Seminars and Colloquia at ESO Garching and on the campus

Observations of protoplanetary disks (PPDs) and direct imaging of giant planets with spectra are providing increasingly strong constraints on the dust and gas properties in PPDs during planet formation. Meanwhile, large-scale numerical modeling of the joint dynamics of gas and dust in such disks has shown great progress over the past decade. In this talk, we will describe the new challenges emerging from observations and present the recent numerical studies in 3D global gas+dust two-fluid PPD simulations. We will use several examples to show how the interplay between disk global+local instabilities and the dust size evolution can impact the dust properties and distribution, both for interpreting observations, and ultimately, for understanding the planet formation.

The structure and evolution of the interstellar medium (ISM) strongly dictate galactic gas dynamics, star formation (SF), and galaxy evolution. While recent studies emphasize the rapid formation and destruction of molecular structures by stellar feedback, this conflicts with the observed deficiency of HI gas expected from such destruction. Here, I revisit the alternative paradigm: that molecular structures survive long-term and evolve primarily via galactic dynamics. Using ALMA observations of M83 and 12 nearby galaxies from the FACTS survey, I show that molecular cloud properties evolve alongside large-scale galactic structures. This is supported by correlations between environment, CO 2–1/1–0 line ratios, and cloud boundedness. Crucially, stellar feedback enhances CO ratios only near HII regions and fails to increase velocity dispersions, implying limited feedback-driven turbulence. Instead of undergoing rapid destruction, molecular clouds persist, coagulating and fragmenting via galactic dynamical processes. This framework shifts SF theory from the collapse of diffuse gas toward identifying triggers within long-lived clouds, potentially redefining galactic dynamics as a system governed by the motion of more discrete molecular structures rather than pure hydrodynamics.

Understanding when and how galaxies enriched their gas with heavy elements is key to reconstructing the physical conditions that shaped galaxy evolution, particularly during critical phases such as Cosmic Noon and the epoch of reionization. Thanks to ultra-deep JWST/NIRSpec spectroscopy from the MARTA survey, combined with an extensive high-redshift compilation, we explore chemical enrichment in >~600 star-forming galaxies at 1 < z < 6 with unprecedented detail. In particular, leveraging both direct electron-temperature measurements and newly calibrated strong-line diagnostics tailored to high-redshift ISM conditions, we build the most comprehensive and self-consistent view to date of the N/O-O/H optical-based relation beyond the local Universe. This large dataset reveals a mild but systematic nitrogen enhancement at Cosmic Noon, which is metallicity-dependent, with the largest offsets occurring at low metallicity. 

In addition, we investigate the abundance patterns of carbon, neon, sulfur and argon, providing complementary probes of different nucleosynthetic channels. While carbon and neon broadly follow the expectations from current chemical evolution models, argon and sulfur display unexpected trends with metallicity. These findings highlight the need for updated chemical evolution models and point toward a more complex interplay between star formation histories, stellar feedback, and the relative contributions of different nucleosynthetic sources in shaping the chemical enrichment of galaxies in the early Universe.

The field of black hole accretion is seeing a renaissance in the last 5–10 years, thanks to the advent of wide-field, time domain surveys across the electromagnetic spectrum. These surveys monitor hundreds of thousands of AGN at unprecedented cadence, revealing the secrets AGN were keeping while we weren’t watching. Time domain surveys are changing what we thought we understood about standard AGN activity, and thus, evolving our picture of how supermassive black holes grow and affect their environments. In this talk, I will present some recent highlights on supermassive black hole transients, like Tidal Disruption Events, and a new phenomenon called Quasi-Periodic Eruptions, which are a totally unexpected X-ray phenomenon, where ~million solar mass black holes show extremely high-amplitude regular flares, which have been posited as due to the presence of an orbiting stellar mass object (also known as Extreme Mass Ratio Inspirals). We will discuss the current state of the field, and implications for future joint detections with the NewAthena, LISA Gravitational Wave Observatory and other multi-messenger facilities.