AI 中文总结
本文通过分析Swift卫星探测的GRB样本，发现近邻宇宙中部分长GRB可能起源于致密天体并合，其发生率与短GRB相近，对伽马射线暴前身天体的传统二分关系提出了修正。
AI 中文摘要
近期，数例与千新星相关的长伽马射线暴（GRB）对伽马射线暴持续时间与前身天体系统之间传统的二分对应关系提出了质疑。本文利用可约束前身天体的GRB样本，研究了看似跨越该二分界限的暴的发生率与特性。我们首先构建了一个z<0.3范围内Swift卫星探测到的已知GRB样本，共得到8个短GRB和21个长GRB；在这些长GRB中，我们发现9个暴具有超新星辐射的深限、千新星辐射的证据，或与宁静星系成协，占z<0.3范围内所有GRB的31%±9%，这意味着近邻宇宙中相当一部分长GRB可能并非起源于大质量恒星。在z<0.3范围内，未观测到任何短GRB有对应的超新星。将范围扩展至z<0.5及其他伽马射线望远镜时，我们得到的数量相当，但能可靠约束前身天体的暴占比有所降低。我们进一步发现，无成协超新星的长GRB平均余辉更暗，且位于恒星形成活动较弱的宿主星系中，这支持这类事件可能起源于致密天体并合的观点。我们估算了近似的体发生率，发现短GRB与无超新星长GRB的（共线）发生率相近，约为0.5-2.5 Gpc⁻³ yr⁻¹，不过对完整Swift目录的低红移宿主搜寻表明，我们的样本可能约50%完整。若无超新星长GRB起源于致密天体并合，这意味着z<0.3范围内约30%-70%的Swift长GRB可能起源于并合，且z<0.3时长、短GRB对应的并合发生率相当，这些发现对引力波符合事件与重元素富集具有重要意义。
英文摘要
Recently, several long-duration gamma-ray bursts (GRBs) associated with kilonovae have cast doubt on the traditional, dichotomous mapping between gamma-ray duration and progenitor system. Here, we investigate the rates and properties of bursts which appear to cross this dichotomy using a sample of GRBs for which progenitor constraints are possible. We first build a sample of known Swift-detected GRBs at z<0.3, finding 8 short- and 21 long-duration GRBs. Of these long GRBs, we find 9 bursts with deep limits on supernova emission, evidence for kilonova emission, or association with a quiescent galaxy (31% $\pm$ 9% of all GRBs at z<0.3), implying that a significant fraction of nearby long GRBs likely do not come from massive stars. At z<0.3, no short GRB has an observed supernova counterpart. We find comparable numbers when expanding to z<0.5 and other gamma-ray telescopes, though we obtain a decreased fraction of bursts with robust constraints on a progenitor. We further find that the long GRBs with no associated supernovae possess on-average fainter afterglows and lie in less star-forming host galaxies than those with supernovae, supporting that these events may originate in compact object mergers. We estimate approximate volumetric rates, finding similar (on-axis) rates for short GRBs and supernova-less long GRBs of $\sim 0.5-2.5$ Gpc$^{-3}$ yr$^{-1}$, although a search for possible low-redshift hosts of the complete Swift catalog suggests that our sample may be $\sim$50% complete. If supernova-less long GRBs arise from compact object mergers, this implies that $\sim$ 30-70% of all z<0.3 Swift long GRBs may arise from mergers and that the $z<0.3$ rates of mergers from long and short GRBs are comparable. These findings hold substantial implications for gravitational-wave coincidence and heavy element enrichment.
CommentsSubmitted to MNRAS. 28 pages, 13 figures, 6 tables
