1999ApJ...525...31S -
Astrophys. J., 525, 31-46 (1999/November-1)
Hubble space telescope imaging of the CFRS and LDSS redshift surveys. III. Field elliptical galaxies at 0.2<z<1.0 (1).
SCHADE D., LILLY S.J., CRAMPTON D., ELLIS R.S., LE FEVRE O., HAMMER F., BRINCHMANN J., ABRAHAM R., COLLESS M., GLAZEBROOK K., TRESSE L. and BROADHURST T.
Abstract (from CDS):
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.
Abstract Copyright:
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Journal keyword(s):
Cosmology: Observations - Galaxies: Elliptical and Lenticular, cD - Galaxies: Evolution - Galaxies: Fundamental Parameters - Galaxies: Photometry - Surveys
Simbad objects:
47
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