Scientific Seminars
Cold molecular gas: scaling relations and powerful outflows
Bendix Hagedorn
Institute of Theoretical Astrophysics, University of Oslo
2025-02-21 11:00 Brera - Cupola Fiore + virtual room - https://meet.google.com/ehi-hpit-bzr
Cold molecular gas plays a key role in the evolution of galaxies by fueling star formation and AGN activity. We understand these processes in part through established statistical correlations between the molecular gas mass of galaxies and their star formation rate, stellar mass, and metallicities. These scaling relations are well constrained for massive, high-metallicity galaxies in the local universe, but not so for low-mass, generally metal poor galaxies. Analyzing the shape and scatter of key scaling relations for low mass galaxies can give insight into whether the physical processes governing star formation are systematically different in this regime, and what external factors drive galaxies onto different evolutionary paths. On the other side of the galactic baryon cycle, molecular gas is also present in galactic outflows. This is thought to be a key factor in the quenching of galaxies, their transition from actively star-forming to quiescent passive objects. Some of the most powerful outflows we observe are produced by ultra-luminous infrared galaxies (ULIRGs). In the local universe, these objects are the product of major mergers, and their kinematics, accordingly, are incredibly complex. In order to understand how much gas is removed by outflows, and whether this is sufficient to explain the quenching we observe, we need to carefully separate the outflowing gas from gas in Virial motion. In the complicated structure of ULIRGs, this process is challenging, but combining spatially resolved, multi-wavelength data opens new possibilities for physically motivated decompositions. |