The ALeRCE (Automatic Learning for the Rapid Classification of Events) broker processes real-time astronomical alert streams from surveys like ZTF and the upcoming Rubin Observatory. To handle this scale and complexity, we’ve developed a progression of machine learning models: from Random Forests using hand-crafted features to deep learning approaches such as CNNs on image cutouts, multimodal transformers combining light curves with tabular metadata, and, most recently, vision transformers for modeling complex variability in a multi-survey scenario. While these models are trained on labeled datasets, deploying them in production involves additional challenges. In this talk, I will outline our algorithmic evolution, the gap between training and inference in real-world alert streams, and how we balance real-time performance and generalization in a system designed for scientific discovery at scale. Finally, I will highlight high-impact discoveries, such as changing-look AGNs, candidate pair-instability supernovae, and new cataclysmic variables, which often come from close collaborators leveraging simple services or identifying multimodal inconsistencies. This highlights a key lesson for Rubin: community adoption often begins with simple use cases and gradually enables complex, high-impact science across diverse astrophysical phenomena.

Star formation within galaxies is regulated by the circumgalactic medium (CGM) through gas inflows and outflows. I will present an analysis towards the multiphase (warm+cold molecular and ionized) gas and dust content toward a cool-core brightest cluster galaxy (BCG) at z=0.4, using JWST MIRI/MRS observations complemented by ALMA, MUSE, VLA, and Chandra data. The target harbours one of the largest known H2 reservoirs, elevated star formation, and an AGN. We obtained new JWST MIRI MRS observations that detect warm rotationally-excited H2 lines, PAH complexes, [Ar II], [Ne III] and [S IV] lines. The H2 line ratios indicate a different temperature distribution in the CGM compared to the interstellar medium within the BCG. The PAH complexes are found in dense clumps embedded within the more diffuse CGM along the radio emission, suggesting shock-driven star formation. I will discuss the implications of this pilot study on our understanding of higher redshift analogues, as well as the role of AGN feedback in regulating star formation. This case study serves as a pathfinder for using JWST to unveil the warm molecular gas in the circumgalatic medium for investigating the energy and mass flows in feedback processes.

Interstellar dust has a significant impact on many astronomical research fields, 

as it absorbs and scatters a large fraction of the star light, and influences star formation 

and galaxy evolution at all cosmic times. Understanding the amount of dust, the 

properties of the grains, and the interplay between dust and radiation, is thus 

crucial to derive precise knowledge of any object in the Universe that is obscured 

by dust, as well as to constrain the initial conditions for star and planet formation. 

My research focuses on understanding how dust grains of different sizes and compositions 

affect multi-wavelength observations. I am particularly interested in what dust particles are 

made of, how they evolve, and how they interact with radiation at different wavelengths.

In this seminar, I will explain which methods I use to study dust in the Milky Way, and what we 

have learned so far. I will also show how combining the results of these approaches, and the 

synergy between multi-wavelength data from the James Webb and the Hubble Space 

Telescopes, as well as other observations, is advancing our understanding of interstellar dust 

properties and how they vary in different environments.

Gamma rays offer a unique window into the most energetic phenomena in our Galaxy, 

where compact objects and explosive events drive powerful outflows. 

In this talk, I will explore how gamma-ray observations — particularly those from 

Imaging Atmospheric Cherenkov Telescopes (IACTs) like H.E.S.S. — have revealed 

the role of galactic compact sources in injecting energy and particles into their 

surroundings. I will focus on pulsars, microquasars, and novae as three example 

of high-energy outflows, discussing how their gamma-ray signatures inform us 

about particle acceleration, shock formation, and magnetospheric processes. 

I will also discuss the future of the field and which new pieces of the stellar evolution 

can we expect to find with the new generation of Cherenkov telescopes. . 

Since the first imaging observation of the Beta Pic disk in 1984, the astronomical community has thoroughly investigated this system, finding large amounts of dust and gas, exocomets, and two planets. All of this makes it the perfect laboratory to investigate the dynamics and chemistry of the late stages of planet formation. Recent JWST observations using imaging and spectroscopy have revealed that the dynamical activity of the system is much more complex than initially expected, with a high collision rate that affects the composition and the morphology of the disk. 

I will present here an overview of the system focusing on the results from JWST program GTO 1411, that was designed to investigate the dust component at near- and mid-infrared wavelengths, providing new insights on the dust morphology, composition, and distribution. The combination of the high sensitivity of the on board instruments with the 4QPM and Lyot coronagraphs allows for the most detailed images of the Beta Pictoris disk so far at this wavelength range, revealing new features and details in the dust distribution. In this talk, I will present JWST NIRCam and MIRI coronagraphic images, ranging from 1.82 to 23 microns. I will also summarize the analysis of prominent disk features observed for the first time, and compare it to previous ground and space based observations at multiple wavelengths. 

The chemical enrichment state and dust attenuation of galaxies, their redshift evolution, and their dependence on stellar mass, star formation rate, and environment are some of the most readily testable predictions of theoretical models of galaxy formation. The complex interplay between the processes that regulate chemical enrichment, including mergers, accretion, star formation, and feedback-driven outflows is expected to become simpler at early times and easier to model. Hence, high-z constraints on the gas-phase metallicity and dust attenuation of galaxies are crucial for informing the theoretical models. I will present these measurements based on a large compilation of JWST/NIRSpec data, containing more than 2,000 galaxies at 3 < z < 14. I will highlight established correlations, including the mass-metallicity relation and its redshift evolution, as well as the fundamental metallicity relation. Moreover, I will highlight new findings concerning the cosmic buildup of interstellar dust. The revolutionary combination of depth, wavelength coverage, and spatial resolution afforded by JWST has brought morphological and chemical analysis to the forefront of high-z studies. However, we are already facing the limitations of space telescopes: (i) their limited spatial resolution, and (ii) the high exposure times required to acquire deep high-spectral resolution spectra. I will discuss these shortcomings in light of the upcoming class of ELTs, and highlight the improvements expected in the coming decade.

Star formation regions in the solar neighborhood are the only places where we can resolve processes like gas cloud formation and dispersal, or stellar evolution, in great detail. The youngest stars found in active stellar nurseries are arguably the best tracers of their parent cloud motion. However, shrouded by gas and dust, they are missing from astrometric surveys like Gaia. To measure their motions and investigate the coupling to their natal cloud we instead have to turn to, e.g.,  infrared wavelengths. 
In this talk, I will first give an overview of the ESO public survey VISIONS, which aims to provide proper motions for embedded young stellar objects (YSOs), complimentary to Gaia. Then I will demonstrate the successful derivation of infrared YSO proper motions and investigation of the kinematics of stars and gas in a pilot study of the NGC 2024 cluster, located at d~400 pc in the Orion B molecular cloud. Lastly, I will offer an outlook on the broader context of star formation in the solar neighbourhood, using recent findings from the star formation group in Vienna.

Brown dwarfs have been extensively studied in nearby star-forming regions (d < 400 pc). However, theories suggest that high gas or stellar densities, as well as the presence of massive OB stars, may enhance brown dwarf formation relative to stars. To test this, it is crucial to study brown dwarf populations in massive young clusters, which provide dramatically different star-forming conditions. The nearest examples of such clusters are the supermassive star clusters (SSCs) Westerlund 1 and Westerlund 2, each exceeding 30000 Msun in total stellar mass.
As part of the EWOCS (Extended Westerlund 1 and 2 Open Clusters Survey) project, we have obtained deep JWST/NIRCam observations of these clusters. A key goal of this project is to derive their mass functions and assess whether extreme environments influence brown dwarf formation. By combining these results with studies of other massive young clusters led by members of the project, such as Trumpler 14 and RCW 38, we are placing the first robust constraints on the efficiency of brown dwarf formation in such environments.
In this talk, I will present the JWST/NIRCam data products of both clusters, the (sub)stellar initial mass function of Westerlund 1, and the detection and characterization of brown dwarfs in Westerlund 2, enabled by the rich multi-wavelength filter selection. I will also discuss the implications of these results for our understanding of star formation.

Active Galactic Nuclei (AGN) are among the most luminous and energetic objects in the Universe. Studying them is key to understanding the co-evolution of galaxies and their central supermassive black holes (SMBHs). At the same time, their brightness and ubiquity across cosmic time make AGN promising tools for cosmology. In this talk, I will explore the dual perspective of using AGN as cosmological probes while simultaneously refining our understanding of their physical properties. This two-way approach helps us progress on both fronts—learning more about the Universe while gaining deeper insight into AGN, their physics, and their evolution.  I will begin with the non-linear relation between the X-ray and UV luminosities of quasars. This correlation can be used to construct a Hubble diagram extending to redshift ~4, providing a way to test cosmological models. I will present recent results and discuss the tension this method reveals when compared with predictions from ΛCDM. I will then turn to AGN variability—particularly in the X-ray band—as a potential distance indicator. Data from current and upcoming observatories and surveys such as Euclid, NewAthena, and LSST, variability-based methods may provide a complementary approach to building the AGN Hubble diagram. Finally, I will focus on the potential of the BLR based geometric distances to derive the H0 constant by combining reverberation mapping and spectroastrometric measurements from GRAVITY. 

Our understanding of planet and star formation is mainly based on already formed planets around (sub-)solar-like stars. In this talk, I aim to broaden our perspective by focusing on protoplanetary disks around more massive stars, leveraging the special properties of their stellar interiors. In particular, convective sub-photospheric regions disappear during the pre-main-sequence evolution of stars with masses roughly between 1.5 and 4 Msun. In turn, the absence of convection influences the mixing of stellar material, the strength of the magnetic field, and consequently, the way disk material is accreted by the central stars. I will summarize our recent findings on the metallicity and accretion properties of intermediate-mass young stars in relation to disk structures, the potential presence of giant planets, and the size of their innermost orbits. I will conclude by presenting our ongoing efforts to reliably determine disk-to-star accretion rates of the most massive young stars with fully radiative envelopes.

Dusty star forming galaxies (DSFGs) are increasingly understood to be the primary contributors to the cosmic star formation rate density at least out to z~4 and sites of proto-cluster environments. We modeled the far-infrared and millimeter spectral energy distributions (SEDs) of 71 DSFGs selected at millimeter wavelengths by the Atacama Cosmology Telescope (ACT) with a lower flux density limit than previous catalogs of galaxies selected at the same wavelength. All candidates were cross-identified with detections in the Herschel SPIRE maps, and decomposed into possible multiple counterparts using a probabilistic cataloging (PCAT) algorithm. We obtained targeted observations of nineteen of our sources using the Submillimeter Array (SMA) telescope to acquire high resolution imaging and flux extraction to compare to the lower-resolution, single dish fluxes as well as assess the validity of the case for multiple components. In this talk, I will discuss the physical properties of the galaxies if they are treated as single sources with flux densities indicated by the single dish observations, but in this we exercise caution. ACT's lower flux limit, the PCAT decomposition, and the higher-resolution SMA observations all suggest that many of these DSFGs are likely to be unlensed and possibly multiples. I will then highlight the need for more efficient mapping of DSFG environments out to high redshift, and what the future may hold for unveiling the growth of structure through the (sub-)mm lens.

Selecting AGN candidates from photometric data, with the goal of spectroscopic follow-up, is a challenging yet essential task for spectroscopic surveys. In this study, we use a Random Forest classifier on photometric data from the Zwicky Transient Facility (ZTF) to identify AGN candidates. To target low-stellar-mass galaxies, we crossmatch these candidates with the NASA-Sloan Atlas (NSA) catalog, focusing on galaxies with stellar masses 𝑀∗<2×1010𝑀⊙. Using archival optical spectra from SDSS, we confirm the AGN nature of 357 (86%) out of 415 candidates through the presence of broad emission lines. Additionally, using data from eROSITA data release 1, we find that 67% of the candidates in the eROSITA-DE sky have an X-ray counterpart.

The last decade of observations of protoplanetary discs have shown a wealth of substructure including rings, gaps and spiral arms. Perhaps most intriguingly these observations also revealed the importance of the 3D structure of discs, where some discs are observed to have orientations that change as a function of radius or may also be broken. These so called 'warped discs' have challenged our understanding of disc evolution, and recent work has shown that these discs form a significant fraction of the disc population. In this talk I will discuss the connection between warped discs and the onset of planet formation, a major open question in planetary science.

Gamma-ray emission produced by interactions of cosmic rays with interstellar matter and radiation fields is a probe of non-thermal particles in galaxies. After decades of technological advancements in gamma-ray astronomy, several key results have significantly advanced our understanding of cosmic ray physics. However, there are still a few critical questions that remain unresolved. This review offers an overview of the current state of the field, while also exploring how next-generation gamma-ray facilities can further advance research in this area. Specifically, we will highlight the capabilities of the Cherenkov Telescope Array Observatory (CTAO). CTAO will be the first proposal-driven observatory in this energy range, providing science-ready data to the global research community.

Recent simulations of AGN feedback have found that the impact on the host galaxy’s gas changes during an AGN phase. Using radio-AGN that harbour bright jets, we can trace young and evolved AGN phases, and even multiple AGN phases in a single source. New and ongoing large area surveys like LoTSS (with LOFAR) and VLASS (with VLA), now make it possible to build large samples of radio-AGN and characterise their spectra. Combining this with optical spectroscopic surveys like SDSS and MaNGA can provide interesting insights into the link between the radio-AGN life-cycle and feedback. In this context, I will present our results on radio-AGN feedback on ionised gas, where we find evidence for [OIII] kinematics to be most disturbed during the young AGN phase (on average), which lasts for ~0.1-1 Myr after the AGN is triggered. We find that the feedback on [OIII] is intrinsically linked to the evolutionary stage of an AGN phase, irrespective of source luminosities, black hole and stellar masses, and accretion rates. I will then discuss the relative contribution of jets and radiation in low luminosity radio-AGN, combining LoTSS and MaNGA. Finally, I will briefly present our ongoing work on jet-ISM interaction in a high-redshift (z~3.5) radio-AGN.

An exciting new window into the circumgalactic medium (CGM) has opened up with the recent observations of the thermal and kinetic Sunyaev-Zel’dovich (SZ) effects on galactic spatial scales. I will present the ongoing efforts to extract these galaxy scales SZ signals in data from the Atacama Cosmology Telescope. I will show how these observations are currently being used to constrain important physical processes, like feedback, that govern galaxy formation. Additionally, I will present some puzzles these observations pose to state-of-the-art cosmological simulations. I will conclude by highlighting the expected rapid growth in such SZ
observations over the next decade with the upcoming millimeter and sub-millimeter focused experiments, like the Simons Observatory, CCAT, and CMB-S4.

Almost all accreting black hole and neutron star X-ray binary systems (XRBs) exhibit prominent brightness variations on a few characteristic time-scales and their harmonics. These quasi-periodic oscillations (QPOs) are thought to be associated with the precession of a warped accretion disc, but the physical mechanism that generates the precessing warp remains uncertain. Relativistic frame dragging (Lense-Thirring precession) is one promising candidate, but a misaligned magnetic field is an alternative, especially for neutron star XRBs. Here, I will present the discovery of 5 accreting white dwarf systems (AWDs) that display strong optical QPOs with characteristic frequencies and harmonic structures that suggest they are the counterpart of the QPOs seen in XRBs. Since AWDs are firmly in the classical (non-relativistic) regime, Lense-Thirring precession cannot account for these QPOs. By contrast, a weak magnetic field associated with the white dwarf can drive disc warping and precession in these systems, similar to what has been proposed for neutron star XRBs. The presented observations confirm that magnetically-driven warping is a viable mechanism for generating QPOs in disc-accreting astrophysical systems, certainly in AWDs. Additionally, they establish a new way to estimate magnetic field strengths, even in relatively weak-field systems where other methods are not available. And furthermore, I will discuss the possible new application of the model to explain mHz QPOs in Ultraluminous X-ray Sources (ULXs).

There is now a distinct possibility that neutral atoms and even molecules can exist in the extreme environments near the Supermassive Black Holes (SMBHs) that power the Active Galactic Nuclei (AGN), even in the absence of dust and the presence of strong UV/X-ray radiation fields. The corresponding spectral lines may yield  new spectral windows to AGNs as well as new tests of General Relativity in strongly curved Spacetimes.