Title: The Afterglows of Swift-era Gamma-Ray Bursts. I. Comparing pre-Swift and Swift era Long/Soft (Type II) GRB Optical Afterglows Show Chinese title

Title: Swift时代伽玛射线暴的余辉。 I. 比较Swift时代前和Swift时代长/软（II型）伽玛射线暴的光学余辉

Abstract: We have gathered optical photometry data on a large sample of Swift-era gamma-ray burst (GRB) afterglows. We analyzed their light curves and derive spectral energy distributions for the sample with the best data quality, allowing us to derive the host galaxy extinction. We transform the afterglow light curves into an extinction-corrected $z=1$ system and compare their luminosities with a sample of pre-Swift afterglows. We find that the luminosity distribution of the two afterglow samples are very similar, and that a fainter sample can be explained by a moderate amount of line-of-sight host extinction. We derive bolometric isotropic energies for all GRBs in our sample, and find only a tentative correlation between the prompt energy release and the optical afterglow luminosity. Furthermore, we propose the existence of an upper ceiling on afterglow luminosities and study the luminosity distribution at early times, which was not accessible before the advent of the Swift satellite. Finally, we postulate the existence of an intermediate class of long GRBs which lie between the typical high-luminosity, high-redshift events described in the rest of the paper and nearby low-luminosity events associated with spectroscopic SNe in terms of energetics and redshift distribution. Show Chinese abstract

Abstract: 我们收集了大量Swift时代伽马射线暴（GRB）余辉的光学测光数据。 我们分析了它们的光变曲线，并对数据质量最好的样本推导出光谱能量分布，使我们能够推导出宿主星系消光。 我们将余辉光变曲线转换为消光校正的$z=1$系统，并将其光度与一组Swift之前的余辉样本进行比较。 我们发现两个余辉样本的光度分布非常相似，较暗的样本可以通过适度的视线方向宿主消光来解释。 我们推导了我们样本中所有GRB的全波段各向同性能量，并发现脉冲能量释放和光学余辉光度之间仅存在一个初步的相关性。 此外，我们提出余辉光度存在一个上限，并研究了早期时间的光度分布，这在Swift卫星出现之前是无法访问的。 最后，我们假设存在一个中间类的长时标GRB，它们在能量和红移分布方面介于本文其余部分描述的典型高光度、高红移事件和与光谱超新星相关的附近低光度事件之间。