Hubble Space Telescope Imaging of the CFRS and LDSS Redshift Surveys. III. Field Elliptical Galaxies at 0.2<z<1.0
Date
1999
Authors
Schade, David
Crampton, David
Ellis, Richard
Le Fevre, Oliver
Hammer, Francois
Brinchmann, Jarle
Abraham, Roberto
Colless, Matthew
Glazebrook, Karl
Lilly, Simon
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Two-dimensional surface photometry has been performed on a magnitude-limited sample of 46 field galaxies that are classified as ellipticals based on two-dimensional fitting of their luminosity profiles using Hubble Space Telescope imaging. These galaxies are described well by a de Vaucouleurs R1/4 profile. The sample was selected from the combined Canada-France and LDSS redshift surveys and spans the redshift range 0.20<z<1.00. This analysis reveals several clear evolutionary trends. First, the relationship between galaxy half-light radius and luminosity evolves with redshift such that a galaxy of a given size is more luminous by ΔMB=-0.97+/-0.14 mag at z=0.92 relative to the local cluster elliptical relation. Second, the mean rest-frame color shifts blueward with redshift by Δ(U-V)=-0.68+/-0.11 at z=0.92 relative to the same relation in the Coma Cluster. These shifts in color and luminosity of field elliptical galaxies are similar to those measured for cluster ellipticals. Approximately one-third of these elliptical galaxies (independent of redshift) exhibit [O II] 3727 emission lines with equivalent widths >15 Å, indicating ongoing star formation. Therefore, field elliptical galaxies are not composed entirely of very old stellar populations. Estimated star formation rates (SFR) together with stellar population evolutionary models imply that <=5% of the stellar mass in the elliptical galaxy population has been formed since z=1. We find some evidence that the dispersion in color among field ellipticals at z~0.55 may be larger than that seen among samples of cluster ellipticals and S0 galaxies at similar redshift. We see no evidence for a decline in the space density of early-type galaxies with look-back time. Both the <V/Vmax> statistics and a comparison with local luminosity functions are consistent with the view that the population of massive early-type galaxies was largely in place by z~1. This implies that merging is not required since that time to produce the present-day space density of elliptical galaxies. However, the statistics are poor: a larger sample is required to produce a decisive result. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy Inc., under NASA contract NAS 5-26555.
Description
Keywords
cosmology: observations, galaxies: elliptical and lenticular, cD, galaxies: evolution, galaxies: fundamental parameters, galaxies: photometry - surveys
Citation
Collections
Source
Type
Journal article
Book Title
Entity type
Access Statement
License Rights
DOI
Restricted until
Downloads
File
Description