The distribution of delay times between the formation of binary black hole (BBH) progenitors and their gravitational-wave (GW) merger provides important clues about their unknown formation histories. When inferring the delay time distribution, it is typically assumed that BBH progenitor formation traces the star formation rate (SFR). In this work, we consider the rate of long gamma-ray bursts (LGRBs) instead of the SFR. LGRBs are thought to correspond to the formation of (possibly spinning) black holes, and may therefore be related to the BBH progenitor population. By comparing the redshift evolution of the LGRB rate as inferred by G. Ghirlanda & R. Salvaterra and the BBH merger rate inferred by LIGO-Virgo-KAGRA observations, we find that the delay time distribution between LGRBs and BBH mergers is well described by a power law with minimum delay time 10 Myr and slope (90% credibility). This matches theoretical expectations for the BBH delay time distribution, which in turn lends support to the hypothesis that LGRBs trace BBH progenitor formation. However, comparing the absolute rates of these two populations, we find that at most of LGRBs may evolve into merging BBHs. We also consider the possibility that LGRBs only produce BBH systems with large aligned spins (with effective inspiral spin χeff > 0.2). In this case, we find and the delay time distribution favors the steepest power-law slopes we consider (α = −2). We argue that asynchronous observations of LGRBs and GWs provide a powerful multimessenger probe of black hole life cycles across cosmic history.

中文翻译：

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长伽马射线暴是合并双黑洞的祖先吗？


双黑洞 （BBH） 祖先的形成与其引力波 （GW） 合并之间的延迟时间分布为它们未知的形成历史提供了重要线索。在推断延迟时间分布时，通常假设 BBH 祖先形成跟踪恒星形成速率 （SFR）。在这项工作中，我们考虑了长伽马射线暴 （LGRBs） 的速率，而不是 SFR。LGRB 被认为对应于（可能是旋转的）黑洞的形成，因此可能与 BBH 祖细胞群有关。通过比较G. Ghirlanda和R. Salvaterra推断的LGRB速率的红移演变和LIGO-Virgo-KAGRA观测推断的BBH合并速率，我们发现LGRBs和BBH合并之间的延迟时间分布可以用最小延迟时间10 Myr和斜率（90%可信度）的幂律很好地描述。这与对 BBH 延迟时间分布的理论预期相符，这反过来又支持 LGRB 追踪 BBH 祖细胞形成的假设。然而，比较这两个群体的绝对比率，我们发现大多数 LGRB 可能会演变成合并的 BBH。我们还考虑了 LGRBs 仅产生具有大对齐自旋的 BBH 系统的可能性（具有有效的螺旋自旋 χeff > 0.2）。在这种情况下，我们发现延迟时间分布有利于我们考虑的最陡幂律斜率 （α = −2）。我们认为，对 LGRBs 和 GWs 的异步观测为宇宙历史上的黑洞生命周期提供了一个强大的多信使探针。