The stellar evolution of luminous red galaxies, and its dependence on colour, redshift, luminosity and modelling

Rita Tojeiro, Will J. Percival, Alan F. Heavens, Raul Jimenez

Research output: Contribution to journalArticlepeer-review

Abstract

We present a series of colour-evolution models for luminous red galaxies (LRGs) in the seventh spectroscopic data release of the Sloan Digital Sky Survey (SDSS), computed using the full-spectrum fitting code vespa on high signal-to-noise ratio stacked spectra. The colour-evolution models are computed as a function of colour, luminosity and redshift, and we do not a priori assume that LRGs constitute a uniform population of galaxies in terms of stellar evolution. By computing star formation histories from the fossil record, the measured stellar evolution of the galaxies is decoupled from the survey's selection function, which also evolves with redshift. We present these evolutionary models computed using three different sets of stellar population synthesis (SPS) codes. We show that the traditional fiducial model of purely passive stellar evolution of LRGs is broadly correct, but it is not sufficient to explain the full-spectral signature. We also find that higher-order corrections to this model are dependent on the SPS used, particularly when calculating the amount of recent star formation. The amount of young stars can be non-negligible in some cases, and has important implications for the interpretation of the number density of LRGs within the selection box as a function of redshift. Dust extinction, however, is more robust to the SPS modelling: extinction increases with decreasing luminosity, increasing redshift and increasing r - i colour. We are making the colour-evolution tracks publicly available at http://www.icg.port.ac.uk/similar to tojeiror/lrg_evolution/.

Original languageEnglish
Pages (from-to)434-460
Number of pages27
JournalMonthly Notices of the Royal Astronomical Society
Volume413
Issue number1
DOIs
Publication statusPublished - May 2011

Keywords

  • surveys
  • galaxies: evolution
  • galaxies: stellar content
  • cosmology: observations
  • DIGITAL SKY SURVEY
  • INITIAL MASS FUNCTION
  • SPECTROSCOPIC TARGET SELECTION
  • STAR-FORMATION HISTORIES
  • LINE-STRENGTH GRADIENTS
  • GIANT BRANCH STARS
  • 7TH DATA RELEASE
  • TP-AGB MODELS
  • POPULATION SYNTHESIS
  • RADIATIVE OPACITIES

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