宇宙学模拟中长伽马射线暴宿主星系的性质
Properties of Long Gamma-Ray Burst Host Galaxies in Cosmological Simulation
摘要：
利用高分辨率N体模拟和半解析星系形成模型相结合的星系星表研究了长伽马射线暴（LGRB）宿主星系的性质。我们假设LGRB起源于大质量年轻恒星的死亡，并分析了不同的金属丰度限制对祖星的影响。正如预期的那样，没有对祖星金属丰度限制的宿主样品提供了宇宙恒星形成历史的完美示踪剂。当LGRB需要由低金属量恒星产生时，它们在较低的红移处追踪宇宙恒星形成率的下降部分，这是金属量全球增加的结果。我们研究了高红移（~9）的宿主星系的性质，发现它们通常具有低金属丰度（Z<0.5 Z_sun），并且它们比平均星系群小（M<10^9 M_sun），更蓝，更年轻，与观测数据一致。它们也比宇宙中典型的L_* 星系更少聚集，它们的后代是巨大的，红色的，居住在星系群中，晕质量在10^{13} M_sun到10^{14} M_sun之间。
英文摘要：
We use galaxy catalogues constructed by combining high-resolution N-body simulations with semi-analytic models of galaxy formation to study the properties of Long Gamma-Ray Burst (LGRB) host galaxies. We assume that LGRBs originate from the death of massive young stars and analyse how results are affected by different metallicity constraints on the progenitor stars. As expected, the host sample with no metallicity restriction on the progenitor stars provides a perfect tracer of the cosmic star formation history. When LGRBs are required to be generated by low-metallicity stars, they trace a decreasing fraction of the cosmic star formation rate at lower redshift, as a consequence of the global increase in metallicity. We study the properties of host galaxies up to high redshift (~9), finding that they typically have low-metallicity (Z<0.5 Z_sun) and that they are small (M<10^9 M_sun), bluer and younger than the average galaxy population, in agreement with observational data. They are also less clustered than typical L_* galaxies in the Universe, and their descendents are massive, red and reside in groups of galaxies with halo mass between 10^{13} M_sun to 10^{14} M_sun.
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