Morphologies of Two Massive Old Galaxies at z ∼ 2.5

Abstract

We present the results of NICMOS imaging of two massive galaxies photometrically selected to have old stellar populations at z ∼ 2.5. Both galaxies are dominated by apparent disks of old stars, although one of them also has a small bulge comprising about one-third of the light at rest-frame 4800 Å. The presence of massive disks of old stars at high redshift means that at least some massive galaxies in the early universe have formed directly from the dissipative collapse of a large mass of gas. The stars formed in disks like these may have made significant contributions to the stellar populations of massive spheroids at the present epoch. © 2008. The American Astronomical Society. All rights reserved.