Modelling the molecular gas content of galaxies is a highly non-linear, multi-scale problem in astrophysics. On one hand, it is necessary to simulate galaxies in realistic environments as they are affected by outflows and gas accretion from the cosmic web. On the other hand, molecular-cloud chemistry is regulated by conditions on sub-parsec scales. To overcome this challenge, we have developed a new sub-grid model, HYACINTH – HYdrogen And Carbon chemistry in the INTerstellar medium in Hydro simulations – that can be embedded into cosmological simulations of galaxy formation to calculate the non-equilibrium abundances of molecular hydrogen and its carbon-based tracers, namely, CO, C, and C⁺ on the fly. The model accounts for the unresolved density structure in simulations using a variable probability distribution function of sub-grid densities and a temperature-density relation. Included is a simplified chemical network that has been tailored for hydrogen and carbon chemistry within molecular clouds and easily integrated into large-scale simulations with minimal computational overhead. In this talk, I will introduce the sub-grid model, discuss its validation, and showcase its application to a simulated galaxy in post-processing.
(Cologne)

This talk will give an overview of the status of the FYST-telescope and the CCAT observatory, presently being shipped to be assembled on Cerro Chajnantor in Chile, and the role of Universität zu Köln within CCAT. I will address CCATs scientific goals, with emphasis on the research areas related to CRC 1601, and the first light and first generation of instrumentation, as well as the perspectives for future generations of instrumentation. In addition, I will elude on the  close collaboration with the Chilean scientific community in the context of CCAT, which also offers many opportunities for student exchange. (Cologne)

The Gaia mission is transforming our understanding of the Milky Way by delivering the most precise and comprehensive stellar catalog ever created. With over 2 billion sources, Gaia’s data holds the promise of unprecedented discoveries in astrophysics, from stellar evolution to the structure and dynamics of our galaxy. Gaia Data Release 3 (DR3) represented a major milestone, providing the most detailed view of our galaxy to date. Beyond high-precision astrometry and photometry, DR3 included radial velocities for millions of stars, detailed classifications of variable stars, astrophysical parameters, and even the largest catalog of binary systems. Additionally, DR3 introduced new insights into exoplanet-hosting stars, quasars, and the interstellar medium, broadening its impact across multiple fields of astrophysics. Looking ahead, Data Release 4 and 5 will mark another major leap forward, leveraging longer time baselines and unlocking the wealth of information contained in epoch-level data. In this talk, we will showcase some of the breakthroughs made possible by Gaia DR3 and present the exciting prospects for Gaia’s upcoming Data Releases.
(Cologne, Host Ronan Higgins)

tbd
(Cologne, Host Stefanie Walch-Gassner)

The intricate dynamics of molecular clouds, pivotal to the formation of stars, have been a subject of our ongoing investigation. In the SILCC-Zoom simulation suite, we investigate the formation and evolution of molecular clouds within their galactic, multi-phase ISM environment. The adaptive mesh refinement (AMR) magneto-hydrodynamics simulations include a chemical network and radiative transfer. 

The clouds are divided into coherent and hierarchical substructures using dendrograms. A detailed virial analysis of the identified substructures unravels their energetics. We can show that substructures that mostly consist of atomic, rather than molecular gas, are always unbound. Only denser, molecular structures become “bound”, but often they seem to be stabilized by ram pressure or thermal pressure rather than truly bound by self-gravity. Only a few structures are clearly gravitationally bound. Our results put the role of gravity to the test and have important implications for the low star formation rate and efficiency in molecular clouds.
(Cologne)

Picture Credit: Fig 3 from Ganguly, SW, + 2024, MNRAS, 528, 3630ff.