On the Anticorrelation between Duration and Redshift in Gamma-Ray Bursts
On the Anticorrelation between Duration and Redshift in Gamma-Ray Bursts
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DOI：
10.3847/1538-4357/acc795
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发表时间：
2022-12
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影响因子：
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通讯作者：
N. Lloyd-Ronning;Jarrett L. Johnson;R. Cheng;Ken Luu;P. Sanderbeck;Lailani Kenoly;C. Toral
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作者：
N. Lloyd-Ronning;Jarrett L. Johnson;R. Cheng;Ken Luu;P. Sanderbeck;Lailani Kenoly;C. Toral
对于持续时间超过两秒的伽马射线暴（所谓的长伽马射线暴），平均而言，对于红移较低的伽马射线暴，内在瞬发伽马射线发射的持续时间似乎更长。我们探索这个持续时间的本质——红移反相关，描述这种宇宙演化可能出现的系统和条件。特别是，我们探索了它对大质量恒星前身金属丰度的依赖，因为我们可以可靠地依赖平均恒星金属丰度随着红移的减小而增加。尽管金属丰度较高/红移较低的恒星会通过线驱动风损失质量和角动量，但在某些情况下，这些恒星在塌陷时能够形成更延伸的吸积盘，从而可能导致持续时间更长的伽玛暴。我们还研究了这种持续时间-红移趋势如何在由大质量恒星和致密伴星组成的相互作用的双星模型中出现，最近被认为是射电明亮的伽玛暴的前身。在某些条件下，具有较高金属丰度和较低红移的大质量恒星的质量损失和状态方程效应会减少双星分离。这会导致大质量恒星自转，并在大质量恒星坍塌时产生持续时间更长的伽玛暴。最后，持续时间-红移趋势也可能得到相对较多的低红移原位诞生的小分离双星的支持。
For gamma-ray bursts (GRBs) with durations greater than two seconds (so-called long GRBs), the intrinsic prompt gamma-ray emission appears, on average, to last longer for bursts at lower redshifts. We explore the nature of this duration–redshift anticorrelation, describing systems and conditions in which this cosmological evolution could arise. In particular, we explore its dependence on the metallicity of a massive star progenitor, because we can securely count on the average stellar metallicity to increase with decreasing redshift. Although stars with higher metallicity/lower redshift lose mass and angular momentum through line-driven winds, in some cases these stars are able to form more extended accretion disks when they collapse, potentially leading to longer-duration GRBs. We also examine how this duration–redshift trend may show up in interacting binary models composed of a massive star and compact object companion, recently suggested to be the progenitors of radio-bright GRBs. Under certain conditions, mass loss and equation-of-state effects from massive stars with higher metallicity and lower redshift can decrease the binary separation. This can then lead to spin-up of the massive star and allow for a longer-duration GRB upon the massive star’s collapse. Finally, the duration–redshift trend may also be supported by a relatively larger population of small-separation binaries born in situ at low redshift.