Disk galaxies at z=2 in OWLS

TL;DR

This study uses cosmological simulations to analyze how supernova feedback influences the mass and angular momentum of disk galaxies at redshift 2, revealing a strong correlation between galaxy size and angular momentum that challenges common assumptions.

Contribution

It demonstrates that galaxy mass and angular momentum are tightly coupled at z=2, largely independent of feedback variations, providing new insights into galaxy formation models.

Findings

Galaxy mass and angular momentum are strongly coupled at z=2.

The ratio of galaxy to halo angular momentum correlates with galaxy mass.

Results suggest larger disk sizes at z=2 than predicted by some models.

Abstract

We use the OWLS (OverWhelmingly Large Simulations) set of cosmological Nbody/gasdynamical simulations to study the properties of simulated galaxies at z=2. We focus on the effect of supernova feedback from evolving stars on the baryonic mass and angular momentum content of galaxies that assemble at the center of 1e11-3e12 h^{-1}M_\odot halos. Our main finding is that the mass and angular momentum of such galaxies are strongly coupled, in a way that is approximately independent of feedback: varying the feedback implementation leads, in a given halo, to large variations in galaxy mass but leaves the galaxy mass-angular momentum correlation largely unaltered. In particular, the ratio between the angular momentum of a galaxy and that of its surrounding halo (j_d=J_gal/J_vir) correlates closely with the galaxy mass (expressed in units of the virial mass of the halo; m_d=M_gal/M_vir). This correlation differs substantially from the m_d=j_d assumption commonly adopted in semianalytic models of galaxy formation. We use these results to infer the sizes of disk galaxies at z=2 expected in the LCDM scenario and to interpret recent observations of extended disks at z~2 by the SINS collaboration