The buildup of the Hubble sequence in the cosmos field

Oesch, P A, Carollo, C M, Feldmann, R, Hahn, O, Lilly, S J, Sargent, M T and et al, (2010) The buildup of the Hubble sequence in the cosmos field. Astrophysical Journal Letters, 714 (1). L47-L51. ISSN 2041-8205

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Abstract

We use ~8600 COSMOS galaxies at mass scales >5e10 M sun to study how the morphological mix of massive ellipticals, bulge-dominated disks, intermediate-bulge disks, disk-dominated galaxies, and irregular systems evolves from z = 0.2 to z = 1. The morphological evolution depends strongly on mass. At M > 3e11 M sun, no evolution is detected in the morphological mix: ellipticals dominate since z = 1, and the Hubble sequence has quantitatively settled down by this epoch. At the 1011 M sun mass scale, little evolution is detected, which can be entirely explained by major mergers. Most of the morphological evolution from z = 1 to z = 0.2 takes place at masses 5e10-1e11 M sun, where (1) the fraction of spirals substantially drops and the contribution of early types increases. This increase is mostly produced by the growth of bulge-dominated disks, which vary their contribution from ~10% at z = 1 to >30% at z = 0.2 (for comparison, the elliptical fraction grows from ~15% to ~20%). Thus, at these masses, transformations from late to early types result in diskless elliptical morphologies with a statistical frequency of only 30%-40%. Otherwise, the processes which are responsible for the transformations either retain or produce a non-negligible disk component. (2) The disk-dominated galaxies, which contribute ~15% to the intermediate-mass galaxy population at z = 1, virtually disappear by z = 0.2. The merger rate since z = 1 is too low to account for the disappearance of these massive disk-dominated systems, which most likely grow a bulge via secular evolution.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
Depositing User: Mark Sargent
Date Deposited: 12 Sep 2013 15:02
Last Modified: 17 Mar 2017 06:10
URI: http://sro.sussex.ac.uk/id/eprint/46169

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