Seminars and Colloquia at ESO Santiago

Gas-rich mergers represent a transformative phase in galaxy evolution and provide excellent laboratories for studying ISM properties in extreme star-forming environments. Their dusty nature requires spatially resolved, multi-wavelength observations for identifying the dominant power source and intrinsic energy distribution. I will highlight recent studies of local merger-driven starbursts using JWST and ALMA. These observations allow a comprehensive, extinction-free view of the gas and dust, revealing powerful multi-phase galactic outflows and intricate spatial variation in the dust and gas properties on sub-kpc scales.

During the asymptotic giant branch (AGB) phase, evolved stars
are shrouded in the gas and dust associated with their own mass loss.
The circumstellar envelopes that form via this process are molecularly
rich environments, many of which host SiO masers. As SiO maser pumping
mechanisms are not fully understood, there are many challenges in
relating maser activity to physical (circum-)stellar properties. I will
share results from the largest SiO maser survey, BAaDE, which detected
over 15000 SiO masers in the Milky Way plane with the VLA and ALMA. The
BAaDE database contributes to statistical studies of maser properties,
AGB properties, and Galactic dynamics. Beyond these statistical studies,
we also have a huge sample from which to draw exceptional maser sources.

Luminous quasars at high redshift (z ≳ 7) directly probe the build-up of supermassive black holes, the early galaxies hosting them, and the intergalactic medium during the epoch of reionisation. However, they remain difficult to find: their space density is low, they are faint in the observed frame, and they are vastly outnumbered by contaminants such as cool brown dwarfs. The Euclid mission is dramatically changing this picture: its large survey area, near-infrared depth, and wavelength coverage allow us to push the redshift frontier well beyond z ∼ 7. In this talk, I will describe how we are exploiting Euclid data within the Euclid Consortium and introduce our selection methods. I will focus on a novel machine-learning approach that combines generative, classification, and regression models, and show that it achieves high completeness and purity. I will then present first results from multi-wavelength follow-up observations of newly identified candidates, and conclude with my ongoing efforts to constrain the quasar luminosity function at z ∼ 7.5.

Over the past decades, advances in adaptive optics, coronagraphy, and data processing has enabled the direct detection and characterization of giant exoplanets orbiting young, nearby stars. The current generation of direct imagers, like the Gemini Planet Imager (GPI), have allowed us to detect and characterize planets much closer to their star than previous generations of instruments. In addition to the wealth of information about exoplanetary atmospheres we obtain from spectroscopy of directly imaged planets, the demographics of these planets allow us to directly test theories of planet formation, probing the outer reaches of these planetary systems. I’ll discuss how the combination of direct imaging with radial velocity and astrometry allows us to start building a unified demographic model of giant planet populations across all separations. This sets the stage for the next generation of direct imaging instruments, including the upgraded GPI 2.0, to map giant exoplanet demographics closer to the snow line, where most of these planets are expected to form.

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Planet-forming disks do not evolve in isolation but are often form in clustered environments where nearby massive stars can strongly alter their evolution through external photoevaporation. The closest laboratory to study these processes is the Orion Nebula Cluster. We present results from a VLT/MUSE Narrow Field Mode study of eight spatially resolved Orion proplyds. High spatial resolution integral-field spectroscopy reveals the detailed structure of these systems, including ionization fronts, irradiated disk surfaces, winds, and jets. Six targets show clear jet signatures, including outflows that remain poorly explored in the literature, while several emission tracers reveal distinct gas phases within the same systems. The rich MUSE wavelength coverage enables us to probe the kinematics and physical conditions of the emitting gas utilizing multiple ionic tracers, and to derive diagnostics of density, temperature, excitation, and chemical abundances across different proplyd components. These observations provide new constraints on how external irradiation affects disk dispersal, outflow activity, and the evolution of planet-forming material in massive star-forming environments.

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Accurately balancing gas reservoirs, star formation, and feedback across cosmic time remains a central challenge for galaxy formation models. In this talk, I will present a comparison of three state-of-the-art cosmological simulations: Magneticum, IllustrisTNG, and SIMBA, with recent observational constraints from MaNGA, eROSITA, and Sunyaev-Zel'dovich measurements. While reproducing the observed hot gas content of dark matter halos requires strong AGN feedback, such models often overquench star formation in galaxies. Conversely, weaker feedback better reproduces galaxy populations but systematically overpredicts the hot gas content of massive halos. I will discuss how these results reveal fundamental shortcomings in current AGN feedback prescriptions, suggesting that the challenge lies not only in the amount of energy injected but also in its timing, location, and coupling to the surrounding gas. These findings provide important guidance for the development of the next generation of galaxy formation models.

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Core-collapse supernovae are very energetic explosions that have a significant impact in the interstellar medium within galaxies. However, it is not well understood how progenitors of core-collapse supernovae form, evolve, and explode. In this talk, I plan to constrain the core-collapse supernova progenitor properties studying their star formation efficiency (or molecular gas depletion time) environments. In summary, it is found that interacting massive binaries occur in regions of intense, efficient star formation rather than simply higher gas content.

The past decade of observations of directly imaged companions has signaled a revolution in exoplanet spectroscopy. The objects observed to date reveal an extraordinary diversity of atmospheres, spanning a wide range of ages, temperatures, metallicities, and cloud properties. In this talk, I will present various results obtained with the numerical frameworks I am developing to model these complex exoplanetary spectra: ForMoSA and Optex. Using ForMoSA, I will discuss key atmospheric retrieval findings on benchmark targets (e.g., AF Lep b, beta Pic b, VHS 1256 b) alongside statistical studies of field brown dwarf spectral libraries. Specifically, I will address how these results help us piece together the broader picture of planet formation and evolution, particularly in contrast to stellar formation mechanisms and how formation pathways impact observable spectral features. Finally, I will conclude by outlining future prospects for the ELT era, highlighting end-to-end simulation work for MICADO's Long-Slit Spectroscopy (LSS) mode and its potential to further uncover the atmospheric properties of directly imaged exoplanets.

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