Seminars and Colloquia at ESO Garching and on the campus

The chemical enrichment of the Universe is considerably affected by the contributions of Giant stars. Giant and supergiant stars are surrounded by a hot layer called the chromosphere, which could likely powers Magneto-Hydrodynamic Alfven waves that drive their mass loss. Toward the end of their life, on the Asymptotic Giant Branch (AGB), stars produce heavy chemical elements, molecules, and dust, which, through the mass loss provided via their stellar winds, are placed into the interstellar medium.

This talk will explore ongoing work modeling high-resolution spectroscopic observations with Hubble Space Telescope instruments (Rau et al. 2018, subm.), to reveal the role of the chromosphere in driving K-M giant and supergiant winds. Our results include estimates of wind and chromospheric parameters, mass-loss rates, and fundamental stellar parameters.

In addition, ground-based interferometric measurements with high-angular resolution instruments from VLTI, such as MIDI (Rau et al. 2015, Rau et al. 2017), GRAVITY (Wittkowski et al. 2018), help to test geometrical and dynamical models describing the behavior of the outer AGB atmospheres at various spatial scales. In this way we are able to unravel the role of molecules and dust in their extended atmospheres.Future plans include the use of high-angular resolution instruments such as VEGA at CHARA, and MATISSE at VLTI, to better understand the behavior of cool stars outer atmospheres at various spatial scales.

The current success of the VLT and VLTI in high angular resolution, the generalisation of adaptive optics result from a dream born in the 1970s, emerging in the 1980s during the conceptual design of the VLT, implemented in the 1990s. During three decades, ESO and its European partners took the lead with tenacity. The talk will remind some of the decisive, and sometimes critical, moments of this long story and depicts some of its main actors. 

The diagnostic power of IR spectroscopy will be of crucial importance to study the galaxy evolution during the dust-obscured phase at the peak of the star formation and black-hole accretion activity (1 < z < 4). The unique suite of spectral lines and dust features present in the mid- to far-IR range allow us to determine the physical conditions in galaxies (e.g. density, ionisation, metallicity) using robust tracers with a feeble response to both extinction and temperature. The SPace IR telescope for Cosmology and Astrophysics (SPICA), a 2.5m cryogenic (< 8K) IR telescope (12-230 micron) currently in competition for the ESA medium-class mission call M5, has been particularly designed to study the physical processes that govern the formation and evolution of galaxies and black holes through cosmic time. Taking advantage of diagnostic tools in the mid- to far-IR range, SPICA will be able to: i) obtain the first spectroscopic determination of both the star-formation rate and black hole accretion rate histories of galaxies in the last 12 Gyr for large statistically significant samples; ii) unveil the role of feedback in galaxy evolution during the last 10 Gyr and explore the detectability of metal-rich inflows in the local Universe, characterising the duty cycle in galaxies; iii) investigate the chemical evolution of galaxies and the dust composition up to z ~ 4; iv) trace the evolution of dust obscured galaxies back to the epoch of reionisation. Finally, I will also discuss the possible synergies between SPICA (planned for ~2030) and future first-class facilities (JWST, ELTs, Athena, SKA).

With the increasing precision of a wide range of cosmological measurements, tensions are starting to appear in the previously concordant model of Cosmology.  Examples are the discordance between direct measurements of the Hubble expansion rate, and the clustering of dark matter, in comparison to their predicted values from the Planck CMB measurements.

In this talk I’ll review cosmological parameter constraints from the Kilo Degree Survey (KiDS), a now almost complete ESO survey that studies the growth of structures and the expansion history of the Universe using weak gravitational lensing.   As our analysis also finds a low-redshift universe that is in mild tension with the predictions of the Planck CMB experiment, I’ll discuss whether these recent results are our first hint that the Universe is rather more exotic than the standard LambdaCDM model would suggest, or whether this is a sign that new data challenges lie ahead.

I will review the current theoretical understanding of first stars and black holes and their potential contributions to the Cosmic Infrared Background (CIB). Intriguing indications of the possible emissions from these objects have been obtained from source-subtracted CIB fluctuation measurements using Spitzer/IRAC deep images. The uncovered source-subtracted CIB fluctuations substantially exceed those from remaining known populations. The spatial spectrum of these fluctuations is consistent with populations clustering according to high-z LCDM model. The SED of the CIB fluctuations is blue and consistent with emissions produced by hot objects at high z. Cross-correlation analysis with Chandra X-ray data suggests that the unresolved CIB and CXB are coherent at a remarkably high level implying a fractional abundance of black holes, among the emitters of the CIB, which significantly exceeds that in known populations. I will then discuss an ongoing CIB project, LIBRAE (Looking at Infrared Background Radiation Anisotropies with Euclid), approved by NASA and ESA for the Euclid satellite mission.  LIBRAE will identify the net emissions from the first stars era, lead to a better understanding of the condition of intergalactic medium at that epoch, and, in conjunction with eROSITA, accurately isolate the contributions from the first black holes.

The PAH features detected in the infrared range between ~3 and 20um have been extensively used as reliable indicators for distinguishing the dominant energy source of dusty galaxies, such as starburst or active galactic nucleus (AGN). The 3.3um PAH feature is the only PAH feature that will be observable with the James Webb Space Telescope (JWST) at z > 3.5, because the rest of the features at longer wavelengths fall outside the JWST wavelength coverage. However, detailed studies that compare the most frequently used 3.3um and 6.2um PAH features are still limited, because the former was only observable with the AKARI infrared astronomical satellite and the latter was only observable with the Spitzer Space Telescope. In this talk, I will show a direct comparison between the 3.3um and 6.2 PAH feature detected in ~150 local luminous infrared galaxies, which are the best analogs for star-forming galaxies in the early Universe. Then, I will discuss how to adapt these results based on the rest-frame 2-5um range to observe high-z galaxies with JWST.

Type Ia supernova are powerful cosmological distance indicators that enable us to measure the expansion history of the Universe. Using SNe Ia distances, scientists discovered the accelerating expansion of the Universe, leading to a Nobel prize and a broad focus on understanding the underlying cause of this acceleration.  SNe Ia distances are also key to measuring the Hubble Constant, the current expansion rate of the Universe and a key cosmological parameter.  Interestingly, the SNe Ia measurements of H0 are ~4 sigma away from the those derived from CMB temperature anisotropy measurements from Planck.  This highly discussed tension could be a sign of new physics, such as a new family of neutrinos.  However, I will discuss how recent studies of SNe Ia in the nearby Universe indicate two separate populations of SNe Ia with different peak luminosities. These differences in the underlying SNe Ia population could introduce a bias in the derived H0 and be the true cause of the tension with CMB measurements.

Over the past 45 years, investigations of ultraviolet absorption features in stellar spectra have revealed that most of the heavy elements in the interstellar medium are depleted from the gas phase to values well below solar or B star reference abundances. The strengths of such depletions reveal the composition of dust grains in space, and they can be characterized by a limited set of empirical parameters that can be linked to the average gas densities and the condensation temperatures of the elements. Two outstanding mysteries remain: one is the fact that the depletion of oxygen exceeds that needed for forming silicates or metallic oxides, and the other is that the chemically inert element krypton shows some depletion. When we observe absorption features in the spectra of quasars to derive the element abundances in foreground intervening galaxies, we can correct for effects of depletions by using the patterns found in our Galaxy or the Small Magellanic Cloud as examples.

In this talk I will present pioneering work on the panchromatic emission of some of the most luminous galaxies in the early Universe: star forming galaxies and Active Galactic Nuclei. Using state-of-the-art statistical methods and new-generation radio-to-UV instruments, the presented results expand the parameter space covered by current multi-wavelength studies, pushing three different frontiers: the statistical frontier, the wavelength frontier and the resolution frontier. I will introduce a sophisticated statistical tool to robustly model the multi-wavelength emission of galaxies and AGN to push the statistical frontier. The wavelength frontier is pushed forward by exploring galaxy evolution from a new spectral window at low radio frequencies, opened by the LOFAR instrument. Finally, the resolution frontier will be pushed by exploring the resolved distribution of emission components across the spectrum using a combination of high-resolution ALMA and HST imaging.

The physical mechanisms leading to the formation of Infrared Dark Clouds (IRDCs) are not completely understood and it is thus important to study their molecular gas kinematics and chemical content to search for any signature of the IRDCs formation process. Using the 30-m-diameter antenna at the IRAM30m telescope, we have obtained emission maps of dense gas tracers and typical shock tracers (SiO and CH3OH) towards three IRDCs and we have studied the molecular gas kinematics in these clouds. The IRDCs show complex gas kinematics substructures with correlated widespread (parsec-scale) emission of SiO and CH3OH. However, for one of the clouds the sample the detected widespread SiO and CH3OH emission shows very narrow line profiles and may have originated in a large-scale shock interaction.

The majority of galaxies host a very dense and massive star cluster in their centres. Often these nuclear star clusters (NSC) are the only surviving remnants of tidally disrupted galaxies and are usually classified as very massive globular clusters or ultra-compact dwarfs. At difference with typical globular clusters, however, NSCs often  have extended star formation histories (SFH). In this talk I will present the SFH of M54 (the NSC of the Sgr dwarf galaxy, currently under disruption by the tidal field of the Milky Way) as derived from a large MUSE data set of several thousand spectra of individual stars. I will also present the SFH analysis of the NSCs of several nearby galaxies, based on integrated light spectroscopy from X-Shooter, and argue that we are able to distinguish between the two main mechanisms of NSC formation: in situ star formation at the centre of the galaxy vs. stellar accretion.

Open access to scientific results is rapidly gaining importance over the entire spectrum of scientific research. In particular for astrophysics, an important part of the research process includes the development of source codes.

Journal articles detail the general logic behind new results and ideas, but often the source codes that enable these results remain hidden from public view. In this presentation, I will discuss our recent study on the availability of source codes used for published astro research and how this affects the transparency and reproducibility of this research. The Astrophysics Source Code Library (ASCL, ascl.net) was started in 1999 to encourage software availability and thus improve research transparency. I will cover what the ASCL is, how to submit software to the resource, and the benefits of doing so.

I will share how ASCL enables links between literature and software entries, in ADS and how an ASCL ID can be used for citing your code. I will also cover good and bad ways to cite software, avenues for publishing software, and how journals are changing to include and recognize the contribution software makes to our discipline.

Using multi-wavelength data, from UV-optical-near-mid IR, for $\sim$6000 galaxies in the local Universe, we study the dependence of star formation on the morphological T-types for massive galaxies ($\log M_*/M_\odot \geq 10$). We find that, early-type spirals (Sa-Sbc) and S0s predominate in the green valley, which is a transition zone between the star forming and quenched regions. Within the early-type spirals, as we move from Sa to Sbc spirals the fraction of green valley and quenched galaxies decreases, indicating the important role of the bulge in the quenching of galaxies. The fraction of early-type spirals decreases as we enter the green valley from the blue cloud, which coincides with the increase in the fraction of S0s. This points towards the morphological transformation of early-type spiral galaxies into S0s which can happen due to environmental effects such as ram-pressure stripping, galaxy harassment, or tidal interactions. We also find a second population of S0s which are actively star-forming and are present in all environments. Since morphological T-type, specific star formation rate (sSFR), and environmental density are all correlated with each other, we compute the partial correlation coefficient for each pair of parameters while keeping the third parameter as a control variable. We find that morphology most strongly correlates with sSFR, independent of the environment, while the other two correlations (morphology-density and sSFR-environment) are weaker. Thus, we conclude that, for massive galaxies in the local Universe, the physical processes that shape their morphology are also the ones that determine their star-forming state.

Low-mass stars form via gravitational collapse of molecular cloud cores.  Although their formation has received considerable attention in the last few decades, the rate at which a star gains most of its mass and the physics that drives the main phase of stellar growth is still not understood. Most protostars have luminosities significantly fainter than the luminosity expected from steady accretion over the protostellar lifetime.   The solution to this problem may lie in episodic mass accretion -- prolonged periods of very low accretion punctuated by short bursts of rapid accretion.  In this informal discussion, I will describe these challenges and initial constraints on protostellar variability from the East Asia Observatory JCMT/SCUBA2 sub-mm monitoring program of eight nearby star forming regions, the first large sub-mm variability program.

We present morphological properties of dusty star-forming galaxies at z = 1-3 determined with the high-resolution (FWHM~0.′′19) ALMA 1-mm band maps of our ASAGAO survey covering a 26-arcmin2 area in GOODS-S and the ALMA archive. The present sample consists of 45 ALMA sources with a wide rest-frame far-infrared (FIR) luminosity L_FIR range of 10^11-13 L⊙. To obtain an average rest-frame FIR profile, we perform individual measurements and careful stacking of the ALMA sources using the uv-visibility method that includes positional-uncertainty and smoothing-effect evaluations through Monte-Carlo simulations. We find that the dusty star-forming galaxies have the average FIR-wavelength Sersic index and effective radius of n_FIR = 1.2+/-0.2 and Re_FIR =1.0-1.3 kpc, respectively, additionally with a point source at the center, indicative of the existence of AGN. The average FIR profile agrees with a morphology of an exponential-disk clearly distinguished from a spheroidal profile (Sersic index of 4), and supports a positive correlation of the FIR size-luminosity relation. We also examine the rest-frame optical Sersic index n_opt and effective radius Re_opt with the deep HST images. Interestingly, we obtain n_opt = 0.9+/-0.3 (~ n_FIR) and Re_opt = 3.2+/-0.6 kpc (> Re_FIR), suggesting that the dusty disk-like structure is embedded within a larger stellar disk. The rest-frame UV and FIR data of HST and ALMA provide us a radial surface density pro le of the total star-formation rate (SFR), where the FIR SFR dominates over the UV SFR at the center. Under the simple assumption of a constant SFR, a compact stellar distribution found in z~1-2 compact quiescent galaxies (cQGs) is well reproduced, while a spheroidal stellar morphology of cQGs (n_opt = 4) cannot, suggestive of other important mechanism(s) such as dynamical dissipation.

Ages of pre-main sequence stars are notoriously uncertain, with implications for measurements of envelope and protoplanetary disk survival times and for quantifying local star formation histories. In any given cluster, a spread of apparent ages may be caused by individual differences in stellar evolution, by observational errors, or by a real age spread; discrepancies in ages versus stellar mass undermine the reliability of absolute age estimates for clusters.  I will discuss how uncertainties in early accretion histories affect the location of the stellar birth, how uncertainties in the internal structure affect the subsequent contraction, and how these uncertainties are being addressed with improved models and observational approaches.

With the rise of large-scale spectroscopy surveys, the amount of self-consistent data has reach unprecedented magnitudes. This data can be used to derive a multitude of parameters for the targeted galaxies, which allowed us to apply various redshift-independent distance indicators to them. We also took the opportunity to further improve established tools, such as the fundamental plane, using additional insights gained by the multitude of data. In combination with redshift-data, we are able to derive the peculiar motion field for a large area of the observable universe. Additionally, we provide a comparison to the peculiar motion data derived using other distance indicators.

About 3,000 planetary nebulae (PNe) and 250 symbiotic stars (SySts) are known in the Galaxy. Only 14 PNe and around 5% of the SySts are located at highGalactic latitudes. This contribution presents the preliminary results of a project aimed at to identify PNe and SySts in the direction of Galactic halo, by using the Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS), the Javalambre-Photometric Local Universe Survey (J-PLUS) and the SouthernPhotometric Local Universe Survey (S-PLUS). The main advantage of these surveys is their great combinations of narrow- and broad-band filters, in total 56,12, and 12 filters, respectively, from 3,000 to 10,000 Å. The optical spectra of several types of sources as well as a grid of PN photoionization models, convolved to the photometric systems of the three surveys, are used to generate combinations of colour-colour diagrams that discriminate halo PNe and SySts from other emission line objects (star-forming galaxies; QSOs; cataclysmic variables; extragalactic H II regions; young stellar objects; Be stars; among others). The J-PLUS science verification observations of two known halo PNe (H 1-4 and PNG 135.9+55.9) are actually located in the locus of PNe/SySts we defined in the colour-colour diagrams. New halo PN and SySt candidates, selected in the J-PLUS and S-PLUS Early Data Releases, will be discussed in this contribution.

The extremely metal-poor stars (EMP) hold in their atmospheres the fossil record of the chemical composition of the early phases of the Galactic evolution. The chemical analysis of such objects provides important constraints on the early chemical enrichment of the Galaxy.  EMP stars are very rare objects; to dig them out the analysis of large amounts of data is necessary. I will present how these most metal poor stars can be found and present the methods which allow to determine their chemical composition.

Damped Lyman-alpha absorbing systems (DLAs) in the sight line ofbackground quasars and gamma-ray bursts (GRB) offer a unique way tostudy the conditions of star forming regions in high redshift galaxies.Now, for the first time, we are able to use a large and complete sample of 22 GRBsat redshift z > 2 observed with X-shooter to measure the abundances of metals,molecules, and dust, in order to study effects of metallicity, dust depletion andnucleosythesis in the high redshift interstellar medium. To do so, we developednew, state-of-the-art methods, based on the Python Bayesian inferencepackage PyMC, to fit absorption lines in order measure the columndensities of 10 different elements as well as neutral and molecular hydrogen.The measured relative abundances are further used to fit depletion sequencesand determine the dust-to-metals ratio and the host intrinsic visual extinction.In this talk, I want demonstrate our new methods, present the results, and discuss theirimplication for the nature of high-redshift GRB DLAs.

So far most of what we have learned about the stellar content of Early-Type Galaxies come from the visible, particularly for detailed spectroscopic studies. New observational facilities and new modeling means allow us to start exploiting the near-IR spectral range. Good fitting solutions should work out for both the Near-IR and the optical ranges. I will show you new results, but most importantly, will discuss with you the potential of this spectral range for constraining the SFHs, IMF and abundance ratios of these galaxies.

A stellar cusp in a dense stellar system around a massive black hole is a firm prediction of stellar dynamics. Nevertheless, observational evidence from the nuclear cluster of the Milky Way appeared to contradict the theoretical expectations. In this talk we will review the topic and present the latest observational work that provides evidence, from multiple tracers, that the cusp exists.  Its existence implies that we can expect to observe a significant amount of EMRIs with future space based gravitational wave observatories. We confirm previous findings that the cusp is not observed in the bright giants. The “missing cusp” problem is thus a “hidden cusp” problem and some mechanism must have altered the appearance of the giants near  Sagittarius A*.

The Galactic Center offers the unique possibility to quantitatively test general relativity in the so-far unexplored regime close to a massive black hole. Here we present the latest results from the peri-passage of the star S2 in May 2018. As the star approached the black hole as close as 17 light hours and a speed of almost 8000 km/s, we have followed its orbit with SINFONI spectroscopy and GRAVITY interferometry at the ESO Very Large Telescopes. The GRAVITY instrument, which we have developed specifically for the observations of the Galactic Center black hole and its orbiting stars, is now routinely achieving ~3 milli-arcsec imaging interferometry and with a sensitivity several hundred times better than previous instruments. Its astrometric precision of few ten micro-arcseconds corresponds to only few Schwarzschild radii of Galactic Center massive black hole. The door is now wide open for the quantitative analysis and interpretation of the fundamentals of gravity, all the way from the underlying equivalence principles, to considerations on new physics and their characteristic scales and strengths. The Galactic Center is and will remain the Rosetta-stone for deciphering strong gravity around massive black holes.

Type Ia supernovae originate from the explosion of carbon-oxygen white dwarfs in binary systems,but the exact nature of their progenitors remains elusive. Recent studies have found that theX-ray bulk properties of Type Ia supernova remnants, such as the radius and the Fe Kalpha centroid energy and luminosity, can discriminate between progenitor energetics and circumstellar environments.Using Chandrasekhar, and for the first time, sub-Chandrasekhar models for the chemical composition of Type Ia supernova ejecta, we model the dynamical and thermal evolution of supernova remnants up to 5000 years for several uniform ambient media in one dimension. We generate synthetic X-ray spectra from these models with updated atomic data and compare these bulk properties for different expansion ages with X-ray observations from the Chandra and Suzaku telescopes. We find an overall agreement between our models and the observational data. We also find that the ambient medium density and the expansion age are the main contributors to the X-ray diversity of these bulk properties, not the progenitor scenario. Detailed X-ray fittings that determine chemical abundances or flux ratios are needed to discriminate between Chandrasekhar and sub-Chandrasekhar progenitor scenarios.

There are massive galaxies that remain untouched since the high-z Universe. These objects, the so-called relic galaxies, are massive (M_stellar > 8x10^10 M_Sun), very small (effective radius < 2 kpc) and display old (>10 Gyr) stellar populations (thus being red nuggets but at low-z!). For the very few of them already found and analysed, they seem to host übermassive black holes, to show a bottom-heavy IMF and to retain early disk morphologies and kinematics. How did they survive until the present day? Simulations predict that they live in galaxy overdensities whose large velocity dispersions prevent galaxies from merging. However, we have not yet determined observationally neither the environments these galaxies inhabit nor their number densities. The large area and spectroscopic completeness of the GAMA survey allows us to conduct a complete census of this elusive galaxy population, and also to analyse their structural parameters. After inspecting ~150 deg^2 of ancillary KiDS and VIKING photometric data, we have identified 21 of these objects at 0.02 < z < 0.3, that are true windows to the primeval Universe. I will present the first paper introducing this exceptional sample, describing its properties and highlighting the fact that while some of galaxies seem to be satellites of bigger objects, others live in the field, at odds with the theoretical expectations.

Modified Newtonian Dynamics (MOND) is an alternative to non-baryonic dark matter, proposed by Israeli physicist Moti Milgrom in 1983. It aims to explain the mass discrepancies observed in the Universe by changing the laws of dynamics instead of postulating new particles. MOND is a general paradigm that includes different physical theories, such as modified gravity and modified inertia. I will start with a brief review of the general paradigm and its predictions. If time allows, I will also illustrate some non-relativistic MOND theories and possible relativistic extensions. In general, MOND is successful on galaxy scales, it has problems on galaxy cluster scales, and it's almost entirely mute on cosmological scales (CMB, large scale structure). In this regard, MOND is diametrically opposed to LCDM in terms of explaining/predicting power, so it is generally difficult to properly compare the two paradigms.

We present a new universal star formation law based on the probability density function (PDF) and sonic Mach number of the turbulence in star-forming clouds. In our relation the star formation rate (SFR) correlates with the molecular gas mass per multi-freefall time. We show that the actual SFR is only about 0.45% of the maximum possible SFR, confirming the observed low efficiency of star formation. We show that placing observations in the framework of our developed relation yields a significantly improved correlation with 3-4 times reduced scatter compared to previous star formation relations, such as the Kennicutt-Schmidt or the Krumholz-Dekel-McKee relation. We use this new relation to develop a new method for estimating the column density of cold molecular gas (Σgas) using integral field spectroscopy. We utilise the spatially resolved Hα maps of flux and velocity dispersion from the Sydney-AAO Multi-object Integral-field spectrograph (SAMI) Galaxy Survey to make our estimates. Finally, we present and utilise data from the Combined Array from Research in Millimeter Astronomy (CARMA) and Herschel Space Telescope to measure the star formation efficiency across the face-on Hickson Compact Group galaxy NCG7214. We find that this galaxy is extremely inefficient and cannot be described by star formation relations developed in previous literature. We therefore extend our multi-freefall star formation relation to take into account the virial parameter of the turbulent clouds, which yields significantly improved predictions of the SFR compared to any previous star formation law.

The study of the CI in the nearby Universe and at high redshifts has shown that CI is a very powerful tracer of the molecular gas in the galaxy interstellar medium and starts giving an advantage at z>0.5 because it remains well excited for cooler lower density molecular gas and it is optically thin (no need of the XCO factor).
When coupled with high-J CO emission lines the ratio, high-J CO/CI, is a good proxy of (warm, dense, star-forming (SF) gas)/(total H2 gas) mass fraction and provides a unique insight on the main source heating the gas and therefore indicating whether a system is merger driven or disc-like.
I show observations of three lensed galaxies at z~3  obtained with the APEX/SEPIA5 receiver and a few ALMA observations towards high-z submm galaxies and derive conclusions on the dominant power source of the molecular ISM of these objects.

It is now well established that the star formation rates (SFRs) of galaxies are reduced by their passage through a dense environment.  However, the processes responsible for this suppression are uncertain, as are the timescales over which they act.  Some observational constraints have provided evidence for fast (<~ 500 Myr) suppression while others support a long timescale (2-5 Gyr).  A successful model for resolving this discrepancy is a “delay+rapid” quenching model, in which galaxies enter a cluster and are unaffected for a period of time, the “delay” period, followed by a rapid quenching event.  While this model is successful at explaining many aspects of quenching in clusters, it is unknown what happens to galaxies in the “delay” period.  I will discuss a set of completed and in prep. papers from the Local Cluster Survey that address this issue. We use spatially resolved observations of star formation tracers in star-forming galaxies in 9 nearby clusters to understand how the star-forming disks of cluster galaxies are affected by their environment.  We find that spatially resolving the star formation is a crucial ingredient to understanding environmental transformation and I will present our results on the relative size and shrinking timescales of star-forming disks inside and outside the clusters.  I will also discuss the implication that this has for understanding how the spatially integrated SFRs of galaxies are modified as they enter dense environments.

Africa is becoming a focus of the world's radio astronomy community. Evidently, South Africa is unveiling the 64-antenna MeerKAT Radio Telescope, the African's precursor to the world's next generation radio telescope, the SKA, on July 13, 2018 at the SKA Losberg site in the Karoo. It is envisaged that the SKA Phase 2 will have arrays extended to the eight SKA African Partner Countries that include Ghana. Prior to this, African VLBI Network (AVN) is being built with the converted and refurbished 32m satellite communication earth station antenna now at the Ghana Radio Astronomy Observatory (GRAO), as the first non-South African radio telescope of the AVN. This facility was commissioned at Kuntunse near Accra on August 24, 2017 as a functional radio astronomy telescope. The strategic location of the Ghana's 32m radio telescope of 5 degrees north of the Equator is attracting much interests especially in the global VLBI community in terms of spatial resolution contributions. Motivated by these developments, we aim at building a strong and vibrant Ghanaian research community in this area to operate and exploit the radio telescope in Ghana, the AVN, the SKA and other global astronomy instruments. In pursuit of this, research and development links are being established globally with pioneers in the field. The enthusiastic and interested young Ghanaian students and researchers are waiting to embrace opportunities to build carriers in this merging field in the country. The UK was first to heed to this call with the Development in Africa with Radio Astronomy (DARA) astronomy training programme with funding from the Royal Society and more recently by its Newton Fund. The DARA programme is highlighting the potential overlaps between the skills required for radio astronomy and those in related industries such as space science, satellite communications, telecommunications and big data applications. ESO joined the race last year with an outreach programme dubbed ESO-ART, which has had great impact on astronomy development in Ghana, and Sweden will probably move in soon.

In this presentation, I will speak about astronomy development in Ghana, the successes chopped so far and the way forward. I will as well, outline opportunities for research and development brought about by the emergence of astronomy in Ghana, and emphasize the impact of ESO-ART in Ghana's astronomy development drives.

Every globular cluster (GC) host stars with different light element abundances. These can be broadly classified in two populations: the first population (P1) has the same abundance as field stars of similar [Fe/H], while a second population (P2) shows abundance variations of some specific light elements like He, C, N, O, Na, Al and Mg. Here I’ll introduce the main idea behind the origin of the anomalous abundances of GC stars, and the challenges they face in the light of new evidence that have come up in the last two years.

The Hobby-Eberly Telescope (HET) is an innovative VLT, located at the McDonald Observatory. We have completed a major upgrade of the HET that has increased the pupil size to 10 meters and the field of view to 22 arcminutes by replacing the corrector, tracker, and prime focus instrument package. The wide field HET feeds a suite of four new and upgraded instruments, including the revolutionary integral field spectrograph, VIRUS, in support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). The HET Wide Field Upgrade has now been commissioned and is back in full science operations since mid 2016. I will discuss the upgrade, VIRUS and the other new instrumentation, and briefly present some early science results.

The talk will be delivered in two parts.  The first will summarise recent work on searches for any possible space-time variations in fundamental constants. Whilst results to date are suggestive (but inconclusive), the prospects for significantly improving existing measurements are good. We are about half-way through a large survey aimed at making the first 1000 high redshift measurements of the fine structure constant. The target timescale for completion is 2 years.We are also pushing to the highest possible redshifts with a smaller sample of quasars around z=6-7. I will discuss new results from that study.

The second half of the talk will focus on other aspects of cosmological anisotropy. In particular, I will describe a detailed exploration of the statistical properties of the Lyman alpha forest transmission using the SDSS survey. The results are surprising. Huge coherent structures in the HI distribution appear in the data over cosmological scales. The Cosmological Principle appears to reduce to an approximation on scales comparable to the Hubble length.

Almost forgotten, in the era of GPS/GLONASS/GALILEO, the art of astronomical navigation is still being practiced. I will introduce the tools: the sextant, the "Nautical Almanach", paper, preferably with polar coordinates and pocket calculator, a slide rule could do as well.

Starting from posing the problem, say how to sail from Tenerife to the Caribic, beauty and pitfalls of working with the sextant will be explained, including the artificial horizon. The measured altitude of celestial bodies then needs to be converted into crossing bearing lines. This leads to the graphic solution introduced as late as 1875 by French navy captain Marcq Saint-Hilaire. The method, btw. is a master piece how to design a highly efficient and numerically stable algorithm.

As a side issue, time permitting, the astronomical correction of the magnetic compass will shortly be touched.

The potential formation scenarios of early-type galaxies are very varied, from violent merger histories, to secular quenching scenarios. We use extended stellar kinematics (to ~4 effective radii) for ~25 galaxies from the SLUGGS Survey in an attempt to disentangle the effects of these histories on the kinematics of early-type galaxies. Additionally, we conduct JAM dynamical modelling using both radially-extended SLUGGS and central ATLAS3D data to construct the total-mass density profiles for these galaxies. A comparison of these results not only to other observations but also to the EAGLE and Magneticum simulations will be presented, to better understand the processes that are governing mass distributions in early-type galaxies.

The Serpens filament, as one of the nearest infrared dark clouds, is regarded as a pristine filament at a very early evolutionary stage of star formation. In order to study its molecular content and dynamical state, we mapped this filament in seven species including C18O, HCO+, HNC, HCN, N2H+, CS, and CH3OH. Among them, HCO+, HNC, HCN, and CS show self-absorption, while C18O is most sensitive to the filamentary structure. A kinematic analysis demonstrates that this filament forms a velocity-coherent (trans-)sonic structure, a large part of which is one of the most quiescent regions in the Serpens cloud. Widespread C18O depletion is found throughout the Serpens filament. Based on the Herschel dust-derived H$_{2}$ column density map, the line mass of the filament is 41±5Msun/pc, and its full width at half maximum width is 0.17±0.01 pc, while its length is ~1.6 pc. The inner radial column density profile of this filament can be well fitted with a Plummer profile with an exponent of 3.0±0.2, a scale radius of 0.037±0.002 pc, and a central density of (2.2± 0.1)e4 cm^{-3}. The Serpens filament appears to be slightly supercritical. The widespread blue-skewed HNC and CS line profiles and HCN hyperfine line anomalies across this filament indicate radial collapse in parts of the Serpens filament. C18O velocity gradients also indicate accretion flows along the filament. The velocity and density structures suggest that such accretion flows are likely due to the longitudinal collapse. Both the infall rate (~72 Msun/Myr, inferred from HNC and CS blue-skewed profiles) and the accretion rate (~10 Msun/Myr, inferred from C18O velocity gradients) along the Serpens filament are lower than all previously reported values in other filaments, indicating an earlier evolutionary stage.

The value of the Hubble constant, the present expansion rate of the Universe, remains a source of great interest in astrophysics today. The improved precision in local H0 measurements has revealed a 3.4σ discrepancy with the value inferred from observations of the cosmic microwave background under the assumption of a ΛCDM cosmology. The most precise local measurements of H0 currently rely on Cepheid variables to calibrate nearby Type-Ia supernovae. However, as Population II distance indicators, short-period, O-rich Mira variables can serve as a check to Cepheids while simultaneously increasing the local calibrating SN Ia sample. In this talk, I will present the results of a year-long, near-infrared Hubble Space Telescope observation of Mira variables in the megamaser host galaxy NGC 4258. I will discuss the process of discovering and characterizing Mira variables in the NIR for use as distance indicators.

Using images from Subaru and spectroscopy from Keck, the SLUGGS surveyaims to understand the formation and evolution of massive early-typegalaxies. For a sample of 25 galaxies, we probe the detailedkinematics and metallicities of their field stars to 3-4 effectiveradii and their globular clusters to 8-15 effective radii. From thesedata we have derived 2D maps of the halo stellar kinematics andmetallicity. We find changing kinematic signatures as we probe fromthe galaxy inner to halo regions.  Using JAM models we have derivedthe mass density slope and compare it to the latest cosmologicalsimulations. The SLUGGS survey has also collected over 4000 globularcluster radial velocities (the largest sample to date). From this datawe have derived the dynamical mass and dark matter fractions for ourgalaxies. We compare our results with the latest predictions from theIllustris simulations. We also explore the kinematics and scalingrelations of globular cluster systems. These results are placed in thecontext of two-phase galaxy formation. And if time allows, I willbriefly mention recent work on ultra-diffuse galaxies using the Kecktelescope.

Which mechanisms are mainly driving AGN activity is a major unsettled question. Thereby, the role of galaxy mergers is heavily debated, from both an observational as well as from a theoretical point of view. I will discuss different contradictory observational and theoretical results and present a study in which we investigated the statistical relevance of galaxy mergers for driving AGN activity, using large-scale cosmological hydrodynamic simulations from the Magneticum Pathfinder set. Our simulations predict that for luminous AGN at z=2, more than 50 per cent of their host galaxies have experienced a merger in the last 0.5 Gyr, consistent with a number of observational studies. These high merger fractions, however, merely reflect the intrinsically high merger rates of massive galaxies at z=2, in which luminous AGN preferentially occur. Apart from that, our simulations suggest that merger events are not the statistically dominant fuelling mechanism for nuclear activity over a redshift range z=0-2. Despite the statistically minor relevance of mergers, at a given AGN luminosity and stellar mass, the merger rates of AGN hosts can be up to three times higher than that of inactive galaxies. Such elevated merger rates still point towards an intrinsic connection between AGN activity and mergers, consistent with our traditional expectation.

Over the past few years, there has been enormous advances in understanding planet formation. The advent of extreme adaptive optics instruments, like SPHERE and GPI, produced a plethora of images of circumstellar disks in the act of producing planets.In this review, I take stock of what we have learned in recent years about

1) the mass budget available to make planets within10au from their host star and debris disks beyond 20au,

2) the directly imaged planets discovered beyond 10 au,

3) the shapes of debris disks resolved so far

4) the photometry of debris disks as a population

5) the rings and spirals in young circumstellar disks imaged with SPHERE and ALMA.

The current epoch holds science in high esteem. The belief that science and its methods have something particular seems to be very much shared. Qualifying a statement or a reasoning as scientific gives it sort of a merit or shows that we give it a particular trust. But, if science has something particular, what is it then?

(‘What is this thing called Science?’, Alan Chalmers, my translation)

To try and grasp the subtlety of this question, I will present and discuss the basis of three different science philosophies, which all have had a tremendous impact on how people considered the scientific activity at the time:

1/ ‘Induction’ promulgated by Sir Francis Bacon, the first modern science philosopher.

2/ ‘Falsificationism’, created by Sir Karl Popper to attack induction.

3/ I will conclude by presenting the structuralist theory of science by Thomas Kuhn, who created and popularized the now widely used term ‘paradigm shift’.

Recent ALMA observations are revolutionizing our understanding of protostellar disc appearance and evolution. This revolution is twofold: one the one hand, large and deep surveys are providing us with estimates of the main physical properties (such as dust mass and disc radii) of large homogeneous samples of discs; on the other hand, high resolution observations of individual discs are showing a completely unexpected richness in disc morphologies, including rings, spirals, horseshoes, cavities and shadowing effects. In this talk, I will show how can we model the observed properties of large disc samples (such as the Lupus and Chamaleon samples) in terms of simple disc population synthesis models, based on the simplest viscous evolutionary models available. At the same time, I will discuss how to reconcile the success of such simplified models (based on axisymmetric, power-law disc profiles in density, temperature and viscosity) with the apparent complexity of the observed morphology in individual sources.

The evolution of baryonic gas across redshifts is a powerful probe of several aspects of cosmology, galaxy formation and the epoch of reionization. Using a data-driven halo model to describe the distribution of neutral hydrogen (HI) in the post-reionization universe(z ~ 5 to 0), we obtain the best-fitting parameters from a rich sample of observational data: low redshift 21-cm emission line studies,intermediate redshift intensity mapping experiments, and higher redshift Damped Lyman Alpha (DLA) observations. Our model describes the abundance and clustering of neutral hydrogen across redshifts 0 - 5, and can be used to investigate several aspects of galaxy formation. I will describe extensions to the formalism for probing molecular gas at moderate redshifts and the epoch of reionization.

ν Pup is a 3rd-magnitude B8 IVe star. Spectroscopy has revealed two shell phases in a century, suggesting that the circumstellar disk, where the emission lines form, is viewed edge on but absent much of the time.

Photometry with the Hipparcos, SMEI, and BRITE satellites has found a persistent non-sinusoidal variability with period 1.52 d and semi-amplitude of 0.01-0.02 mag. Regular radial-velocity variations, if any, have an amplitude of no more than a few km/s on all relevant timescales.

The spectrum does not exhibit any pecularities, a magnetic field was not detected, and there is no indication of a companion star.

The 1.52-d period doesn't seem to be perfectly constant. In fact, the times of photometric maxima are periodically shifted back and forth by ±0.2 d with a period of 479 d. When folded with 479 d, the amplitude of the 1.52-d variability exhibits a double-wave modulation with unequal halfwaves.

1.52 and 479 are numerically unrelated (except that their ratio is 100.00065 π ...).

So far, so simple. However, we (DB, Thomas Rivinius / Paranal, Andrzej Pigulski / Wrocław, Despina Panoglou / Rio de Janeiro, and others) are struggling to put all facts under the common umbrella even of a simple toy model.

Therefore, after a brief introductory recap of the above facts, I’d like to use the meeting for a joint brain-storming exercise, hoping that your collective pressing our reset buttons can help us make progress. Many thanks in advance if you can come - if you can suggest a more convincing solution than the one that I’ll somewhat reluctantly present at the end, you’ll be invited to join the project as co-author.

The governance of file formats, protocols, and standards has recently emerged as a site of interest for both computer science and social science. Governed by an International Astronomy Union working group since 1982, over the last four decades, the FITS file format has become the de facto standard for sharing, analyzing and archiving astronomy data. FITS was widely adopted by the astronomical polity in the early 1980’s because of its ability to overcome the problem of incompatibilities between operating systems. Using the FITS format, an astronomer could share image files across operating systems using FITS as a common substrate. On the back of the original intent of FITS, astronomical data became both backwards compatible and easily shared.

However, new advances in astronomy instrumentation, computational technologies and analytic techniques have resulted in new data that do not work well within the traditional FITS format. Tensions have arisen between the desire to update the format to meet new data and analytic challenges and adherence to the original edict for FITS files to be backwards-compatible. The future of FITS is caught between the demands of rapidly changing technology and the insistence upon the stability of a rarely-changed format. We examine three inflection points in the governance of FITS: a) initial development and success, b) widespread acceptance and governance by the working group, and c) the challenges to FITS in a new era of increasing data and computational complexity within astronomy.

Planet host stars,  the Sun among them, will eventually evolve into giants to finally end their lives as white dwarfs. Planets will be engulfed along the giant phases, evaporated during the Planetary Nebula phase, and possibly destabilized when the star enters the white dwarf cooling track. A large number of  planets will eventually be destroyed and all  orbital configurations on the main sequences will be modified. Furthermore, the  planet surface conditions of those planets that survive are expected to change as well as the result of the evolution of the star.

I will discuss the limits that the theoretical studies allow us to set on the survival and habitability of planets as the star runs out of its hydrogen fuel. Finally, I will summarize the consequences that the presence and destruction of these Extreme Solar systems have in the evolution of stars.

Physicists believe they have made a huge progress in the concept of time since they have imported its ‘meaning’ into physics from the philosophers in the XVII century.

We understand time dilation in special and general relativity but still we have advanced enough in the notion of time-flow and the meaning of ‘present’.

I will introduce the nowadays hot debate among theoretical physicists according to which time has either disappeared from the equations, like in quantum gravity, or has become ‘fundamental and real’ and we need to re-write the physical laws.

In this last case: what if the the laws of physics were not timeless? What if they could evolve?

The characterization of the local double white dwarf (DWD) population is crucial to our understanding of multiple questions, from stellar evolution, through the progenitors of Type-Ia supernovae, to gravitational wave sources. From a spectroscopic sample of 439 WDs from the ESO-SPY survey, we measure the maximal changes in radial-velocity (DRVmax) between epochs, and model the observed DRVmax statistics via Monte-Carlo simulations, to constrain the population characteristics of DWDs. We then combine the results with those of a complementary sample from the SDSS to obtain new and precise information on the DWD population and on its gravitational-wave-driven merger rate. We find that ~10% of WDs are in DWD systems in the separation range ~<4AU within which the data are sensitive to binarity. The Galactic WD merger rate per WD is ~1e-11 per year. Integrated over the Galaxy lifetime, this implies that 8.5-11% of all WDs ever formed have merged with another WD. If most DWD mergers end as more-massive WDs, then some ~10% of WDs are DWD-merger products, consistent with the observed fraction of WDs in the 'high-mass bump' in the WD mass function, now possibly seen in Gaia DR2. The implied Galactic DWD merger rate is 4.5-7 times the Milky Way's specific type-Ia supernova (SN Ia) rate. If most SN Ia explosions come about from the mergers of some DWDs then ~15% of all WD mergers must lead to a SN Ia.

Massive stars, by which we mean those stars evolving through all the stable nuclear burning stages and eventually exploding as core collapse supernovae,play a fundamental role in the evolution of the Universe. In particular, a good knowledge of their evolution is required in order to shed light on many topical subjectslike the chemical evolution of the Universe, the UV outputs of the first stars, the properties of the Galactic and the Magellanic Clouds Wolf-Rayet stars, the origin of the Extremely Metal Poor stars, the final fate of massive stars and how they explode as core collapse supernovae of different types, the nature of the progenitors of the long Gamma Ray Bursts, the nature of the sources of gravitational waves.

In this talk I will review our current understanding of the life and death of massive stars, their contribution to the chemical evolution of the Universe and the nature of their remnants as a function of the initial mass, metallicity and rotation velocity.

The abundance of lithium in globular clusters stars is a valuable diagnostic to understand the self-enrichment processes occurring in the early life of these stellar systems. However, the abundance of lithium measured so far in globular cluster stars challenges the current theoretical models for the formation/evolution of GCs. We present new results concerning abundances of lithium and light elements involved in the chemical anomalies (usually observed in globular clusters) for the complex stellar system Omega Centauri.

Over the coming decade, our near-infrared spectroscopic view of galaxies and their environments will be greatly expanded with new instruments on the ground and in space. Beforehand, multi-aperture infrared spectrographs on 8-10m class telescopes have already given us a first assessment of the remarkable changes in the intrinsic properties of galaxies up to z ~ 3 as compared to the present day. With respect to our effort, I will give an overview of science results from FMOS-COSMOS, a NIR spectroscopic survey of 1500 emission-line (i.e., star-forming) galaxies at 1.4 < z < 1.7, and over a wide range in stellar mass, with the multi-fiber spectrograph FMOS on Subaru Telescope. Our sample is providing a characterization of the physical properties of the ISM at high-z including the metallicity, pressure, ionization, and dust content. Furthermore, the wide-area coverage of our survey is enabling us to study rare objects (dust-obscured starbursts, AGN), measure the large-scale environments of star-forming galaxies, and estimate the number density of bright Halpha emitters required for planning future cosmological tests. Finally, I will describe plans to further such studies at z > 1 and new science to be achieved with Subaru's Prime-Focus Spectrograph.

In this informal discussion we want to talk about the question of which results should be published where. We will give you an overview of the journals available for astronomers to publish their results. In particular we will present the recently reinvented AAS research notes, a journal for fast publication of small results, work in progress or null results. Furthermore, we will give an overview of the ESO publication guidelines. We will end with an introduction to open access journals and compare them with traditional journals.

Significative evidences of the role of the cosmic web in driving galaxy properties have been measured at low redshift from spectroscopic surveys.  They support a picture in which the influence of the geometry of the large-scale environment drives anisotropic tides which impacts the assembly history of galaxies. But extracting the cosmic web from observed datasets is still a challenge, in particular at high redshift where large and complete spectroscopic surveys are extremely costly. At these redshifts, though, we expect a stronger dependency of galaxy properties on the geometry of the accretion, which makes this extraction pivotal to understand galaxy evolution.

I will give a brief overview of the current status of cosmic web analysis from high redshift observations, either photometric data or lyman-alpha surveys. While relying on a pilot study in COSMOS and forecasts from the simulated horizon-AGN lightcone, I will show how the study of the co-evolution of galaxies and the cosmic web would be possible with future probes including LSST, Euclid, PFS and MOSAIC on the ELT.

Massive stars play an essential role in the Universe. They are rare, yet the energy and momentum they inject into the interstellar medium with their intense radiation fields dwarfs the contribution by their vastly more numerous low-mass cousins. During their formation, feedback from their intense radiation fields and magnetically launched, collimated protostellar outflows can limit their growth by accretion. In this talk, I will present a series of adaptive mesh refinement 3D radiation-hydrodynamics simulations of the collapse of initially turbulent, massive pre-stellar cores that include radiative feedback from both the direct stellar and dust-reprocessed radiation fields and outflow feedback from the accreting stars. We find that mass is channeled to the stellar system via gravitational and Rayleigh-Taylor (RT) instabilities through nonaxisymmetric disks and filaments that self-shield against radiation pressure while allowing for radiation to escape through optically thin regions. Inclusion of feedback from protostellar outflows punches holes in the ISM along the star’s polar directions, thereby increasing the size of optically thin regions where radiation can escape. This effect makes mass accretion via RT instabilities less significant. Furthermore, precession of the outflows due to the star being pushed around by the turbulent accretion flow cause the opening angles of the entrained material to increase with time. This effect, including the enhanced radiative heating by the escape of stellar radiation, further reduces accretion onto the massive star as compared to feedback from radiation alone. Our results suggest that disk accretion is therefore a requirement for the birth of massive stars, especially at late times.

The canonical model for the formation of terrestrial planets and giant planets cores relies on an early and very efficient phase of planetesimal growth in a gas-rich circumstellar disk. But, as theorists have known for decades now, there are some formidable obstacles to meeting that requirement, Many of these problems, and potentially their solutions, are associated with the growth, migration and especially the localizes concentration of "pebbles" (mm/cm-sized particles) in the first few million years of a disk's lifetime. That is fortuitous, since continuum emission from these particles in nearby disks can be readily detected and resolved with long-baseline radio interferometers like ALMA. In this talk, I will describe what we are learning about the evolution of solids from such data, including: (1) the signatures of particle growth and migration; and (2) the mounting evidence that small-scale substructures in the (gas) disk play fundamental - and perhaps mandatory - roles in the planet formation process.

The recent surge on neural-network based data modelling shows one thing: large data sets with Gaussian properties can be efficiently and scalably represented. How can we understand these models, why are they efficient, and why are we still no-where close to solving machine learning? What can and what cannot we do yet? I will try to sort some lines of thoughts, and goal discussing personal research topics which try to address the ‘cannot’s. And unfortunately lack the time to touch upon reinforcement learning and quantum computing, since those are even less solved.

Despite formidable challenges, comparative studies of exoplanet atmospheres have begun in earnest. Exoplanets caught in transit are particularly well suited for such investigations. I will discuss attempts to probe exoplanet atmospheres using high-precision photometric and spectroscopic observations. Our analysis of Kepler phase curves reveals peak brightness offsets in some cases, possibly indicating inhomogeneous clouds and/or substantial winds. We have also begun to extend studies using high-resolution transit spectroscopy to exoplanets in the sub-Saturn and super-Earth mass regimes. Finally, I will preview plans for using the NIRISS instrument on the James Webb Space Telescope, and other exciting opportunities for the near future.

The dust properties link to the star formation, the gas abundance, metallicity, and stellar mass and therefore it is fundamentally important to understand the evolutionary stage. Thus the characterization of this phase of the interstellar medium (ISM), best achieved in nearby galaxies, is crucial in the study of galaxy properties and their relationships with the environment in which reside. In this talk I will present scaling relations obtained in a sample of 1,630 nearby (z < 0.1) galaxies over a large range of stellar masses, SFR, and specific SFR (SFR per unit stellar mass, sSFR) with IR and sub-mm observations spanning the range from 12 to 850 microns.We find that the total infrared luminosity (Lir), the dust mass (Mdust) and the temperature of the cold dust component (Tc) form a plane that we refer to as the dust plane.

The scaling relations presented in this talk, besides providing a detailed view of the links and interplay between stars and ISM in galaxies, allow one to estimate fundamental parameters from limited observations and, therefore, represent an important resource for both using archival data in an efficient way and planning future observations. We also find the sSFR drives the position of galaxies on the dust plane: starburst (high sSFR) galaxies show higher Lir, higher Mdust and higher Tc compared to Main Sequence (typical sSFR) and passive galaxies (low sSFR). I will discuss my results in the general context of galaxy evolution and show possible future applications to the study of galaxies in dense environments and at higher redshifts.

A question frequently asked is: how reliable are the surface magnetic field observations of stars using the Zeeman-Doppler-Imaging (ZDI) technique? We approach this question by using highly resolved non-potential flux transport simulations as our point of reference. The simulations combine a flux transport model on the photosphere with a non-potential coronal evolution model using the magnetofrictional technique. We analyse the simulations of three different stellar models (a solar-like star and two more active stars) and model the Stokes profiles for ten different surface magnetic field maps per star. Stokes IV profiles were generated assuming an inclination angle of 60˚ and 20˚. To “observe” the simulation we use these simulated Stokes profiles as input for a ZDI code. We compared our sixty reconstructed ZDI maps with the large scale field of the input models in order to provide estimates for the reliability of the recovered field, with a particular focus on their toroidal and axisymmetric properties.

In the nearby Universe, double-barred galaxies account for 20% of all disc galaxies, this fraction being a lower limit due to the difficulties inherent to the detection of inner bars embedded within the central regions of structurally complex galaxies. Forming and sustaining two coexistent non-axisymmetric structures in a galaxy is a challenging problem not well understood yet with simulations nor with observations. The TIMER project (Time Inference with MUSE in Extragalactic Rings) is a well-designed survey of barred galaxies with noticeable central structures, such as inner bars and nuclear rings, which are considered as footprints of secular evolution. The current TIMER sample is composed by 24 galaxies, two of them being confirmed double-barred systems. In this Informal Discussion I will tell you about the effort we are making to retrieving the star formation histories of the TIMER galaxies, as well as the unprecedented results on the formation and stellar properties of double-barred galaxies.

Supernova driven outflows are thought to play a critical role in regulating the gas and baryonic content of galaxies. Most cosmological simulations rely on various prescriptions to generate these outflows that lack direct observational support due to their low surface brightness. However, these outflows can be constrained using background quasars line of sight passing near star forming galaxies. Using a combination of both MUSE and UVES instruments, we built the MusE GAs FLOw and Wind (MEGAFLOW) survey. We used the strong low-ionization MgII absorption to constrain the ejected mass rate using a bi-conical model. In this talk, I will present the results we have on these outflows from z~1 star-forming galaxies and compare them with simulation predictions.

The continuation of an incoherent discussion of emission by atoms and molecules in astrophysical plasmas. A quick recap of forbidden lines will be followed by a discussion diatomic molecules and recombination processes.

The growth of black holes and their role in quenching massive galaxies is a key unsolved problem in galaxy formation. I present a new suite of cosmological hydrodynamic simulations called Simba, which builds on our successful Mufasa simulations to include a novel torque-limited black hole accretion model and AGN feedback using observationally-constrained bipolar kinetic jets. I will describe the physical motivations behind our new model, explain why they represent an improvement over other current black hole growth and feedback models, and demonstrate that they yield a galaxy population in very good agreement with numerous observations across cosmic time. These successes set the stage for exploring galaxy--black hole co-evolution towards better understanding the impact of AGN feedback on the baryon cycle along the mass hierarchy.

I will review our recent results on the intrinsic three-dimensional  (3D) shape of bulges and bars in a statistically significant sample of galaxies from the CALIFA survey. Our work, based on the outcome of accurate multi-component structural decompositions of the galaxies, allow us to derive a probabilistic estimation of the 3D shape of individual structures, and it provides a new look at the secular evolution processes taking place in nearby galaxies.

We present a tomographic method allowing to recover the velocity field at different optical depths in a stellar atmosphere. It is based on the computation of the contribution function to identify the depth of formation of spectral lines in order to construct numerical masks probing different optical depths. These masks are cross-correlated with observed spectra to extract information about the average shape of lines forming at a given optical depth and to derive the velocity field projected on the line of sight. We applied this method to series of spectra of the red supergiant star mu Cep and derived velocities in different atmospheric layers. The resulting velocity variations reveal complex atmospheric dynamics and indicate that convective cells are present in the atmosphere of the mu Cep. The mu Cep velocities were compared with those obtained by applying the tomographic masks to series of snapshot spectra from 3D radiative-hydrodynamics CO5BOLD simulations.

Measurements of the CMB have driven our understanding of the universe and the physics that govern its evolution from primordial quantum fluctuations to its present state. They provide the foundation for the remarkable 6-parameter cosmological model, ΛCDM, which fits all cosmological data, although there are some tensions, which may provide hints at new physics. Far from being the last word in cosmology, the model raises deep questions: Is Inflation correct? What is its energy scale? What is the dark matter? What is the nature of dark energy? Are there additional light relic particles? The increasingly sensitive CMB observations being made to address these questions also provide powerful and unique probes of astrophysics. This talk will discuss recent experimental developments and observational results, primarily from the 10m South Pole Telescope (SPT), as well as the vision and planning for future CMB measurements, in particular CMB-S4.

We would like to share our manifold impressions and experiences from our recent trip to Ghana with you.

We will summarize our workshop with 40 Ghanaian students held at the University of Cape Coast, as well as the outreach activities we conducted in a fishing village and at the Ghana Planetarium in Accra (the only planetarium in sub-Saharan Africa outside of South Africa).

Furthermore, we would like to discuss the way forward for this initiative.

Disc galaxies at z~1 are known to be more clumpy and turbulent than their local counter parts. However, with the current observing facilitates, we are mostly limited to study these features at 1-2 kpc scales.  A way to overcome this issue before the new generation of telescopes becomes available, is to target strongly lensed objects. In this talk, I will show some of the results we obtained studying a representative sample of 8 strongly lensed galaxies at z~1, where spatial resolutions of a couple hundred parsecs can be reached. Using both MUSE and HST data we analysed the kinematics of these objects, focusing on the velocity dispersion of the ionised gas and their relationship with star-forming regions, providing some clues on local star-formation feedback at z~1.

IceCube has recently reported the discovery of high-energy neutrinos of astrophysical origin, opening up the PeV (10^15 eV) sky. These observations are challenging to interpret on the astronomical side and have triggered a fruitful collaboration across particle and astro-physics. I will first discuss neutrinos in an astronomical context. I will then make the case for extreme blazars, i.e. strong, very high energy gamma-ray sources of the high energy peaked type, to be the counterparts of at least some of the IceCube neutrinos. This scenario is supported by positional and energetic matches, theoretical modelling, and Monte Carlo simulations and has been confirmed very recently by the detection of gamma-ray emission from an extreme blazar within the error circle of an IceCube event. The talk is self-contained, requires no previous knowledge of neutrinos or blazars, and has been prepared for a very broad audience.

In this talk, I will present my work on two novel ways to map the Galaxy. The first one exploits a particular class of dark matter tracers - hypervelocity stars. These are stars observed in the halo with trajectories consistent with coming from the Galactic. My group has undertaken a comprehensive program to find them in the Gaia catalogue and model them in a full statistical framework to extract information on the mass and the shape of the Milky Way's halo. In addition, we are forecasting the ability of double white dwarfs to trace the Milky Way bulge and disc, when combining Gaia and LSST data with the future gravitational wave detections by the ESA mission LISA.

I will discuss the formation and dissipation of circumstellar disks around B-type emission line stars, and what we can learn from that in a wider context. A forming disk comes with a unique photometric signature constraining the absolute gas density and density law in the disk. When the time evolution of this signature is undisturbed by additional events, it allows to measure the viscosity in the disk, as it builds up and decays, as well as to constrain the mass and angular momentum losses from the star during such an event. Considering that Be stars are near critical rotators, the angular momentum loss from the star must be driven by the angular momentum transport from the evolving stellar core to the surface, and in this way Be stars may be used to calibrate stellar internal mixing theory well beyond its current limits.

Examining the chemo-morphological relations of stellar populations in the Milky Way (MW) bulge can provide clues to the formation history of our Galaxy, and of disc galaxies in general. To explore the possible disc origin of the MW bulge we use an N-body simulation in which the bulge forms secularly through the vertical heating of a bar, which in turn forms from a composite thin+thick disc. The simulation is compared to data of the bulge obtained with the near infrared spectroscopic survey APOGEE. As I will show, all the chemo-morphological relations examined are well reproduced by the model, as is the metallicity distribution function (MDF) of the MW bulge as a function of galactic longitude and latitude. These findings show that the chemical composition of the MW bulge is consistent with it being made up of thin+thick disc stellar populations. I will discuss these results in light of the mounting evidence -- from morphology, kinematics and chemistry -- of the MW bulge's pure disc origin.

The origin of these X-rays remain a mystery and only a handful of other stars displaying this phenomenon has been observed. The emission from the disk and the star vary on timescales from second to years and understanding these variations might provide an answer to the peculiar behaviour of disk formation and X-ray emission. I will give a more detailed description of the Be-stars in general and gamma Cas in  discuss some first results from time-series analysis using data from the SMEI satellite.

In the last decade a large effort has been dedicated to detect one of the last phase transitions in the Universe called the Epoch of Reionization and its preceding epoch know as the Cosmic Dawn, specially with the redshifted 21 cm probe. I will review the status of the various constraints that we currently have on reionization. I will also show the current results from a number of operating telescopes in the 2 meter wavelenght, a special attention will be paid to the recent results obtained from telescopes like EDGES and LOFAR.

We present the area of theoretical computer science called formal methods. We survey several ways how formal methods can help to ensure correctness of software. Further, we describe techniques for analysis of systems featuring probabilistic phenomena, where we do not rely only on simulations but rather on rigorous analysis and discuss their potential advantages.

Information field theory (IFT) provides probabilistic image reconstruction algorithms for incomplete and noisy data. Numerical information field theory (NIFTy) is a Python library for IFT algorithms. We provide a short introduction into the usage of NIFTy for astronomical data with a practice oriented demo, covering the Wiener filter and radio interferometric imaging. NIFTy is maintained by the IFT group at the MPI for Astrophysics and is available here: https://gitlab.mpcdf.mpg.de/ift/NIFTy

The centers of massive galaxies are special in many ways, not least because all of them are believed to host supermassive black holes. Since the discovery of a number of relations linking the mass of this central black hole to the large scale properties of the surrounding galaxy bulge it has been suspected that the growth of the central black hole is intimately connected to the evolution of its host galaxy. However, at lower masses, and especially for bulgeless galaxies, the situation is much less clear. Interestingly, these galaxies often host massive star clusters at their centers, and unlike black holes, these nuclear star clusters provide a visible record of the accretion of stars and gas into the nucleus. I will present our ongoing observing programme of the nearest nuclear star clusters, including the one in our Milky Way. Theses observations provide important information on the formation mechanism of nuclear star clusters. They allow us to measure potential black hole masses and might give a clue on how black holes get to the centers of galaxies.

The cold gas reservoir in galaxies determines their star formation rates over cosmic time. However, measuring the amount of cold gas in a large sample of galaxies was difficult in observation. Lack of observation constraints, the understanding of gas evolution from simulations and semi-analytic modeling is strongly limited. Fortunately, an alternative method of using dust continuum as an indirect proxy for cold gas has been developed during the last few years, and can be applied to thousands of galaxies that have (sub-)millimeter observations. Here I introduce our A3COSMOS project: mining the ALMA Archive Automatically in the COSMOS field. We exploited the full public ALMA archive in COSMOS in a systematic and automated way, with detailed photometry and extensive Monte Carlo simulation verifications. A3COSMOS aims at obtaining ALMA continuum photometry for each star-forming galaxy that falls into public ALMA pointings in COSMOS, and also detect any galaxy that is not in optical/near-infrared/radio prior catalogs. This pipelined exploitation will be regularly updated with ingesting more data as it becomes available. With ~650 currently well-constrained galaxies from 800+ high confidence ALMA detections, I present the properties of these galaxies and the newly measured evolution of gas fraction (gas-to-stellar mass ratio) and depletion time (=Mgas/SFR). I will demonstrate how galaxies’ spectral energy distributions and photometric redshifts can be much improved with our ALMA photometry, and how galaxies’ gas masses can be differed due to conversion methods, as well as how our new results can more tightly constrain the gas evolution compared to literature works.

Shell galaxies are understood to form through the collision of a dwarf galaxy with an elliptical galaxy. Shell structures and kinematics have been noted to be independent tools to measure the gravitational potential of the shell galaxies. We compare theoretically the formation of shells in Type I shell galaxies in different gravity theories in this work because this is so far missing in the literature.

We include Newtonian plus dark halo gravity, and two non-Newtonian gravity models, MOG and MOND, in identical initial systems. We investigate the effect of dynamical friction, which by slowing down the dwarf galaxy in the dark halo models limits the range of shell radii to low values. Under the same initial conditions, shells appear on a shorter timescale and over a smaller range of distances in the presence of dark matter than in the corresponding non-Newtonian gravity models. If galaxies are embedded in a dark matter halo, then the merging time may be too rapid to allow multi-generation shell formation as required by observed systems because of the large dynamical friction effect. Starting from the same initial state, in the dark halo model the observation of small bright shells should be accompanied by large faint ones, while for the case of MOG, the next shell generation patterns iterate with a specific time delay. The first shell generation pattern shows a degeneracy with the age of the shells and in different theories, but the relative distance of the shells and the shell expansion velocity can break this degeneracy.

The rational solution of the Monty Hall problem unsettles many people.Most people, including us, think it feels wrong to switch the initialchoice of one of the three doors, despite having fully accepted themathematical proof for its superiority. Many people, if given the choiceto switch, think the chances are fifty-fifty between their options, butstill strongly prefer to stick to their initial choice. Is there someratio behind these irrational feelings?

Galaxies continuously undergo chemical enrichment. Heavy elements are produced in stars and then dispersed into the interstellar medium by means of stellar winds and supernovae. Gas flows also contribute to regulate the amount of metals in the ISM; therefore, gas-phase metallicity represents a fossil record of the recent star formation history and is strongly sensitive to all the processes that drive the baryon-cycle in galaxies.

In this talk, I will first discuss the method for measuring chemical abundances in star forming galaxies, presenting a re-calibration of the most common metallicity diagnostics based on strong emission lines  by means of stacking galaxy spectra from the Sloan Digital Sky Survey according to their observed line ratios.

I will discuss also the evolution in the excitation properties and chemical abundances for a sample of high-redshift (1.2 < z < 2.5) gravitationally lensed sources, observed in the framework of the ESO Large Program KLEVER. Exploiting KMOS observations in the J, H and K bands we aim to map multiple optical rest-frame nebular diagnostics allowing a full, detailed characterisation of the ISM properties in these objects on a spatially resolved basis.

Description:Theoretical models of stellar evolution predict that most of the lithium inside a star is destroyed as the star becomes a red giant. However, observations reveal that about 1% of red giants are peculiarly rich in lithium, often exceeding the amount in the interstellar medium or predicted from the Big Bang. Here we report the discovery of 2,330 low-mass (1 − 3M) lithium-rich giant stars, which we show are consistent with internal lithium production that is driven by the tidal spin-up from a binary companion. Our sample reveals that most lithium-rich giants have helium-burning cores and that the frequency of lithium-rich giants rises with increasing stellar metallicity.

On ground-based telescopes employing adaptive optics (AO) systems, atmospheric dispersion compensation is essential to deliver high-quality imaging, and critical for coronagraphy and high-precision astrometry. In AO systems delivering high-Strehl, residual dispersion if often a dominant source of error, and is especially challenging to correct on large aperture telescopes. Imperfect compensation by atmospheric dispersion compensator (ADC) can be due to errors in the atmospheric dispersion estimation (usually derived from local temperature and pressure measurements), or calibration errors in the instrument and ADC optics. These limitations can be addressed with a high-precision on-sky measurement of residual dispersion in a closed-loop control scheme. In this work, we present a focal plane based technique, which utilizes the chromatic scaling of speckles to measure residual dispersion (atmospheric and optical) in the final science image. By using an adaptive speckle grid generated using a deformable mirror (DM) with a sufficiently large number of actuators, the residual dispersion is accurately measured and subsequently corrected in a closed-loop control. On-sky residual dispersion of < 1 mas across H-band was demonstrated, which reduced from 8.4 mas before closing the loop.

The detection of gravitational waves has opened a new era of scientific discovery, as it permits a new kind of observation of the cosmos, quite different from electromagnetic and particle observations. In this talk I will review the gravitational-wave signals detected up to now by LIGO and Virgo, and discuss the theoretical groundwork that allows to identify and interpret those signals. I will also highlight how those new astronomical messengers are unveiling the properties of the most extreme astrophysical objects in the universe and probe fundamental physics.

Jan Hendrik Oort:  75 years of passion for astronomy

Jan Hendrik Oort’s (1900-1992) professional life is part of the astronomical world heritage.

Part II will tell the most exciting stories of Oort’s research - the rotation of the Galaxy, the Crab nebula, the solar-system cloud of comets, and the boot strapping of radio astronomy - and delineate the links of his work to that of other famous astronomers of his time.

Fossil systems (FS) are groups or clusters of galaxies whose optical emission is dominated by a single giant galaxy. The lack of bright satellites is thought to be a sign of an evolved system, in which the central galaxy has had enough time to merge all the bright satellite population. At the same time, few interactions are expected within FS and the cosmic web. For these reasons, FS are considered fossil relics of the ancient Universe. However, this formation scenario has been questioned in recent years. In particular, controversial results were presented regarding X-ray and optical scaling relations, formation histories of the brightest central galaxies (BCGs), and the relaxation status of these systems.

In this seminar I will present some of the latest results from the Fossil Group Origins (FOGO) project. In the first part of the talk will be presented results on the satellite population: in particular, the dependence of the LF on the magnitude gap (the key parameter in the definition of FS) and one deep spectroscopic LF of a nearby (z=0.05) fossil group.

In the second part of the seminar, the attention will be focused on the BCGs of the two nearest-known FS (z=0.013 and z=0.025). I will present their resolved stellar populations and discuss their formation histories, trying to highlight the differences with BCGs in non-fossil systems.

Gravitational lensing allows us to weigh distant objects, measure cosmological distances, and get a super-resolved view of very distant sources. Its various regimes (strong lensing, weak lensing, microlensing and variations on these themes) have manifold applications in contemporary astrophysics.

In this mini-lecture, I will start with an overview of the basic principles and formalism, and some quick numbers for different astrophysical regimes. The second part of this mini-lecture will present a birdseye view of applications, somewhat biased towards topics that I have worked upon.

I will keep the formalism to a minimum. Links to more exhaustive materials will be provided with the slides.

The February 13, 2018 ESO NEWS Release eso1806 announced the first time use of the VLT combined four Unit telescope foci (thus making it the first 16-meter in existence!). It reminded me of the other 16-meter telescope which was being designed by National Optical Astronomy Observatory (NOAO) in the USA in the mid-1980’s under the name National New Technology Telescope (NNTT). Both VLT and NNTT use four 8-meter mirrors whose light was combined in both incoherent and coherent foci; the former had collecting diameters of 16 meter, the latter had resolution diameters of 22 meter (NNTT) and 130 meter (VLT/VLTI). I was involved in the design of both. Because of unfortunate circumstances the NNTT was cancelled in 1988, shortly after NOAO and ESO had agreed to coordinate their technological efforts. Following that I joined ESO in the implementation of the VLTI.

My talk will describe both efforts and the influence my earlier experience as Director of the Multi Mirror Telescope (MMT) affected both designs. That includes the inclusion of the Homothetic Beamcombiner referred to as the VLTI “Beckers Pit”. The talk will naturally involve much of my biography.

Stellar spectroscopy is becoming vitally important in many fields of modern astronomy. This method allows estimation of fundamental parameters of stars and their chemical abundances, the information crucial for studies of stellar physics, star - planet connection, structure and evolution of galaxies. Large surveys, like the Gaia-ESO and 4MOST, will deliver millions of spectra of stars from the most distant corners of the Milky Way. Next-generation facilities, like the E-ELT, will observe stars beyond tens of megaparsecs past the Local Group.

I will highlight some of the key advances in spectroscopy of cool stars, both from the observational and theoretical perspectives. New models of stellar atmospheres and spectra, which account for hydrodynamics and non-local thermodynamic equilibrium, make stars look different and turn classical concepts about stellar physics and Galactic  evolution upside-down. I will discuss how these developments impact our understanding of the Milky Way’s past, in particular, in relation to the emerging field of Galactoseimology, and present outlook for the future studies.

The VIMOS Spectroscopic Survey of a Supercluster in the COSMOS field (VIS3COS) aims to accurately map in 3D a superstructure at 0.8<z<0.9, which contains 3 massive X-rays confirmed clusters and shows a striking filamentary structure in the HiZELS Ha survey at z=0.84. The ~500 spectroscopic members probe a wide range of densities and environments (from fields to the cluster outskirts/rich groups).

In this talk, I will present this survey (Paulino-Afonso et al., A&A submitted) and our efforts to detail and understand the mass-environment relation, the nature of post-starburst galaxies and the role of mergers (Paulino-Afonso et al., in prep.). Mass or environment: which plays the key role? Can we witness the transformation of the blue sequence into the red sequence? If so, where is it more prominent: in the filaments, groups or clusters? Is this transformation also being encoded in the galaxy morphology? And what is happening to the interstellar medium pressure (or electron density)?

A long-standing question in galaxy evolution is how "red-and-dead" elliptical galaxies have been assembled. Thanks to the advancement of sensitive, wide-field near-infrared instruments in the past decade, we now know that such galaxies were already in place when the Universe was only a few billion years old. Their high stellar masses and low current star formation rates imply that they must have formed their stars very efficiently at z>2, and its star formation was rapidly shut down (“quenched”) thereafter. What is the physical process that quenches star formation at z~2? Active galactic nuclei feedback is the most commonly accepted interpretation, but its role in galaxy star formation remains controversial.

In this talk, I will review the evidence for early quenching in massive galaxies and the various quenching mechanisms proposed in literature. To address this decade-old puzzle, I will present new results from our multi-wavelength campaign of a sample of z~2 quiescent galaxies with ALMA, VLA and VLT, providing strong constraints on their stellar populations and interstellar medium.

When galaxies first form in a turbulent young Universe, they have diverse and complex morphologies. That has changed dramatically over the last 13 Gyr as elliptical and spiral shapes now dominate the bulk of local galaxy morphologies, as depicted by the Hubble diagram. The exact details of how and when these transformations happened still elude astronomers.

On this talk, I will show you a summary of our results on the evolution of galaxy structure across cosmic time (Paulino-Afonso et al. 2017, 2018). I will focus on the evolution of Ha and Lya emitting galaxies from z~0 to z~7 and contextualize this population of galaxies on the global picture of galaxy evolution.

Interstellar clouds, filling the space between stars, may be revealed thanks to either some spectral features originating in very rarefied gas or to the selective attenuation of the starlight, known as interstellar extinction. Selectivity means that a star, shining through a cloud or clouds is more red than intrinsically as the extinction is higher in blue range than in red. This is why extinction is nicknamed "reddening".

Extinction is being carried by dust particles of the submicron size. They are believed to be originated in vicinities of mass-loosing stars and then - to evolve in the interstellar space from bare to core-mantle ones.

However, grains, seen in any individual cloud, may be apparently seriously of different size, shape and chemical/cristalline composition. In a vast majority of cases one observes distant stars through several clouds, seeing thus an ill-defined average(s) which are very difficult to be interpreted in terms of any physical theory.

Currently I try, together with Ralf Siebenmorgen and Jonathan Smoker, to retrieve and compare extinction laws in several individual interstellar clouds.

A group of PhD students will present several different programs they use for spectroscopy of different kinds of stars and objects and will shortly describe their characteristics, use and advantages.

Extragalactic astrophysics suffers from an extreme case of time scale mismatch between human lives (1e2 years) and galaxies (1e8-9 years), making laboratory experiments impractical. In order to build a physics-based account of how galaxies formed and evolved together with their central supermassive black holes, we need to be able to forward model the processes involved.

I will present the ways in which my group attempts to do this using a combination of phenomenological models and artificial intelligence. I discuss how a large fraction of the behavior of black holes can be accounted for with a simple, near-universal distribution of accretion rates originating very close to the black hole, and how this fits into our understanding of how galaxies `turn off' their star formation. I also show how we can use new methods from artificial intelligence to extract more insight from existing data, and how we can use the for data-driven forward models of galaxy evolution. Finally, I outline how data-driven methods can push forward astrophysics in particular and science in general over the coming years.

Jan Hendrik Oort:  75 years of passion for astronomy

Jan Hendrik Oort’s (1900-1992) professional life is part of the astronomical world heritage.

Part I outlines Oort’s professional life with his seminal roles as founding father of radioastronomy in Europe and of a joint European optical observatory (ESO) as outstanding highlights.  It also gives an overview of the half dozen scientific fields which he influenced in a lasting fashion. These topics are nearly fully unrelated to one another, ranging from the solar system to the dynamics of the Milky Way and on to the large-scale structure of the Universe.  Oort’s achievements are interwoven into a unique network of 20th century astrophysics.  Very few people have similarly inspiringly combined unfiltered scientific curiosity with a firm, focused instinct for what is relevant and how it can be made bear fruit.

The evolution of the star formation activity and, thus, the assembly of the stellar content of galaxies remain at the heart of galaxy evolution studies. It is now rather well established that most galaxies form stars at a level, dictated mainly by their stellar mass and regulated by secular processes. This is seen as a Main Sequence (MS) in the Star `Formation Rate (SFR)-stellar mass plane. The normalization of this sequence declines with time since z~2, indicating an overall decrease of the star formation activity of the galaxy population in the Universe. However, we do not yet fully understand the processes that control this evolution, nor how individual galaxies evolve relative to it. While the existence of a MS may seem to suggest a simple and universal mode of star formation in galaxies (on average), the deviations indicate a more complex relation between galaxy SFRs, gas reservoir, external and internal mechanisms triggering or halting star formation. In this context I will show, with a statistical approach, how the MS evolves from the local Universe up to z~2 in slope and normalization, by using the deepest available UV and far-infrared galaxy surveys. In addition, I will discuss our results based on the Hubble Deep UV (HDUV) Survey about the interplay between environment, morphology and feedback in setting the distribution of galaxies around the MS at any redshift.

The rotation curve of the Galaxy is generally thought to be flat.However, using radial velocities of interstellar molecular clouds, which is common in rotation curve determination, seems to be incorrect and may lead to incorrectly inferring the shape of the rotation curve is flat. Tests, using photometric and spectral observations of bright stars as the rotation tracers are affected by motions of stars around local gravity centers and pulsation effects, seen in such early type objects, are difficult to betaken into account unless a lot of observing work is involved. I propose a method of studying the kinematics of the thin disc of our Galaxy outside the solar orbit in a way that avoids these problems. The proposed test is based on observations of interstellarCaII H and K lines which allow to determine both radial velocities and distances. The test was implemented using stellar spectra of thin disc stars at galactic longitudes of 135deg and 180deg. Using this method, I constructed the rotation curve of the thin disc of the Galaxy. The test leads to the obvious conclusion that the rotation curve of the thin gaseous galactic disk, represented by the CaII lines, is Keplerian outside the solar orbit rather than flat.

Throughout cosmic history, stars have been destroying deuterium and creating heavier elements. Generally, cosmological simulations include only the most abundant elements, such as oxygen and carbon, but there is much to be learned about our universe from other species. Neutron star mergers are rare, but last year's kilonova observations provided strong evidence that they produce copious amounts of rapid neutron capture (r-process) elements. It is still not clear how such rare events manage to efficiently enrich the interstellar medium, as inferred from observations of abundances in low-metallicity stars. In this talk, I will discuss cosmological zoom-in simulations of Milky Way-mass galaxies with explicit treatment of r-process enrichment via neutron star mergers. I will show that there is sufficient mixing to match current observational constraints and thus that our results are consistent with neutron star mergers being the source of most of the r-process nuclei in the Universe. Our new simulations also include slow neutron capture (s-process) enrichment via asymptotic giant branch stars, which traces mass loss by the old stellar population. I will show preliminary results on the relative importance of these two channels of neutron capture elements. I will end with a discussion on the deuterium abundance in the interstellar and intergalactic medium, which can be used to probe cosmology as well as the importance of stellar mass loss and thus the assembly history of galaxies.

We present several self-similar dynamic models for gravitational collapses in spherical and cylindrical geometries, respectively. Among others, we offer a solution to the luminosity problem (Kenyon et al. 1994) in protostar formation by a polytropic self-similar hydrodynamic model with variable central mass accretion rate (Gao & Lou 2017), advance a general polytropic dynamic model for the cold molecular cloud core Barnard 68 (Li, Lou, Esimbek 2017) in contrast to a static isothermal model of Alves et al. (2001), point out the incorrectness for the asymptotic density scaling of Tilley & Pudritz (2003) for an isothermal magnetohydrodynamic cylinder (Lou & Xing 2016), and derive the correct analytical asymptotic solution to replace the wrong asymptotic central free-fall solution of Kawachi & Hanawa (1998) for a conventional polytropic hydrodynamic cylinder in Lou & Hu (2017).

The discovery of the first exoplanet (Mayor & Queloz 1995) and the fast increasing subsequent detections raised the importance of accurate and precise determination of stellar parameters, since their characterization depend on them.

The effective temperature (Teff) is the most fundamental parameter, since it is required to derive other parameters such as mass and radius as well as measure chemical abundances.

Several studies have shown the existence of a correlation between the metallicity of the stars and the presence of planets (i.e. Fischer & Valenti 2005; Santos+2004). Some hypothesis has been proposed to explain this link, from a rich primordial cloud as a requisite to form planets (Pollack+1996) to stars increasing their metallicity by engulfment of planets (Laughlin & Adams 1997). Furthermore, a potential chemical signature as a trace of planetary formation have been proposed (Melendez+2009), for which identification, Teff's of unprecedented precision are required (10 K at most).

In this talk I will summarize my work in this context and the results of the first part of my research:

- The implementation of the methodology to derive accurate Teff's by fitting of observed and synthetic Halpha Balmer profiles. With it, errors associated to other techniques are circumvented, i.e. temperature-metallicity degeneracies and line-list selection (excitation and ionization equilibrium), reddening and photometry (InfraRed flux method).

- The accuracy of the theory at solar parameters is established and the reliability of HARPS spectra is checked.

The composition of cometary ices provides clues to the chemistry and conditions prevailing in theearly solar system. Since the detection of HCN at millimeter wavelengths in comet C/1973 E1 (Kohoutek), almost 30 molecules have been identified in cometary atmospheres from remote sensing observations from ground or from space platforms. Thanks to progresses in instrumentation and the availability of large telescopes, complex organic molecules have been identified. Measurements will be reviewed and the observed chemical diversity among comets will be presented. The relative abundances will be compared to values measured in star-forming regions to discuss the possible formation routes of cometary molecules. The talk will also include new findings about comet composition obtained from the Rosetta mission to comet 67P/Churyumov-Gerasimenko.

I will talk about a novel theory of dark matter superfluidity that matches the success of LCDM model on cosmological scales while simultaneously reproducing the MOND phenomenology on galactic scales.

Black holes are a fundamental ingredient in our current understanding of galaxy formation. In the absence of their feedback, state-of-the-art numerical simulations fail to match the observed properties of massive galaxies. Effectively, within a Lambda Cold Dark Matter Universe, black holes reconcile cosmology and galaxy formation theories by regulating baryonic processes. However, despite this widely-accepted and fundamental role, evidence of black hole regulated star formation remains elusive. I will present our observational efforts to characterize and understand the interplay between black hole activity and star formation, based on detailed stellar populations analyses. Our observations show that black hole and stellar population properties are tightly related, calling for a rich and complex observational framework where star formation, black holes, and chemical enrichment evolve coupled in time.

The hydrogen Lyman-alpha line is extremely important in many fields of astrophysics. In particular, this UV line is conveniently redshifted to the visible and near infrared wavelength ranges for high-redshift objects, making it observable from the ground. The hydrogen Lyman-alpha thus provides the main observational window on the formation and evolution of high redshift galaxies. However, this resonant line undergoes complex radiation transfer effects, which need careful modelling in order to extract information on the kinematics and geometry of the gas. This information is thus enclosed in the line shape. In this lesson I will briefly introduce the emission mechanisms for this line and explain the resonant scattering process.

Understanding the physics of galaxy formation is an outstanding problem in modern astrophysics.

Recent cosmological simulations have demonstrated that feedback by star formation, supernovae and active galactic nuclei appears to be critical in obtaining realistic disk galaxies and to slow down star formation to the small observed rates. However in particular physical processes underlying these feedback processes still remain elusive. In particular, these simulations neglected magnetic fields and relativistic particle populations (so-called cosmic rays). Those are known to provide a pressure support comparable to the thermal gas in our Galaxy and couple dynamically and thermally to the gas, which seriously questions their neglect.

After introducing the underlying physical concepts, I will present our recent efforts to model cosmic ray physics in galaxy formation. I will demonstrate that cosmic rays play a decisive role on all scales relevant for the formation of galaxies, from individual supernova remnants up to scales relevant for entire galaxies and even galaxy clusters.

I will introduce some results and on-going project of observing multiple transition isotopic lines of dense gas tracers toward nearby galaxies, which can help us to determine optical depth of dense molecular gas and other parameters.

Deriving accurate ages of stars is one of the most important, if elusive, goals of modern-day astrophysics.

In this talk, I will review some of the techniques that have been used to infer such ages, with emphasis on the oldest stars. Recent applications to stellar clusters and field stars alike will be critically discussed, as will the implications of this work for different areas of astrophysics.

We report new results from our study of the disk structure and evolution in the spiral protoplanetary disk hosting binary, HD 100453. This disk represents the only known “grand-design” (two-armed) spiral protoplanetary disk in which a low-mass companion has also been detected. We present the first constraints on the companion’s orbit, utilizing data from VLT/NACO, VLT/SPHERE, and Magellan/MagAO. We also constrain the disk inclination from ALMA 12CO observations and gas kinematic modeling. We find that the companion’s orbital semi-major axis (105±15 au) is 3-4 times greater than the observed extent of the disk, and that the companion orbits in the same plane of the disk to within measurable limits (±10º) on a low eccentricity orbit (e<0.3), in accordance with a classical disk truncation scenario. We utilized these constraints on the system geometry in combined hydrodynamic and radiative transfer simulations, and find in all cases that the companion generates a prominent two-armed spiral pattern in the simulated disk imaging that is in qualitative agreement with the observed disk structure. This system represents a benchmark in understanding the formation of spiral arms in protoplanetary disks, and has implications for on-going planet searches in the other two similar disks that do not host binary companions, but nevertheless host similar spiral structures.

The rich research program of the COMPASS experiment at CERN comprises the longitudinal and transverse spin structure of the nucleon and precision measurements with pions. The presentation will focus on low energy pi-photon interactions and diffraction production of light mesons addressing exotic states. The measurements allow quantitative comparisons with modern calculations using chiral effective field theory. The presentation will also address novel spectroscopic techniques for multi-hadron final states, reveal their analysis power and anticipates applications for future analysis of heavy mesons decays at B-factories.

The baryon cycle refers to the complex physical processes by which gas travels into, through, and out of galaxies. In this lecture, I will first review simulation and observational results which, together, have provided important fresh clues on the physics of galactic gas flows. I will then discuss prospects of detecting the circumgalactic medium in emission and other future progress which will likely impact galaxy formation studies at all cosmic epochs.

Understanding the evolution of baryonic mass at the centers of clusters is critical if we are to form a consensus on the evolution of structure. I will argue that while the growth and properties of Brightest Cluster Galaxies are becoming better understood through a range of surveys, the growth of the (hard-to-detect) intra-cluster light (ICL) is currently poorly constrained, despite the fact that the ICL makes up a significant fraction of the photospheric light in clusters. I will look at some of the challenges to ICL work using existing public survey pipelines, including HSC, and the techniques we have developed to overcome them. Finally, I will take a brief look at the prospects of similar science with the Large Synoptic Survey Telescope (LSST). With its unique combination of depth (five magnitudes deeper than SDSS) and area (20,000deg^2) LSST can reveal assembly histories of galaxies and the ICL with appropriate sky estimation techniques.

The most distant galaxies known are at z~10-11, observed 400-500 Myr after the Big Bang. The few z~10-11 candidates discovered to date have been exceptionally small— barely resolved, if at all, by the Hubble Space Telescope. In this talk I will present the discovery of SPT0615-JD, a fortuitous z~10 galaxy candidate stretched into an arc over 2.5” by the effects of strong gravitational lensing. Discovered in the Reionization Lensing Cluster Survey (RELICS) Hubble and Spitzer program, this candidate has a lensed H-band magnitude of 25.7 AB mag and lensing magnification of 4-7. The unprecedented lensed size of this z~10 candidate offers the potential for the James Webb Space Telescope to study the geometric and kinematic properties of a galaxy observed 500 Myr after the Big Bang. I will also present the sample of bright, lensed galaxy candidates at z>6 found in RELICS, that include other rare high-z arcs. Finally, I will discuss how we can improve our estimates of high-z SFRs by constraining the shape of the dust-attenuation law in individual galaxies.

Although there are promising explosion scenarios for explaining the observational attributes of thermonuclear supernovae, the calculated chemical structures vary on a wide scale. Constraining the chemical abundances in the supernova atmosphere could allow a powerful tool to test the different theories. Using the method of abundance tomography, we define a multi-layer synthetic atmosphere, where the fractions of the chemical elements are fitting parameters in each velocity shell. The modeling of the supernova spectra obtained at different epochs scans through the optically thin region of the atmosphere and provides the abundance distribution of the ejecta.Only a few studies based on abundance tomography were published, and Type Iax SNe were not the subject of this kind of analysis until now. The members of this subclass are peculiar thermonuclear explosions showing relatively low peak absolute brightness and low expansion velocities. Because of the wide range of physical properties, SNe Iax offer excellent possibilities to test different explosion scenarios. However, the high number of overlapping spectral features appearing even at early epochs challenges the abundance tomography technique.I present the first results on abundance tomography of Type Iax SNe carried out using the radiative transfer code TARDIS. I also discuss the assumed physical properties and the used fitting process regarding this peculiar class of supernovae. Finally, a possible correlation between the physical parameters and the abundance distribution is shown, together with an outlook on the possible progenitor scenarios.

The diversity of low-mass cluster galaxies in terms of their size and stellar content is striking. So-called ultra-diffuse galaxies residing in the core of a massive galaxy cluster appear surprisingly intact and might be protected by a large dark matter content. Ultra-compact objects, on the other hand, were proposed to be remnant nuclei of disrupted dwarf galaxies, but no tidal debris is found in their vicinity. The stellar age gradients of "normal" cluster dwarfs suggest that ram pressure stripping played an important role in their evolution - yet that alone cannot explain the systematically different angular momentum content of late-type and early-type dwarfs. In this talk I am going to present our latest observational efforts to tackle these problems,along with comparisons to simulations that can shed light upon the galaxies' evolutionary history.

Neutron stars are compact remnants of supernova explosions. They have radii of 10-15 km and masses comparable to that of the sun. One could expect neutron stars to be quiet, dead remnants of stellar evolution. Instead,they happen to produce most spectacular, extreme radiative phenomena. This talk will give a broad overview of neutron star activities and recent progress in understanding their mechanisms. Neutron stars generate powerful beams of coherent radio waves, pulsed high-energy gamma-rays, relativistic electron-positron winds, and giant X-ray flares. Some neutron stars live in binary systems and eventually merge, emitting strong gravitational waves and creating explosions observed from cosmological distances. Recent observational discoveries will be discussed, including the exciting detection of gravitational waves from a neutron star merger and its electromagnetic counterpart.

I discuss the rapid recent progress in microlensing, which is primarily driven by access to new instrumentation and facilities, including the new3-Telescope Korea Microlensing Telescope Network, and the 5-year dedicated Spitzer microlensing campaign.  New results include a turnover in the planet mass function for cold planets that is an order of magnitude more massive than for hot/warm planets, new limits and possible detection of free-floating planets, beginning probes of the Galactic distribution of planets and more.  Future advances in instrumentation, including high-resolution imaging at EELT and a dedicated WFIRST microlensing survey will open new possibilities.

The Magellanic Clouds are a nearby template for low-metallicity,gas-rich galaxies and thus represent an excellent opportunity to study star formation under conditions different from our Galaxy. Using near-infrared data from the VISTA Magellanic Cloud (VMC) survey we developed a method which identifies young stellar populations down to~1Msun. This opens the possibility to sample and characterize these populations across the low metallicity environment of the Magellanic Clouds. I will present the method and show the results we obtained from our pilot field (900 x 1260 pc), with a particular focus on pre main-sequence stars. We will discuss the distribution of the PMS population and analyze the revealed stellar structures. Finally, I will also compare the PMS distribution with the dust emission observed byHerschel and Spitzer.