Cosmological Galaxy Formation Simulations Using SPH

TL;DR

This paper presents high-resolution SPH simulations of nine galaxies, incorporating detailed physics, and compares their properties with observations, highlighting successes and challenges in modeling realistic galaxy structures.

Contribution

First high-resolution SPH simulations of a diverse galaxy sample with detailed physics, analyzing their structural and kinematic properties against observations.

Findings

Simulated galaxies match observed color-magnitude and Tully-Fisher relations.

Central mass concentration is higher than observed, indicating feedback and resolution issues.

Merger history and halo spin influence disk formation.

Abstract

We present the McMaster Unbiased Galaxy Simulations (MUGS), the first 9 galaxies of an unbiased selection ranging in total mass from 5$\times10^{11}$ M$_\odot$ to 2$\times10^{12}$ M$_\odot$ simulated using n-body smoothed particle hydrodynamics (SPH) at high resolution. The simulations include a treatment of low temperature metal cooling, UV background radiation, star formation, and physically motivated stellar feedback. Mock images of the simulations show that the simulations lie within the observed range of relations such as that between color and magnitude and that between brightness and circular velocity (Tully-Fisher). The greatest discrepancy between the simulated galaxies and observed galaxies is the high concentration of material at the center of the galaxies as represented by the centrally peaked rotation curves and the high bulge-to-total ratios of the simulations determined both kinematically and photometrically. This central concentration represents the excess of low angular momentum material that long has plagued morphological studies of simulated galaxies and suggests that higher resolutions and a more accurate description of feedback will be required to simulate more realistic galaxies. Even with the excess central mass concentrations, the simulations suggest the important role merger history and halo spin play in the formation of disks.