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arXiv 2209.02175astro-ph.HEastro-ph.GA
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长伽马射线暴宿主星系的恒星质量函数

The Stellar-mass Function of Long Gamma-Ray Burst Host Galaxies

Guang-Xuan Lan, Jun-Jie Wei, Ye Li, Hou-Dun Zeng, Xue-Feng Wu

摘要:

长伽马射线暴(GRB)作为探测宇宙恒星形成率(SFR)的一种潜在工具已经被讨论了很长时间。一些研究发现,在高红移时,相对于银河系推断的SFR,GRB的速率有所增强,这表明GRB可能不是恒星形成的良好示踪剂。然而,在这些研究中,在任何红移测量的伽玛暴速率是该时期所有星系的平均值。要深入了解伽玛暴产生与环境之间的联系,还需要直接描述伽玛暴宿主星系的数量。基于一个完整的样本的伽玛暴主机,我们约束的恒星质量函数(SMF)的伽玛暴主机人口的红移演化研究。我们的研究结果证实,一个强大的红移演化的能量(与$δ=2.47^{+0.73}_{-0.89}$的演化指数)或密度($δ=1.82^{+0.22}_{-0.59}$)是需要的,以占的意见。GRB宿主SMF可以用Schechter函数很好地描述,该函数具有幂律指数$ξ\approx-1.10$和转折质量$M_{b,0}\approx4.9\times10^{10}$ ${\rm M}_\odot$,与假设的演化效应无关。这是GRB宿主SMF的第一个配方。观测到的GRB速率和星系推断的SFR之间的差异也可以用一个不断发展的SMF来解释。

英文摘要:

Long gamma-ray bursts (GRBs) have been discussed as a potential tool to probe the cosmic star formation rate (SFR) for a long time. Some studies found an enhancement in the GRB rate relative to the galaxy-inferred SFR at high redshifts, which indicates that GRBs may not be good tracers of star formation. However, in these studies, the GRB rate measured at any redshift is an average over all galaxies at that epoch. A deep understanding of the connection between GRB production and environment also needs to characterize the population of GRB host galaxies directly. Based on a complete sample of GRB hosts, we constrain the stellar-mass function (SMF) of GRB hosts, and examine redshift evolution in the GRB host population. Our results confirm that a strong redshift evolution in energy (with an evolution index of $δ=2.47^{+0.73}_{-0.89}$) or in density ($δ=1.82^{+0.22}_{-0.59}$) is needed in order to account for the observations. The GRB host SMF can be well described by the Schechter function with a power-law index $ξ\approx-1.10$ and a break mass $M_{b,0}\approx4.9\times10^{10}$ ${\rm M}_\odot$, independent of the assumed evolutionary effects. This is the first formulation of the GRB host SMF. The observed discrepancy between the GRB rate and the galaxy-inferred SFR may also be explained by an evolving SMF.

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