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Evolution of field early-type galaxies: The view from GOODS CDFS

Ferreras, I; Lisker, T; Carollo, CM; Lilly, SJ; Mobasher, B; (2005) Evolution of field early-type galaxies: The view from GOODS CDFS. ASTROPHYS J , 635 (1) 243 - 259. Green open access

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Abstract

We explore the evolution of field early-type galaxies in a sample extracted from the ACS images of the southern GOODS field. The galaxies are selected by means of a nonparametric analysis, followed by visual inspection of the candidates with a concentrated surface brightness distribution. We furthermore exclude from the final sample those galaxies that are not consistent with an evolution into the Kormendy relation between surface brightness and size that is observed for z = 0 ellipticals. The final set, which comprises 249 galaxies with a median redshift z(m) = 0.71, represents a sample of early-type systems not selected with respect to color, with similar scaling relations as those of bona fide elliptical galaxies. The distribution of number counts versus apparent magnitude rejects a constant number density with cosmic time and suggests a substantial decrease with redshift: n proportional to (1 + z)(-2.5). The majority of the galaxies (78%) feature passively evolving old stellar populations. One-third of those in the upper half of the redshift distribution have blue colors, in contrast to only 10% in the lower redshift subsample. An adaptive binning of the color maps using an optimal Voronoi tessellation is performed to explore the internal color distribution. We find that the red and blue early-type galaxies in our sample have distinct behavior with respect to the color gradients, so that most blue galaxies feature blue cores whereas most of the red early-types are passively evolving stellar populations with red cores, i.e., similar systems to local early-type galaxies. Furthermore, the color gradients and scatter do not evolve with redshift and are compatible with the observations at z 0, assuming a radial dependence of the metallicity within each galaxy. Significant gradients in the stellar age are readily ruled out. This work emphasizes the need for a careful sample selection, as we found that most of those galaxies that were visually classified as candidate early types-but then rejected based on the Kormendy relation-feature blue colors characteristic of recent star formation.

Type: Article
Title: Evolution of field early-type galaxies: The view from GOODS CDFS
Open access status: An open access version is available from UCL Discovery
Keywords: galaxies : elliptical and lenticular, cD, galaxies : evolution, galaxies : stellar content, COLOR-MAGNITUDE RELATION, HUBBLE-DEEP-FIELD, AGE-METALLICITY DEGENERACY, STAR-FORMATION EFFICIENCY, CCD SURFACE PHOTOMETRY, LDSS REDSHIFT SURVEYS, ELLIPTIC GALAXIES, STELLAR POPULATIONS, LUMINOSITY FUNCTION, FUNDAMENTAL PLANE
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/9494
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