Speaker: Jindra Gensior (ICS, Zurich)
Title: The influence of the galactic gravitational potential on star formation and the interstellar medium
Abstract:
Recent observational studies indicate that approximately a quarter of early-type galaxies contain molecular gas, but exhibit strongly suppressed star formation rates compared to late-type galaxies with similar gas reservoirs. This is often attributed to a combination of a low gas fraction and low star formation efficiency (SFE). However, it remains unclear what drives the SFE decrease in massive galaxies. One proposed mechanism, morphological quenching, suggests that the global galactic environment can affect the gas dynamics such that star formation is heavily suppressed. I will present a suite of hydrodynamic simulations of isolated galaxies, which includes a sub-grid star formation model capturing the influence of galactic dynamics on the SFE via the virial parameter of the gas. The parameter space spanned by these simulations ranges from disc galaxies to spheroids, with initial gas fractions between 1 and 20%. This enables a detailed exploration of how differences in the gravitational potential/morphology change the properties of the gas and the SFE, as well as how it interlinks with the gas fraction. I show that the shear generated by the deep gravitational potential of bulges can suppress star formation, especially in the central region of galaxies, by altering the dynamical state of the gas and rendering it super-virial. This "dynamical suppression" of star formation is enhanced at higher central stellar surface densities and lower gas fractions. Furthermore, I demonstrate that the resultant ISM properties (e.g. morphology, velocity dispersion) are also strongly affected by gas fraction and galaxy potential. In the last part of my talk, I will present the EMP-Pathfinder simulation suite of cosmological zoom-ins of Milky-Way mass galaxies to add the perspective of galaxies evolved across cosmic time to the previously presented work and give an outlook on my current project @UZH, investigating the HI content of (simulated) galaxies.