1999MNRAS.309..208M -
Mon. Not. R. Astron. Soc., 309, 208-220 (1999/October-2)
The optical-infrared colour distribution of a statistically complete sample of faint field spheroidal galaxies.
MENANTEAU F., ELLIS R.S., ABRAHAM R.G., BARGER A.J. and COWIE L.L.
Abstract (from CDS):
In hierarchical models, where spheroidal galaxies are primarily produced via a continuous merging of disc galaxies, the number of intrinsically red systems at faint limits will be substantially lower than in `traditional' models where the bulk of star formation was completed at high redshifts. In this paper we analyse the optical-near-infrared colour distribution of a large flux-limited sample of field spheroidal galaxies identified morphologically from archival Hubble Space Telescope data. The I814-HK' colour distribution for a sample jointly limited at I814<23mag and HK'<19.5mag is used to constrain their star formation history. We compare visual and automated methods for selecting spheroidals from our deep HST images and, in both cases, detect a significant deficit of intrinsically red spheroidals relative to the predictions of high-redshift monolithic-collapse models. However, the overall space density of spheroidals (irrespective of colour) is not substantially different from that seen locally. Spectral synthesis modelling of our results suggests that high-redshift spheroidals are dominated by evolved stellar populations polluted by some amount of subsidiary star formation. Despite its effect on the optical-infrared colour, this star formation probably makes only a modest contribution to the overall stellar mass. We briefly discuss the implications of our results in the context of earlier predictions based on models where spheroidals assemble hierarchically.
Abstract Copyright:
1999, Royal Astronomical Society
Journal keyword(s):
galaxies: elliptical and lenticular, cD - galaxies: evolution - galaxies: formation - galaxies: photometry - infrared: galaxies
Simbad objects:
1
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