Speaker
Description
Almost all cosmological simulations of galaxy formation include the effect of photoionization and photoheating only via an homogeneous and redshift dependent Ultra Violet Background (UVB). While on large cosmological scales, the UVB can be approximated as homogeneous, on galaxy scales the high energy photon sources (stars, hot gas, black holes) are distributed highly non-uniformly. In zoom-in cosmological simulations, where only a small region of the universe is modeled with high resolution, it is worthwhile and computationally feasible to explore the effects of the non-uniform galactic UV source distribution on top of a metagalactic homogeneous UVB. In this talk I will discuss an implementation of the local photoionization radiation from young stars, post-AGB stars and hot halo gas, in the $N$-body SPH code Gasoline2. The simulated galaxies have been selected from the NIHAO suite. I will show how this physically-motivated feedback channel affects the evolution of the HI disks in terms of both global properties like total HI mass and disk extent, as well as small scale disk structure and dynamics, ultimately predicting how real galaxies will be seen by the upcoming exquisite radio facilities. Indeed I will show that the effect of the local radiation field starts to be visible in the galaxy structure only after $z \sim 1.5$, which is precisely the redshift range ($z=0$ to 1.5) where SKA and its precursors will probe the distribution of neutral gas in the universe at best.
| Wish list question? | 10. What do theoretical models predict about the origin and fate of HI in and around galaxies? |
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