南部非洲大型望远镜观测到的发光红星系
Age-dating Luminous Red Galaxies observed with the Southern African Large Telescope
摘要：
我们测量的值为宇宙膨胀$H(z) = 89 \pm 23$（统计）$\pm$ 44（系统）km s $^{-1}$ Mpc $^{-1}$在红移$z \simeq 0.47$的基础上的微分年龄技术。这种技术，也被称为宇宙计时器，使用两个红移之间的年龄差来计算宇宙的膨胀率。我们的测量是基于高质量的光谱分析的发光红星系（LRGs）获得的南部非洲大望远镜（SALT）在两个狭窄的红移范围的$z \simeq 0.40$和$z \simeq 0.55$作为初步试点研究的一部分。年龄是通过将单个恒星星族模型拟合到观测光谱来估算的。该测量是迄今为止在$z\sim0.5$通过该方法对$H(z)$的最佳估计之一。
英文摘要：
We measure a value for the cosmic expansion of $H(z) = 89 \pm 23$(stat) $\pm$ 44(syst) km s$^{-1}$ Mpc$^{-1}$ at a redshift of $z \simeq 0.47$ based on the differential age technique. This technique, also known as cosmic chronometers, uses the age difference between two redshifts for a passively evolving population of galaxies to calculate the expansion rate of the Universe. Our measurement is based on analysis of high quality spectra of Luminous Red Galaxies (LRGs) obtained with the Southern African Large Telescope (SALT) in two narrow redshift ranges of $z \simeq 0.40$ and $z \simeq 0.55$ as part of an initial pilot study. Ages were estimated by fitting single stellar population models to the observed spectra. This measurement presents one of the best estimates of $H(z)$ via this method at $z\sim0.5$ to date.
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