Short GRB Host Galaxies. II. A Legacy Sample of Redshifts, Stellar Population Properties, and Implications for Their Neutron Star Merger Origins
Short GRB Host Galaxies. II. A Legacy Sample of Redshifts, Stellar Population Properties, and Implications for Their Neutron Star Merger Origins
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DOI：
10.3847/1538-4357/ac91d1
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发表时间：
2022-06
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通讯作者：
A. Nugent;W. Fong;Y. Dong 董;J. Leja;E. Berger;M. Zevin;R. Chornock;B. Cobb;L. Kelley;C. Kilpatrick;A. Levan;R. Margutti;K. Paterson;D. Perley;A. R. Escorial;N. Smith;N. Tanvir
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作者：
A. Nugent;W. Fong;Y. Dong 董;J. Leja;E. Berger;M. Zevin;R. Chornock;B. Cobb;L. Kelley;C. Kilpatrick;A. Levan;R. Margutti;K. Paterson;D. Perley;A. R. Escorial;N. Smith;N. Tanvir
我们提出了69个短伽玛射线暴（GRB）的宿主星系，代表最大的统一建模的样本，到目前为止的恒星的人口特性。使用勘探恒星人口推断代码，我们共同适合每个宿主星系的光度和/或光谱。我们发现了一个总体的中位红移z=0.64−0.32+0.83（68%的置信度），包括9个在z = 1处的光度红移。我们进一步发现，质量加权年龄的中位数t m = 0.8−0.53+2.71 Gyr，恒星质量log（M */M）= 9.69−0.65+0.75，星星形成速率SFR = 1.44−1.35+9.37 M yr−1，恒星金属丰度log（Z */Z）= −0.38−0.42+0.44，AV的灰尘衰减=0.43 - 0.36+0.85 mag（68%置信度）。总的来说，大多数短伽玛暴宿主都是恒星形成的（约84%），有一小部分是过渡的（约6%）或静止的（约10%）;然而，我们观察到一个更大的比例（约40%）的静止和过渡的宿主在z = 0.25，与星系演化相称。我们发现，短伽玛射线暴主机填充恒星形成的正常场星系的主要序列，但不包括尽可能多的高质量星系的一般星系人口，这意味着他们的二进制中子星星（BNS）合并的祖先是依赖于主机星星形成和恒星质量的组合。年龄和红移的分布意味着一个宽的延迟时间分布，在z > 1处有一个快速合并通道，中子星星双星的形成效率从高红移到低红移逐渐降低。如果短GRB主机是目前引力波探测器视界内BNS合并主机的代表，这些结果可以为未来的电磁同行搜索提供信息。所有的数据和建模产品都可以在研究伽马射线暴宿主特征的宽带知识库网站上找到。
We present the stellar population properties of 69 short gamma-ray burst (GRB) host galaxies, representing the largest uniformly modeled sample to date. Using the Prospector stellar population inference code, we jointly fit photometry and/or spectroscopy of each host galaxy. We find a population median redshift of z=0.64−0.32+0.83 (68% confidence), including nine photometric redshifts at z ≳ 1. We further find a median mass-weighted age of t m = 0.8−0.53+2.71 Gyr, stellar mass of log(M */M ⊙) = 9.69−0.65+0.75 , star formation rate of SFR = 1.44−1.35+9.37 M ⊙ yr−1, stellar metallicity of log(Z */Z ⊙) = −0.38−0.42+0.44 , and dust attenuation of AV=0.43−0.36+0.85 mag (68% confidence). Overall, the majority of short GRB hosts are star-forming (≈84%), with small fractions that are either transitioning (≈6%) or quiescent (≈10%); however, we observe a much larger fraction (≈40%) of quiescent and transitioning hosts at z ≲ 0.25, commensurate with galaxy evolution. We find that short GRB hosts populate the star-forming main sequence of normal field galaxies, but do not include as many high-mass galaxies as the general galaxy population, implying that their binary neutron star (BNS) merger progenitors are dependent on a combination of host star formation and stellar mass. The distribution of ages and redshifts implies a broad delay-time distribution, with a fast-merging channel at z > 1 and a decreased neutron star binary formation efficiency from high to low redshifts. If short GRB hosts are representative of BNS merger hosts within the horizon of current gravitational wave detectors, these results can inform future searches for electromagnetic counterparts. All of the data and modeling products are available on the Broadband Repository for Investigating Gamma-ray burst Host Traits website.