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9th of November 2016
ATNF Colloquium
The evolution of the angular momentum of galaxies in the EAGLE simulations
by Claudia Lagos (ICRAR/UWA)
Abstract. We use the EAGLE cosmological hydrodynamic simulation suite to study the specific angular momentum of galaxies, j, in the redshift range 0 < z < 3. Our aims are (i) to investigate the physical causes behind the wide range of j in galaxies at fixed mass at z=0 and (ii) examine whether simple, theoretical models can explain the seemingly complex and non-linear nature of the evolution of j in EAGLE. We find that j of the stars and baryons are strongly correlated with stellar and baryon mass, respectively, and that the dispersion of the relation is 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 present the most comprehensive comparison with available observations at z = 0 to date and find excellent agreement. Our findings in EAGLE suggest that in the case of all baryons and stars, j follows the theoretical expectation of an isothermal collapsing halo under conservation of specific angular momentum to within ~50%. When we focus on galaxies that are rotation-supported, the strong dependence of the baryon j on the neutral gas fraction is well described (at least at z < 2) by a simple model in which the disk angular momentum is just enough to maintain marginally stable disks. I will also show the main evolutionary tracks of the stellar j extracted from EAGLE and describe the catastrophic effect galaxy mergers have on it.

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