Special Colloquium
Dr. Sebastiano von Fellenberg	SCHEDULED

Max Planck Institute for Astrophysics, Garching

In this talk, I will review the current landscape of infrared observations of the Galactic Center, with a particular focus on three areas: (1) the accretion flow around Sgr A*, (2) the stars on the closest orbits around the black hole, which probe its mass and spin as well as the surrounding extended mass distribution, and (3) current and future observations of the nuclear star cluster as a whole. I will highlight recent advances in Galactic Center science enabled by JWST and GRAVITY+, and provide an outlook on what future observations with the ELT will reveal.

	Special Colloquium
Dr. Sougata Sarkar	SCHEDULED

Indian Institute of Science

Neutral atomic hydrogen (HI) is a powerful probe of the structure, dynamics, and interstellar medium (ISM) of galaxies. Its extended distribution and low velocity dispersion make it an excellent tracer of resolved kinematics, and hence of the gravitational potential, while the shapes of H I spectral profiles encode the thermal phases of the atomic gas. In this talk, I will present results from the GMRT ARChIve Atomic Gas Survey (GARCIA), based on spatially and spectrally resolved H I observations of 39 nearby galaxies. I will first discuss three-dimensional H I kinematic modelling and the resulting rotation curves. Combined with the stellar and gaseous components, these constrain mass models of the galaxies and the distribution of dark matter, allowing us to test the cusp-core problem. I will then explore the connection between baryons and dark matter through three galaxy scaling relations: the baryonic Tully-Fisher relation, the radial acceleration relation, and the stellar-to-halo mass relation. Moving from galaxy-scale dynamics to the atomic ISM, I will present a Gaussian Mixture Model (GMM) approach that clusters spectra with similar H I profiles across a velocity-resolved data cube. Averaging the spectra within each cluster boosts the signal-to-noise ratio (SNR), enabling more accurate Gaussian decomposition and estimates of the cold neutral medium (CNM) fraction. Together, these studies demonstrate how resolved H I observations connect the atomic gas with the baryonic and dark matter properties of nearby galaxies.

	Main Colloquium
Dr. Joop Schaye	SCHEDULED

Leiden University, The Netherlands

Hydrodynamical simulations of galaxy formation have become a central tool in extragalactic astronomy and cosmology. They underpin the interpretation of observations of galaxy evolution and provide predictions for cosmological surveys. I will discuss why their realism has improved dramatically in recent years, and where the main challenges remain. I will then introduce COLIBRE, a new suite of simulations designed to overcome several key limitations of earlier generations. COLIBRE explicitly models the multiphase interstellar medium, including the formation and evolution of dust grains. It suppresses the spurious transfer of energy from dark matter to baryons through dark matter super-sampling, and its largest volumes contain an order of magnitude more resolution elements than previous flagship runs. I will present a selection of first results on galaxy evolution across cosmic time. The simulations agree remarkably well with a wide range of observations over the full accessible redshift range, but they also reveal intriguing discrepancies that may point to gaps in our understanding of galaxy formation.