paper

Angular momentum evolution of galaxies in EAGLE

arXiv:1609.01739 · doi:10.1093/mnras/stw2610

Abstract

We use the EAGLE cosmological hydrodynamic simulation suite to study the specific angular momentum of galaxies, , with the aims of (i) investigating the physical causes behind the wide range of at fixed mass and (ii) examining whether simple, theoretical models can explain the seemingly complex and non-linear nature of the evolution of . We find that of the stars, , and baryons, , are strongly correlated with stellar and baryon mass, respectively, with the scatter being highly correlated with morphological proxies such as gas fraction, stellar concentration, (u-r) intrinsic colour, stellar age and the ratio of circular velocity to velocity dispersion. We compare with available observations at and find excellent agreement. We find that follows the theoretical expectation of an isothermal collapsing halo under conservation of specific angular momentum to within %, while the subsample of rotation-supported galaxies are equally well described by a simple model in which the disk angular momentum is just enough to maintain marginally stable disks. We extracted evolutionary tracks of the stellar spin parameter of EAGLE galaxies and found that the fate of their at depends sensitively on their star formation and merger histories. From these tracks, we identified two distinct physical channels behind low galaxies at : (i) galaxy mergers, and (ii) early star formation quenching. The latter can produce galaxies with low and early-type morphologies even in the absence of mergers.

22 pages (16 without appendices). Accepted for publication in MNRAS. The only difference with previous version is a shorter abstract (to comply with the 250 words limit in MNRAS)

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