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Age-dating Stellar Populations of Luminous Red Galaxies

Published online by Cambridge University Press:  17 August 2012

Ando Ratsimbazafy ,
Catherine Cress ,
Steve Crawford ,
Claudia Maraston ,
Robert Nichol  and
Daniel Thomas
Ando Ratsimbazafy
Affiliation:
Physics Department, University of the Western Cape, Private bag X17, Cape Town 7535, South Africa
Catherine Cress
Affiliation:
Physics Department, University of the Western Cape, Private bag X17, Cape Town 7535, South Africa
Steve Crawford
Affiliation:
South African Astronomical Observatory, PO Box 9, Observatory 7935, Cape Town, South Africa
Claudia Maraston
Affiliation:
3Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby road, Portsmouth PO1 3FX, The United Kingdom email: raljha.a@gmail.com
Robert Nichol
Affiliation:
3Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby road, Portsmouth PO1 3FX, The United Kingdom email: raljha.a@gmail.com
Daniel Thomas
Affiliation:
3Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby road, Portsmouth PO1 3FX, The United Kingdom email: raljha.a@gmail.com
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Abstract

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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).

Keywords

galaxies: evolutioncosmology: cosmological parameterscosmology: observations
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 7 , Symposium S284: The Spectral Energy Distribution of Galaxies , September 2011 , pp. 265 - 267
Copyright
Copyright © International Astronomical Union 2012

References

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