Cong Zhang, Han Zhang, Shuo Yuan, Tong-Jie Zhang, Yan-Chun Sun
By adopting the differential age method, we utilize selected 17832 luminous red galaxies (LRGs) from Sloan Digital Sky Survey Data Release Seven (SDSS DR7) covering redshift 0-0.4 based on `Carson & Nichol sample' to measure Hubble parameters. With single stellar population (SSP) models, we derive optimal age information of our selected sample. From the decreasing age-redshift relation, we obtain the new observational $H(z)$ data (OHD) points which are $H(z)=69.0\pm19.6 km s^{-1} Mpc^{-1}$ at $z=0.07$, $H(z)=68.6\pm26.2 km s^{-1} Mpc^{-1}$ at $z=0.12$, $H(z)=72.9\pm29.6 km s^{-1} Mpc^{-1}$ at $z=0.2$ and $H(z)=88.8\pm36.6 km s^{-1} Mpc^{-1}$ at $z=0.28$, respectively. Combined with other 21 available OHD data points, a good performance of constraint on $\Lambda$CDM model is presented.
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http://arxiv.org/abs/1207.4541
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