一种量化伽马射线暴“偏差”的方法。在红移0-1.1范围内的应用
A method for quantifying the Gamma Ray Burst "bias". Application in the redshift range 0-1.1
摘要：
长伽马射线暴（LGRB）与大质量恒星演化的最后阶段有关。因此，它们应该遵循星系的恒星形成率（SFR）。我们可以用它们来探测遥远宇宙中的恒星形成星系（SFG）。在一个给定的星系中，LGRB的发生率和它的SFR之间的关系（我们称之为LGRB的“偏差”）可能是复杂的，因为我们有迹象表明LGRB的宿主并不是SFG的一般种群的完美类似物。在这项工作中，我们试图量化的LGRB的偏差对它们的宿主星系的物理参数，如SFR或恒星质量的依赖。我们提出了一个经验的方法的基础上比较恒星质量函数（和SFR分布）的LGRB主机和SFG，以找到如何的偏差取决于恒星质量或SFR。通过将这种方法应用于红移低于1.1的LGRB宿主星系的样本，其中SFG的性质得到了很好的建立，并且LGRB宿主星系的性质可以从观测中推导出来（对于恒星质量大于10**9.25 Msun和SFR大于1.8 Msun / yr），我们发现LGRB偏差取决于恒星质量和SFR。我们发现，偏见减少与SFR，即我们看到没有偏好高SFG，一旦考虑到大量的大质量恒星的星系中具有较大的SFR。我们没有发现比恒星形成率（SSFR）的任何趋势，但在我们的研究SSFR的动力学范围是狭窄的。虽然通过间接的方法，我们将这些趋势与金属丰度的LGRB率/ SFR比的可能降低联系起来。我们提出的方法表明的趋势，可能是有用的约束模型的LGRB祖细胞，表现出明显的减少LGRB的偏见与金属丰度。这是有希望的未来作为研究的LGRB主机的数量将增加。
英文摘要：
Long Gamma Ray Bursts (LGRBs) are related to the final stages of evolution of massive stars. As such, they should follow the star formation rate (SFR) of galaxies. We can use them to probe for star-forming galaxies (SFGs) in the distant universe following this assumption. The relation between the rate of LGRBs in a given galaxy and its SFR (that we call the LGRB "bias") may be complex, as we have indications that the LGRB hosts are not perfect analogues to the general population of SFGs. In this work, we try to quantify the dependence of the LGRB bias on physical parameters of their host galaxy such as the SFR or the stellar mass. We propose an empirical method based on the comparison of stellar mass functions (and SFR distributions) of LGRB hosts and of SFGs in order to find how the bias depends on the stellar mass or the SFR. By applying this method to a sample of LGRB hosts at redshifts lower than 1.1, where the properties of SFGs are well established, and where the properties of LGRB host galaxies can be deduced from observations (for stellar masses larger than 10**9.25 Msun and SFR larger than 1.8 Msun / yr), we find that the LGRB bias depends on both the stellar mass and SFR. We find that the bias decreases with the SFR, i.e. we see no preference for highly SFGs, once taken into account the larger number of massive stars in galaxies with larger SFR. We do not find any trend with the specific star formation rate (SSFR) but the dynamical range in SSFR in our study is narrow. Although through an indirect method, we relate these trends to a possible decrease of the LGRBs rate / SFR ratio with the metallicity. The method we propose suggests trends that may be useful to constrain models of LGRB progenitors, showing a clear decrease of the LGRB bias with the metallicity. This is promising for the future as the number of LGRB hosts studied will increase.
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