, while stars move several times faster, this implies that a slingshot mechanism may eject protostars from the dense filamentary cradle, thereby cutting off their accretion of new gas. The ISF/ONC is the 3rd in a series of star bursts that are progressively moving south through Orion A, with separations of ~ 2 Myr in time and ~ 3 pc in space. This, combined with the ISF's observed undulations (spatial and velocity), suggest that repeated propagation of transverse waves thru the filament is progressively digesting the gas that formerly connected Orion A and B into stars in approximately discrete episodes.  The presence of transverse waves implies the action of a buoyant restoring force acting against gravity. Combined with previous observations of magnetic field geometry and strength in the ISF, this suggests that the ISF transverse waves are magnetically induced. The presence of straight filaments in low mass regions (e.g., Taurus and L1641) as well as in turbulence simulations indicates that Taurus-like filaments are a direct reflection of initial conditions. In contrast, the observed undulations of the ISF, the fact that the ISF is the only nearby cluster in formation, the fact that it has survived repeated burst of intense star formation, and the equality between the inferred gravitational potential energy and magnetic energy on ~ 1 pc scales near the filament ridge, together lead to the following conclusion: the key physical difference in the ISF is that it is massive enough to have survived the initial star formation episode, allowing it to undergo internal evolution leading to concentration of B-fields confined by a deep gravitational potential well.

May 2016

31/05/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Dark influences: the impact of dark satellites on dwarf galaxies in a LCDM universe
Tjitske Starkenburg (Kapteyn Institute, Groningen)

Abstract

The structure in our Universe is thought to have formed in a hierarchical fashion. As such, galaxies, and the dark matter halos in which they are embedded, grow through accretion, and through interactions and mergers with other galaxies. In the concordance (Lambda cold dark matter) cosmological model these interactions of galaxies and their halos are expected to be relevant on all scales, from large galaxy clusters to tiny dwarf galaxies. Moreover, within the LCDM framework small dark matter halos are ubiquitous, and many may not have been able to form stars. These small, star-less, halos are possibly indirectly detectable through their gravitational effects on luminous matter. Insights from these gravitational effects are perhaps promising for unveiling the presence of the hitherto missing satellites, and may provide novel clues to the nature of the dark matter.I will present a suite of simulations studying the effects of infalling dark satellites on dwarf galaxies. We find that these interactions can lead to the formation of irregular, starbursting, and spheroidal dwarf galaxies. Furthermore, we characterize the effects of small dark matter halos quantitatively through morphological and kinematical indicators to aid their observational identification. A significant fraction of the dwarf galaxies at the present day can be expected to have recently experienced such an interaction. Studying these interactions can shed light on dark influences on crucial episodes in the evolution of dwarf galaxies. Interactions with smaller dark matter halos may well contribute to the diversity of the dwarf galaxy population.

24/05/16 (Tuesday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Out of this world: exploring the Universe with the largest emission-line surveys
David Sobral (Lancaster University, UK)

Abstract

I will present new results regarding the first ~2 Gyrs of cosmic time using very wide-field Lyman-alpha (Lya) narrow-band surveys, including a large, matched Lya-Halpha survey to investigate how Lya and LyC photons escape (CALYMHA) from typical star-forming galaxies at high-redshift. We find that large Lya halos are ubiquitous in normal star-forming galaxies, and that the typical escape fraction of Lya and LyC photons is below a few percent. However, a fraction of the sources shows potentially very high escape fractions (~75%), hinting that LyC photons may escape at a significant rate but only from a small sub-set of the population with the right physical conditions.

We also find a much higher space density of very luminous Lyman-alpha emitters at z~2-7 than previously assumed, which we confirm spectroscopically with Keck and the VLT. At z~7 our sources (e.g. CR7) show signatures of PopIII-like stellar populations and/or direct collapse black holes. Our results are extremely important for our understanding of re-ionisation, showing that the  steep drop in the Lya luminosity function into the epoch of re-ionisation happens only for the faint Lya emitters, while the bright ones likely ionise their own bubbles very early on, and thus are visible at the earliest cosmic times.
17/05/16 (Tuesday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — The mass structure of galaxy clusters probed with strong gravitational lensing
Claudio Grillo (Dark Cosmology Centre, Copenhagen)

Abstract

Superb Hubble Space Telescope imaging and extensive Very Large Telescope spectroscopy, along with fundamental developments in the strong lensing modelling phase, have allowed us to measure with unprecedented precision the mass distribution of massive galaxy clusters acting as gravitational lenses. I will show how strong lensing models have been employed to reproduce the observed multiple-image positions of distant galaxies substantially better than thought possible even just a few years ago, to predict accurately position, magnification and time delay of a lensed supernova (SN ‘Refsdal’) before it became visible, to probe the structure and substructure properties of galaxy clusters, and to estimate the values of the cosmological parameters defining the global structure of the Universe. I will conclude by outlining the roadmap towards possible extensions beyond the current frontiers of strong lensing studies in galaxy clusters and their implications for cosmology.


10/05/16 (Tuesday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — To Be or not to Be: The Star, the Disk, and the Ugly
Dietrich Baade (ESO)

Abstract

Be stars account for 1-2% of all naked-eye stars, and in the local Universe ~5% of all SNe may have Be stars as their progenitors. They possess self-ejected Keplerian disks, from which the emission lines arise that add the attribute “e” to the spectral type.  Be stars rotate very rapidly but typically only reach 70% of critical rotation.  The missing energy is believed to be contributed by nonradial pulsation while viscosity redistributes angular moment in the ejecta such that the disks are rotationally supported.  Be disks are the closest and angularly largest disks in the family that ranges from accretion disks in young stars via mass-exchanging binaries to AGN.

I will describe the big leap forward in the understanding of the role of nonradial pulsation that has been enabled by space-precision photometry with micro- and nanosatellites.  The combination with long series of echelle spectra is vital for the distinction between stellar and circumstellar variations and has led to the development of a model describing the coupling of the star, the disk, and the transition region.

April 2016

26/04/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Cosmic Flows
Lister Staveley-Smith (ICRAR, University of Western Australia)

Abstract

I will report on progress on the new 2MTF survey to study cosmic flows in the nearby Universe and attempts to unveil extragalactic structure hidden behind the southern Milky Way using blind 21 cm surveys. I will also touch on future cosmology optical and radio surveys planned for TAIPAN and ASKAP.


19/04/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Towards an Understanding of the Black Hole Mass Scaling Relations
Vardha Bennert (California Polytechnic State University)

Abstract

The discovery of close correlations between supermassive BHs and their host-galaxy properties has sparked a flood of observational studies pertaining both to the local Universe and cosmic history over the last decade. Nevertheless, a clear understanding of their origin still eludes us. Uncertainty remains as to the fundamental driver of these relations, whether purely local and baryonic or global and dark matter dominated. While studying the evolution of these relations with cosmic time provides valuable clues, a definitive resolution of this conundrum relies on understanding slope and scatter of local relations for AGNs. We discuss results from a unique three-fold approach. (i) From a sample of ~100 AGNs in the local Universe, we build a robust baseline of the BH mass scaling relations (MBH-sigma, MBH-L, MBH-M), combining spatially-resolved Keck spectroscopy with SDSS imaging. (ii) We study the evolution of the MBH-sigma and MBH-L relations out to a look-back time of 4-6 Gyrs using Keck spectra and HST images. (iii) We extend this study out to the pivotal cosmic time between the peak of AGN activity and the establishment of the present-day Hubble sequence, a look-back time of 8-10 Gyrs. We measure spheroid stellar masses using deep multi-color HST images from GOODS and determine the MBH-M relation. The results (i) indicate that AGNs follow the same scaling relations as inactive galaxies. From (ii-iii) we conclude that BH growth precedes bulge assembly. Combining results from (i-iii) allows us to test the hypothesis that evolution is driven by disks being transformed into bulges.

12/04/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — ALMA: From the Solar System to the Galactic Centre
Liz Humphreys (ESO)

Abstract

ALMA Cycle 4 deadline is on April 21. For the first time, solar observations and mmVLBI including ALMA will be offered. In this talk I will give a whistle-stop tour round the galaxy to highlight exciting results for ALMA Galactic Science, and to give ideas for your ALMA proposals!

05/04/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — The Satellite Galaxy Planes Problem, suggested solutions and open questions
Marcel Pawlowski (Case Western Reserve University, Cleveland, Ohio)

Abstract

The satellite galaxies of the Milky Way and of the Andromeda galaxy preferentially co-orbit within narrow planes, and there is increasing evidence that satellite planes are also present around more distant hosts. Detailed comparisons show that similarly anisotropic phase-space distributions of sub-halos are extremely rare in cosmological simulations. This makes the satellite planes one of the most-serious small-scale problem for ΛCDM. In contrast to other small-scale problems, the satellite planes issue is not strongly affected by baryonic processes because the distribution of sub-halos on scales of hundreds of kpc is dominated by gravitational effects. While scenarios explaining the coherence of satellite positions and orbits exist, they all are currently unable to satisfactorily resolve the issue. Consequently, the current debate on this topic is highly controversial. Claims range from rejecting that there is significant evidence for the existence of satellite planes, over them being natural in cosmological simulations (despite not having been predicted), to them being catastrophic failures of ΛCDM cosmology itself. To understand the existence and origin of the satellite planes, we will have to move beyond a descriptive to a deductive use of the observed satellite correlations, and also consider additional, potentially related features and dwarf galaxy alignments in the Local Group.

March 2016

22/03/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Advances in Detecting Galaxies Hosting QSO Absorption Line Systems
Lorrie Straka (Leiden Observatory)

Abstract

Understanding the distribution of gas in galaxies and its interaction with the CGM is crucial in order to complete the picture of galaxy evolution. At all redshifts, absorption features seen in QSO spectra serve as a unique probe of the gaseous content of foreground galaxies and the CGM, extending out to ~200 kpc. Studies show that star formation history is intimately related to the co-evolution of galaxies and the CGM. In order to study the environments traced by absorption systems and the role of inflows and outflows, it is critical to measure the emission properties of host galaxies and their halos. However, the success rate for detecting host galaxies still incredibly low (in some cases, less than 30%). In recent years, great strides have been made towards overcoming the deficit of confirmed host galaxies compared to the number of observed absorption systems. New techniques and instrumentation have allowed us to overcome the challenge of detecting absorption host galaxies with the use of SDSS and the MUSE integral field spectrograph on VLT. SDSS provides the wide coverage at low redshift necessary to probe configurations of galaxies and QSOs in imaging, while MUSE's large field of view and sensitivity to emission lines has allowed a never-before seen match between the number density of absorbers along QSO sightlines and the number density of emission line galaxies within 200 kpc of the QSO. These galaxies represent a sample for which previously elusive connections can be made between mass, metallicity, SFR, and absorption properties.

18/03/16 (Friday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — ISM Dynamics and Star Formation
Ralf Klessen (Univ. Heidelberg)

Abstract

Stars and star clusters form by gravitational collapse in regions of high density in the complex multi-phase interstellar medium. The process of stellar birth is controlled by the intricate interplay between the self-gravity of the star-forming gas and various opposing agents, such as supersonic turbulence, magnetic fields, radiation pressure, and gas pressure. Turbulence plays a dual role. On global scales it provides support, while at the same time it can promote local collapse. This process is modified by the thermodynamic response of the gas, which is determined by the balance between various heating and cooling processes, which in turn depend on the chemical composition of the material. I discuss examples of recent progress and controversy. I address some puzzles and uncertainties in deriving galactic-scale star formation relations and argue that there may be a large reservoir of CO-dark H2 gas in disk galaxies such as our Milky Way. Also, I report of recent attempts to quantify the amount of diffuse CO emission in the Galaxy.

15/03/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — The redshift distribution of Dusty Star-Forming Galaxies from the SPT survey
Maria Strandet (MPIfR Bonn)

Abstract

In this talk I would like to present the extended redshift distribution of the South Pole Telescope (SPT) selected Dusty Star-Forming Galaxies (DSFGs).
We used ALMA to perform spectral scans between 84-114 GHz for 15 galaxies to obtain redshifts and to target an additional eight sources at 1mm to confirm redshifts for these sources. With APEX/FLASH and APEX/SEPIA we obtained [CII] and CO mid-J observations for five sources for which only a single line was detected in spectral-scan data from ALMA Cycle 0 or Cycle 1. We combine the new observations with previously published and new mm/submm line and photometric data of the SPT-selected DSFGs to study their redshift distribution. We find a median redshift of z=3.9 with the highest-redshift source at z=5.8. I will in the talk discuss how the selection of our sources affects the redshift distribution, focusing on source brightness, selection wavelength, and strong gravitational lensing.  The talk will also include a preliminary sneak peak of our newly received ALMA spectral scans.

08/03/16 (Tuesday)
11:45, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — The Star Formation Activity and Its Diversity of Low-Mass Galaxies at Cosmic Noon
Haruka Kusakabe (University of Tokyo)

Abstract

Low-mass galaxies at high redshift play a key role in galaxy formation and evolution as
building blocks of more massive galaxies seen at later epochs. I will talk about star formation
properties and their diversity of Ly-alpha Emitters (LAEs) at z ≃ 2.2, a commonly seen
low-mass galaxy population. First, by stacking deep Spitzer/MIPS and Herschel/PACS
images for 213 LAEs in the GOODS-South, we find for the first time that LAEs typically
have very low IR luminosities less than L^{3sigma}_{TIR} = 1.1 x 10^{10} L⊙
(3 sigma upper limit) and that their attenuation curve is consistent not with the Calzetti curve
but with the SMC curve (Kusakabe et al. 2015, ApJ, 800, L29). Second, we divide 604 LAEs
in the SXDS field into sub-samples based on the distribution of four UV physical parameters:
M_{UV}, beta, L_{Ly-alpha}, and EW_{Ly-alpha,r}.
Then, we calculate the halo mass and stellar population parameters for each sub-sample
from clustering analysis and SED fitting with SMC curve, respectively.
While two thirds of the entire sample are on the SFMS with stellar masses of ~10^9 M⊙,
the remaining one third, which are the lowest-mass objects in our sample, are forming
stars burstly with stellar masses of ~10^7 M⊙ with SFRs exceeding the baryon accretion
rates of their hosting halos. These low-stellar mass LAEs may be in initial forming phases
at cosmic noon (Kusakabe et al. in prep).

01/03/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — The growing field of post-main-sequence exoplanetary science
Dimitri Veras (University of Warwick, UK)

Abstract

The quest for identifying the bulk chemical composition of extrasolar planets and robust observational evidence that between 25% and 50% of all Milky Way white dwarfs host currently dynamically-active planetary systems motivate investigations that link their formation and fate.  Here I provide a review of our current knowledge of these systems, including the groundbreaking recent discovery of multiple co-orbital disintegrating planetesimals around white dwarf WD 1145+017.  I show how this field incorporates several facets of astrophysics and planetary science, including orbital dynamics, stellar evolution, astrochemistry, atmospheric science and surface processes.  I outline the fundamental outstanding questions which remain about the origin and evolution of these fascinating systems.

February 2016

23/02/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Deep Keck Spectroscopy of High-Redshift Quiescent Galaxies
Sirio Belli (MPE)

Abstract

The recent development of sensitive near-infrared detectors has opened up a new window for the study of high-redshift galaxies. Using the new near-infrared capabilities of the MOSFIRE and LRIS instruments at the Keck observatory, we have undertaken a spectroscopic survey of about 100 quiescent galaxies in the redshift range 1 < z < 2.5. Our deep spectra reveal the rest-frame optical absorption lines, which are the most effective probe of the physical nature of quiescent galaxies, and allow us to measure velocity dispersions and stellar ages. In particular, we are able to overcome the issue of connecting galaxy populations at different redshifts, which is the most challenging aspect of observational studies. I will discuss our main results, including the comparison of dynamical and stellar masses, and a solution for the puzzling size growth of quiescent galaxies.

16/02/16 (Tuesday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — First scientific results from BRITE satellite mission
Andrzej Pigulski (University of Wroclaw, Poland)

Abstract

BRIght Target Explorer (BRITE) is the first scientific mission using nano-satellites for making observations from space. It is aimed at precise photometry of the brightest stars in the sky. Equipped with either blue or red filter, BRITE satellites provide up to six-month long observations of selected stars. This allows for a detection of multimode pulsations with sub-mmag amplitudes as well as many other types of variability. Most of about 300 up-to-date observed targets are massive hot main-sequence stars. I will summarize the objectives of the mission and show a few examples of the first scientific results based on BRITE data.

09/02/16 (Tuesday)
12:30, Fornax (ESO HQ, Garching) | ESO Garching
Lunch Talk
Talk — Cleaning up the Mysteries of Star Formation with Ammonia
Erik Rosolowsky (University of Alberta, Canada)

Abstract

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

02/02/16 (Tuesday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — The SAMI Galaxy Survey: Kinematics, outflows, and AGN
Rebecca McElroy (University of Sydney)

Abstract

The SAMI Galaxy Survey is a pioneering multiplexed optical integral field spectroscopic survey that upon completion will comprise 3400 galaxies. Such a large sample of spatially resolved galaxies will allow us to tackle the fundamental questions of galaxy evolution that remain elusive in smaller samples. This talk will present some of the key science results produced by the SAMI team thus far and how this relates to my own PhD work on a distinct sample of luminous local AGN.

January 2016

26/01/16 (Tuesday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Modeling the cold interstellar medium of galaxies
Livia Vallini (University of Bologna)

Abstract

The advent of ALMA makes it possible either detections of far-infrared (FIR)
metal and molecular cooling lines arising from single galaxies that formed at the
end of the Reionization Epoch (EoR), and blind surveys that aim at following
the global evolution of cold gas across cosmic time. In the first part of this talk
I will focus on the cold neutral gas. I will present a theoretical model that,
coupled with high resolution radiative transfer cosmological simulations, allows
to predict the luminosity of [CII] 158 µm line arising from the neutral diffuse gas
and from dense Photodissociation Regions. I will show that the model has been
successfully used to interpret ALMA [CII] detections in galaxies at the end of
EoR, and how we can use the [CII] line to put constraints the relative abundance
of different gas phases composing the ISM of the first galaxies. In the second
part, I will focus on the cosmic evolution of the molecular gas mass fraction.
I will discuss how a proper decomposition of the FIR luminosity function can
be exploited to derive the evolution of the CO luminosity function for different
galaxy classes and in particular of the AGN.

12/01/16 (Tuesday)
12:30, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Observing the reservoir for star formation
Natasha Maddox (ASTRON, Netherlands)

Abstract

While the star formation density over cosmic time is well studied, very little is known about neutral hydrogen, the fuel for star formation, over the same epoch. I'll give an overview of current observations, look ahead to upcoming surveys in the era of the SKA, and motivate why these efforts are essential for a complete picture of galaxy formation and evolution.