1305.6931 (Yu-Yen Chang et al.)

Structural Evolution of Early-type Galaxies to z=2.5 in CANDELS    [PDF]

Yu-Yen Chang, Arjen van der Wel, Hans-Walter Rix, Bradford Holden, Eric F. Bell, Elizabeth J. McGrath, Stijn Wuyts, Boris Häußler, Marco Barden, S. M. Faber, Mark Mozena, Henry C. Ferguson, Yicheng Guo, Audrey Galametz, Norman A. Grogin, Dale D. Kocevski, Anton M. Koekemoer, Avishai Dekel, Kuang-Han Huang, Nimish P. Hathi, Jennifer Donley

Projected axis ratio measurements of 880 early-type galaxies at redshifts 11 early-type galaxies show a variety of intrinsic shapes; even at a fixed mass, the projected axis ratio distributions cannot be explained by random projection of a set of galaxies with very similar intrinsic shapes. However, a two-population model for the intrinsic shapes, consisting of a triaxial, fairly round population, combined with a flat (c/a~0.3) oblate population, adequately describes the projected axis ratio distributions of both present-day and z>1 early-type galaxies. We find that the proportion of oblate vs. triaxial galaxies depends both on the galaxies stellar mass, and - at a given mass - on redshift. For present-day and z<1 early-type galaxies the oblate fraction strongly depends on galaxy mass. At z>1 this trend is much weaker over the mass range explored here (10^101, compared to 0.20+-0.02 at z~0.1. In contrast, the oblate fraction among low-mass early-type galaxies (log(M*/M_sun)<10.5) increased toward the present, from 0.38+-0.11 at z>1 to 0.72+-0.06 at z=0. [Abridged]

View original: http://arxiv.org/abs/1305.6931