论文标题
在$ z = 1.754 $：延迟时间分布的启示的含义GRB181123B的光学余辉和主机星系的发现
Discovery of the optical afterglow and host galaxy of short GRB181123B at $z =1.754$: Implications for Delay Time Distributions
论文作者
论文摘要
我们介绍了{\ it swift}短期伽马射线爆发的光学余辉和主机星系的发现，Grb \，181123b。爆发后，双子座 - 北的观察结果约为$ \ 9.1 $ 〜HR，显示出微弱的光学余声，$ i \ i \大约25.1 $ 〜mag，其角度偏移为0.59 $ \ pm $ 0.16 $''$'$''$''$'$''$''$''$''$''$'''''$''''''''$''$''$''''''''''''''''''''从其主机的银河系中。使用$ grizyjhk $观测值，我们测量主机银河系的光度红移为$ z = 1.77^{+0.30} _ { - 0.17} $。从跨越4500-18000〜Å的主机星系的双子座和凯克光谱的组合，我们检测到13390〜Å的单个发射线，推断为h $β$ at $ z = 1.754 \ pm 0.001 $，并证实了光度恢复。 The host galaxy properties of GRB\,181123B are typical to those of other SGRB hosts, with an inferred stellar mass of $\approx 1.7 \times 10^{10}\,M_{\odot}$, mass-weighted age of $\approx 0.9$~Gyr and optical luminosity of $\approx 0.9L^{*}$.在$ z = 1.754 $，GRB \，181123b是带有光学余波检测的最遥远的安全SGRB，而在$ z> 1.5 $中仅有的三个。在越来越多的高$ z $ sgrb的动机中，我们探讨了缺少$ z> 1.5 $ sgrb总体在延迟时间分配模型上的{\ it swift swift}样本中的效果。我们发现，平均延迟时间为$ \ 4-6 $ 〜GYR的对数正态型模型与观察到的分布是一致的，但可以将$ \ \ y of $ z> 1.5 $恢复。相比之下，具有$ \ propto $ $ $ t^{ - 1} $的幂律模型与红移分布一致，并且在这些红移中最多可容纳$ \ of $ \ of $ \ of $ \ of。在此模型下，我们预测$ \ \ \ 1/3 $的当前{\ it swift} sgrbs总体为$ z> 1 $。现有高级SGRB的未来发现或恢复将为其延迟时间分布以及其编队渠道提供重要的区分功能。
We present the discovery of the optical afterglow and host galaxy of the {\it Swift} short-duration gamma-ray burst, GRB\,181123B. Observations with Gemini-North starting at $\approx 9.1$~hr after the burst reveal a faint optical afterglow with $i\approx25.1$~mag, at an angular offset of 0.59 $\pm$ 0.16$''$ from its host galaxy. Using $grizYJHK$ observations, we measure a photometric redshift of the host galaxy of $z = 1.77^{+0.30}_{-0.17}$. From a combination of Gemini and Keck spectroscopy of the host galaxy spanning 4500-18000~Å, we detect a single emission line at 13390~Å, inferred as H$β$ at $z = 1.754 \pm 0.001$ and corroborating the photometric redshift. The host galaxy properties of GRB\,181123B are typical to those of other SGRB hosts, with an inferred stellar mass of $\approx 1.7 \times 10^{10}\,M_{\odot}$, mass-weighted age of $\approx 0.9$~Gyr and optical luminosity of $\approx 0.9L^{*}$. At $z=1.754$, GRB\,181123B is the most distant secure SGRB with an optical afterglow detection, and one of only three at $z>1.5$. Motivated by a growing number of high-$z$ SGRBs, we explore the effects of a missing $z>1.5$ SGRB population among the current {\it Swift} sample on delay time distribution models. We find that log-normal models with mean delay times of $\approx 4-6$~Gyr are consistent with the observed distribution, but can be ruled out to $95\%$ confidence with an additional $\approx1-5$~{\it Swift} SGRBs recovered at $z>1.5$. In contrast, power-law models with $\propto$ $t^{-1}$ are consistent with the redshift distribution and can accommodate up to $\approx30$ SGRBs at these redshifts. Under this model, we predict that $\approx 1/3$ of the current {\it Swift} population of SGRBs is at $z>1$. The future discovery or recovery of existing high-$z$ SGRBs will provide significant discriminating power on their delay time distributions, and thus their formation channels.
