Detection of evolved high-redshift galaxies in deep NICMOS VLT images

Citation
N. Benitez et al., Detection of evolved high-redshift galaxies in deep NICMOS VLT images, ASTROPHYS J, 515(2), 1999, pp. L65-L68
Citations number
35
Categorie Soggetti
Space Sciences
Journal title
ASTROPHYSICAL JOURNAL
ISSN journal
0004637X → ACNP
Volume
515
Issue
2
Year of publication
1999
Part
2
Pages
L65 - L68
Database
ISI
SICI code
0004-637X(19990420)515:2<L65:DOEHGI>2.0.ZU;2-C
Abstract
A substantial population of high-redshift, early-type galaxies is detected in very deep UBVRIJHK images. Four elliptical profile galaxies are identifi ed in the redshift range 1 < z < 2, with very red spectral energy distribut ions implying ages of greater than or similar to 2 Gyr for standard passive evolution. We also find later type IR-luminous galaxies at similarly high redshift (10 objects with z > 1, H < 25), with weak UV emission implying si ngle-burst ages of greater than or similar to 1 Gyr. The number and luminos ity densities of these galaxies are comparable to the local E/S0-Sbc popula tions for Omega(m) > 0.2, suggesting that the major fraction of luminous Hu bble sequence galaxies has evolved little since z similar to 2. A highly co mplete photometric redshift distribution is constructed to H = 25 (69 galax ies) that shows a broad spread of redshift, peaking at z similar to 1.5, in reasonable agreement with some analyses of the Hubble Deep Field. Four "dr opout" galaxies are detected at z approximate to 3.8 and are compact in the IR, similar to 0.5 kpc h(-1) at rest frame 3500 Angstrom. No example of a blue IR-luminous elliptical galaxy is found, thus restricting the star form ation epoch of elliptical galaxies to z greater than or equal to 5-10 for a standard initial mass function and modest extinction.