Bibcode
Sales, Laura V.; Navarro, Julio F.; Schaye, Joop; Dalla Vecchia, C.; Springel, Volker; Booth, C. M.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 409, Issue 4, pp. 1541-1556.
Advertised on:
12
2010
Citations
144
Refereed citations
136
Description
We study the properties of simulated high-redshift galaxies using
cosmological N-body/gasdynamical runs from the OverWhelmingly Large
Simulations (OWLS) project. The runs contrast several feedback
implementations of varying effectiveness: from no feedback, to
supernova-driven winds to powerful active galactic nucleus (AGN)-driven
outflows. These different feedback models result in large variations in
the abundance and structural properties of bright galaxies at z= 2. In
agreement with earlier work, models with inefficient or no feedback lead
to the formation of massive compact galaxies collecting a large fraction
(upwards of 50 per cent) of all available baryons in each halo.
Increasing the efficiency of feedback reduces the baryonic mass and
increases the size of simulated galaxies. A model that includes
supernova-driven gas outflows aided by the energetic output of AGNs
reduces galaxy masses by roughly a factor of ˜10 compared with the
no-feedback case. Other models give results that straddle these two
extremes. Despite the large differences in galaxy formation efficiency,
the net specific angular momentum of a galaxy is, on average, roughly
half that of its surrounding halo, independent of halo mass (in the
range probed) and of the feedback scheme. Feedback thus affects the
baryonic mass of a galaxy much more severely than its spin. Feedback
induces strong correlations between angular momentum content and galaxy
mass that leave their imprint on galaxy scaling relations and
morphologies. Encouragingly, we find that galaxy discs are common in
moderate-feedback runs, making up typically ˜50 per cent of all
galaxies at the centres of haloes with virial mass exceeding
˜1011 M⊙. The size, stellar masses and
circular speeds of simulated galaxies formed in such runs have
properties in between those of large star-forming discs and of compact
early-type galaxies at z= 2. Once the detailed abundance and structural
properties of these rare objects are well established, it may be
possible to use them to gauge the overall efficacy of feedback in the
formation of high-redshift galaxies.