Friday, March 29, 2013

1303.6959 (Daniel Anglés-Alcázar et al.)

Cosmological Zoom Simulations of z = 2 Galaxies: The Impact of Galactic Outflows    [PDF]

Daniel Anglés-Alcázar, Romeel Davé, Feryal Özel, Benjamin D. Oppenheimer
We use high-resolution cosmological zoom simulations with ~200 pc resolution at z = 2 and various prescriptions for galactic outflows in order to explore the impact of winds on the morphological, dynamical, and structural properties of eight individual z = 2 galaxies. We present a detailed comparison to spatially- and spectrally-resolved H{\alpha} and other observations of z ~ 2 galaxies. We find that simulations without winds produce massive, compact galaxies with low gas fractions, super-solar metallicities, high bulge fractions, and much of the star formation concentrated within the inner kpc. Strong winds are required to maintain high gas fractions, redistribute star-forming gas over larger scales, and increase the velocity dispersion of simulated galaxies, more in agreement with the large, extended, turbulent disks typical of high-redshift star-forming galaxies. Winds also suppress early star formation to produce high-redshift cosmic star formation efficiencies in better agreement with observations. Sizes, rotation velocities, and velocity dispersions all scale with stellar mass in accord with observations. We find a diversity of morphological characteristics - among our two most massive galaxies, one resembles a quiescent grand-design spiral while the other is a clumpy disk undergoing a minor merger; the clumps are evident in H{\alpha} but not in the stars. Some galaxies have stellar densities above the threshold for compact ellipticals seen at these redshifts, although these galaxies are star-forming since we do not include quenching feedback. Rotation curves are generally slowly rising, particularly when calculated using azimuthal velocities rather than enclosed mass. These results show that cosmological simulations including outflows can produce disk galaxies similar to those observed during the peak epoch of cosmic galaxy growth.
View original: http://arxiv.org/abs/1303.6959

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