Speaker
Description
Galaxies are intimately connected to the environments they live in: they grow by accreting gas from the circumgalactic medium (CGM) and they heat and enrich the CGM through galactic outflows. Most cosmological, hydrodynamical simulations focus their computational effort on the galaxies themselves and treat the CGM more coarsely, which means small-scale structure cannot be resolved. I will discuss how we get around this issue by running zoom-in simulations of a Milky Way-mass galaxy with standard mass refinement and additional uniform spatial refinement (0.5 kpc) within the virial radius. The improved spatial resolution does not strongly impact the central galaxy or the average density of the CGM. However, it samples strong overdensities (and underdensities) much better and therefore drastically changes the radial profile of the neutral hydrogen column density. Additionally, we find that metals are mixed less efficiently, reducing the average metallicity of the (ionized) CGM. We conclude that some of the properties of the CGM are strongly resolution dependent, while others are more robust. Our results show that future observations with telescopes such as ASKAP, MeerKAT, and SKA are likely to detect more HI 21 cm emission than predicted by standard-resolution cosmological simulations.
| Wish list question? | 10. What do theoretical models predict about the origin and fate of HI in and around galaxies? |
|---|