论文标题
在迅速时代，在低红移处解决了长长的GRB
Resolving the Excess of Long GRBs at low redshift in the Swift Era
论文作者
论文摘要
Utilizing more than 100 long gamma-ray bursts (LGRBs) in the Swift-Ryan-2012 sample that include the observed redshifts and jet angles, Le & Mehta performed a timely study of the rate-density of LGRBs with an assumed broken power law GRB spectrum and obtained a GRB-burst-rate functional form that gives acceptable fits to the preSwift and Swift redshift and jet angle distributions.结果表明，在Swift样本中，红移低于$ z \ sim 2 $的LGRB过量。在这项工作中，我们正在调查过量是否是由宇宙哈勃恒定$ h_0 $，$γ$ - ray能量释放的$e_γ$，低和高能指数（$α，β，β$）的频带功能，最小和最大jet angles $θ_{在Swift-ryan-2012样本中偏见。我们的分析表明，上述物理参数均未解决多余的问题，而是表明Swift-ryan-2012〜样品会偏向可能的余辉选择效果。以下模型物理参数值为Swift-ryan-2012和Preswift〜样品提供了最佳拟合：Hubble常数$ H_0 = 72 = 72 \，{\ rm km s s^{ - 1} mpc^{ - 1}} $ $β\sim -2.13$, the jet angles of $θ_{\rm j,max} \sim 0.8$ rad, and $θ_{\rm j, min} \sim 0.065$ and $\sim 0.04$ rad for preSwift and Swift, respectively, $s \sim -1.55$ the jet angle power-law index, and a GRB formation rate that is similar to the霍普金斯和比科姆观察了星形的历史，并由李扩展。但是，使用Swift Gamma爆发主机Galaxy Legacy调查（Shoals）Swift-Perley LGRB样本并应用与上述相同的物理参数值，但是，我们的模型在此数据集中提供了一致的结果，并且在任何红移时都没有过多的LGRB。
Utilizing more than 100 long gamma-ray bursts (LGRBs) in the Swift-Ryan-2012 sample that include the observed redshifts and jet angles, Le & Mehta performed a timely study of the rate-density of LGRBs with an assumed broken power law GRB spectrum and obtained a GRB-burst-rate functional form that gives acceptable fits to the preSwift and Swift redshift and jet angle distributions. The results indicated an excess of LGRBs at redshift below $z \sim 2$ in the Swift sample. In this work, we are investigating if the excess is caused by the cosmological Hubble constant $H_0$, the $γ$-ray energy released $E_γ$, the low- and high-energy indices ($α, β$) of the Band function, the minimum and maximum jet angles $θ_{\rm j,min}$ and $θ_{\rm j, max}$, or that the excess is due to a biased in the Swift-Ryan-2012 sample. Our analyses indicate that none of the above physical parameters resolved the excess problem, but suggesting that the Swift-Ryan-2012~sample is biased with possible afterglow selection effect. The following model physical parameter values provide the best fit to the Swift-Ryan-2012 and preSwift~samples: the Hubble constant $H_0 = 72 \, {\rm km s^{-1} Mpc^{-1}}$, the energy released $E_γ\sim 4.47 \times 10^{51}$ erg, the energy indices $α\sim 0.9$ and $β\sim -2.13$, the jet angles of $θ_{\rm j,max} \sim 0.8$ rad, and $θ_{\rm j, min} \sim 0.065$ and $\sim 0.04$ rad for preSwift and Swift, respectively, $s \sim -1.55$ the jet angle power-law index, and a GRB formation rate that is similar to the Hopkins & Beacom observed star formation history and as extended by Li. Using the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (SHOALS) Swift-Perley LGRB sample and applying the same physical parameter values as above, however, our model provides consistent results with this data set and indicating no excess of LGRBs at any redshift.
