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The Age-Redshift Relation For LRGs

Published online by Cambridge University Press:  17 July 2013

Gaochao Liu ,
Youjun Lu ,
Xuelei Chen ,
Yongheng Zhao ,
Wei Du  and
Xianmin Meng
Gaochao Liu
Affiliation:
Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China email: luyj@nao.cas.cn College of Science, China Three Gorges University, YiChang 443002, China email: gcliu@nao.cas.cn
Youjun Lu
Affiliation:
Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China email: luyj@nao.cas.cn
Xuelei Chen
Affiliation:
Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China email: luyj@nao.cas.cn
Yongheng Zhao
Affiliation:
Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China email: luyj@nao.cas.cn
Wei Du
Affiliation:
Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China email: luyj@nao.cas.cn
Xianmin Meng
Affiliation:
Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China email: luyj@nao.cas.cn
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Abstract

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The relative age of galaxies at different redshifts can be used to infer the Hubble parameter and put constraints on cosmological models. We select 23,883 quiescent luminous red galaxies (LRGs) from the SDSS DR7, dividing them into four sub-samples according to their velocity dispersions. Each sub-sample was further divided into 12 redshift bins. The spectra of the LRGs in each redshift and velocity bin were co-added. Adopting the GalexEV/SteLib model, we estimate the mean ages of the LRGs from these combined spectra by the full-spectrum fitting method and find it is consistent with the well known “downsizing” formation of galaxies. Based on the age–redshift relation, we further estimate the Hubble parameter.

Keywords

cosmological parameters – cosmology:evolution – galaxies:stellar content
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 8 , Symposium S295: The intriguing life of massive galaxies , August 2012 , pp. 179
Copyright
Copyright © International Astronomical Union 2013