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arXiv · 1101.2423

The Majority of Compact Massive Galaxies at z~2 are Disk Dominated

Arjen van der Wel·Hans-Walter Rix·Stijn Wuyts·Elizabeth J. McGrath·Anton M. Koekemoer·Eric F. Bell·Bradford P. Holden·Aday R. Robaina·Daniel H. McIntosh
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Abstract

We investigate the stellar structure of massive, quiescent galaxies at z~2, based on Hubble Space Telescope/WFC3 imaging from the Early Release Science program. Our sample of 14 galaxies has stellar masses of M* > 10^{10.8} Msol and photometric redshifts of 1.5 < z < 2.5. In agreement with previous work, their half-light radii are <2 kpc, much smaller than equally massive galaxies in the present-day universe. A significant subset of the sample appears highly flattened in projection, which implies, considering viewing angle statistics, that a significant fraction of the galaxies in our sample have pronounced disks. This is corroborated by two-dimensional surface brightness profile fits. We estimate that 65% +/- 15% of the population of massive, quiescent z~2 galaxies are disk-dominated. The median disk scale length is 1.5 kpc, substantially smaller than the disks of equally massive galaxies in the present-day universe. Our results provide strong observational evidence that the much-discussed ultra-dense high-redshift galaxies should generally be thought of as disk-like stellar systems with the majority of stars formed from gas that had time to settle into a disk.

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Arjen van der Wel, Hans-Walter Rix, Stijn Wuyts, Elizabeth J. McGrath, Anton M. Koekemoer, Eric F. Bell, Bradford P. Holden, Aday R. Robaina, Daniel H. McIntosh. 2011-03-10. The Majority of Compact Massive Galaxies at z~2 are Disk Dominated. https://doi.org/10.1088/0004-637x%2F730%2F1%2F38

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