论文标题
限制长伽马射线爆发的内在种群：对光谱相关性，宇宙进化的影响及其用作恒星形成的示踪剂
Constraining the intrinsic population of Long Gamma-Ray Bursts: implications for spectral correlations, cosmic evolution and their use as tracers of star formation
论文作者
论文摘要
长长的伽马射线爆发（LGRB）已被证明是宇宙的强大探针，特别是为了研究恒星形成速率至非常高的红移（$ z \ sim 9 $）。由于LGRB仅由一小部分巨星产生，因此对它们的基本固有种群有充分的了解是为了将它们用作宇宙学探针而不引入任何不必要的偏见，这一点至关重要。这项工作的目的是限制和表征这种内在人群。我们开发了一个蒙特卡洛模型，其中每个爆发都由其红移及其在灯峰峰值处的性质描述。我们通过将我们的合成种群与基于CGRO/BATSE，FERMI/GBM和具有适当通量阈值的Swift/BAT样品进行比较，得出了最佳拟合参数。我们探讨了不同方案的光度函数和/或红移分布的宇宙演化，以及包括固有光谱 - 能源（EP-L）相关性的存在。我们发现，固有的EP-L相关的存在是优选的，但具有比观察到的（$α_A\ sim 0.3 $）和更大的散布（$ \ sim 0.4 $ dex）的浅坡度。我们发现亮度的宇宙演化与LGRB速率之间存在很强的变性，并表明需要比浅滩更大，更深的样本要增加三倍以提高这种脱位。我们观察到的结论是，EP-L相关性不能仅通过选择效应来解释，尽管这些相关性确实在塑造观察到的关系中起作用。光度函数的宇宙演变与LGRB的红移分布之间的退化应包括在恒星形成率估计的不确定性中； $ z = 6 $的10倍为10倍，在$ z = 9 $时达到50倍。
Long Gamma-Ray Bursts (LGRBs) have been shown to be powerful probes of the Universe, in particular to study the star formation rate up to very high redshift ($z \sim 9$). Since LGRBs are produced by only a small fraction of massive stars, it is paramount to have a good understanding of their underlying intrinsic population in order to use them as cosmological probes without introducing any unwanted bias. The goal of this work is to constrain and characterise this intrinsic population. We developed a Monte Carlo model where each burst is described by its redshift and its properties at the peak of the lightcurve. We derived the best fit parameters by comparing our synthetic populations to carefully selected observational constraints based on the CGRO/BATSE, Fermi/GBM and Swift/BAT samples with appropriate flux thresholds. We explored different scenarios in terms of cosmic evolution of the luminosity function and/or of the redshift distribution as well as including or not the presence of intrinsic spectral-energetics (Ep-L) correlations. We find that the existence of an intrinsic Ep-L correlation is preferred but with a shallower slope than observed($α_A \sim 0.3$) and a larger scatter ($\sim 0.4$ dex). We find a strong degeneracy between the cosmic evolution of the luminosity and of the LGRB rate, and show that a sample both larger and deeper than SHOALS by a factor of three is needed to lift this degeneracy. The observed We conclude that Ep-L correlation cannot be explained only by selection effects although these do play a role in shaping the observed relation. The degeneracy between cosmic evolution of the luminosity function and of the redshift distribution of LGRBs should be included in the uncertainties of star formation rate estimates; these amount to a factor of 10 at $z=6$ and up to a factor of 50 at $z=9$.
