Age-dating Stellar Populations of Luminous Red Galaxies

We investigate the possibility of using Luminous Red Galaxies (LRGs) as “Cosmic chronometers” to measure the expansion rate of the universe to 3% over a redshift range 0.1 < z < 1.0. In this method, H(z) is directly measured by using the ages of passively evolving galaxies to determine dz/dt....

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Bibliographic Details
Published in:Proceedings of the International Astronomical Union 2011-09, Vol.7 (S284), p.265-267
Main Authors: Ratsimbazafy, Ando, Cress, Catherine, Crawford, Steve, Maraston, Claudia, Nichol, Robert, Thomas, Daniel
Format: Article
Language:English
Subjects:
Astronomy
Astrophysics
Contributed Papers
Cosmology
Evolution
Star & galaxy formation
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Summary:We investigate the possibility of using Luminous Red Galaxies (LRGs) as “Cosmic chronometers” to measure the expansion rate of the universe to 3% over a redshift range 0.1 < z < 1.0. In this method, H(z) is directly measured by using the ages of passively evolving galaxies to determine dz/dt. We first present results from our study of LRGs in simulations Crawford et al. where we explore the impact of extended star formation histories on the measurements of the Hubble parameter. We then extract a carefully selected sample of LRGs taken from Sloan Digital Sky Survey (SDSS) Data Released Seven (DR7), stack spectra in redshift bins to increase the signal-to-noise, and use the Lick index modelling presented in Thomas et al. to age-date the sample. We discuss the implications for expansion rate measurements and outline a proposal to observe LRGs with the Southern African Large Telescope (SALT).
ISSN:1743-9213
1743-9221
DOI:10.1017/S1743921312009222