标题： 双中子星合并相对于其宿主星系的偏移 II. 短时伽马射线暴 显示英文标题

标题： Binary neutron star merger offsets from their host galaxies II. Short-duration gamma-ray bursts

摘要： 双中子星（BNSs）和中子星-黑洞（NSBHs）双星的合并长期以来被认为与短时伽马射线暴（SGRBs）有关。然而，尽管它们的恒星前身星，SGRBs通常出现在宿主星系的恒星光之外。这通常归因于超新星踢动，将SGRB的前身星从原始恒星群体中移开。我们的目标是使用恒星种群合成模型来重现和解释基于观测宿主特性的真实星系模型中统计样本SGRB的观测偏移量。我们逐个案例地从观测特性中推导出宿主星系势场，并使用三种不同的踢动方案，通过BPASS代码模拟合成BNSs和NSBHs的星系轨迹。我们比较预测和观测的偏移量，以研究速度踢动、宿主星系类型和宿主关联标准的影响。结果证实，SGRB群体的位置与被踢动的BNS或BHNS前身星的预期一致，这意味着这样的合并是主要（如果不是唯一）的前身系统。与BNSs相比，NSBHs的预测拟合显著较差，而在比较不同的踢动方案时，我们发现没有显著差异。对于晚型宿主，当我们包括具有高达20%偶然对齐概率Pch的宿主时，得到最好的一致性，而较低的Pch阈值会导致我们高估SGRB偏移量。我们认为Pch在最大偏移量处对可行宿主存在偏差，并建议对晚型宿主使用不太保守的Pch阈值。对于早型宿主，无论应用何种Pch阈值，预测在某些情况下都会低估SGRB偏移量。我们认为这可能是由于模型缺少星系演化或虚假的宿主关联。 显示英文摘要

摘要： The mergers of binary neutron stars (BNSs) and neutron star-black holes (NSBHs) binaries have long been linked to short-duration gamma-ray bursts (SGRBs). However, despite their stellar progenitors, SGRBs are often found outside the stellar light of the host galaxy. This is commonly attributed to supernova kicks, which displace the SGRB progenitors from the original stellar population. Our goal is to use stellar population synthesis models to reproduce and interpret the observed offsets of a statistical sample of SGRBs, using realistic galactic models based on the observed host properties. We derive the host galaxy potentials from the observed properties on a case-by-case basis, and simulate the galactic trajectories of synthetic BNSs and NSBHs from the BPASS code using three different kick prescriptions. We compare predicted and observed offsets to investigate the impact of velocity kicks, host galaxy types, and host association criteria. The results confirm that the locations of the SGRB population are consistent with the expectations of kicked BNS or BHNS progenitors, implying that such mergers are the dominant (if not only) progenitor system. Predictions for NSBHs provide a significantly worse fit compared to BNSs, while we find no significant difference when comparing different kick prescriptions. For late-type hosts, we find the best agreement when including hosts with a probability of chance alignment Pch up to 20%, while lower Pch thresholds lead us to overestimate SGRB offsets. We argue that Pch is biased against viable hosts at the largest offsets, and suggest the use of less conservative Pch thresholds for late-type hosts. For early-type hosts, the predictions underestimate SGRB offsets in a few cases regardless of the Pch threshold applied. We argue that this is likely due to the models missing galaxy evolution, or spurious host associations.