论文标题
阿尔玛（Alma）对长持续伽马射线爆发的宿主星系的观察。 I：分子气体缩放关系
ALMA CO Observations of the Host Galaxies of Long-duration Gamma-ray Bursts. I: Molecular Gas Scaling Relations
论文作者
论文摘要
我们通过使用Atacama大毫米/毫米阵列，在z = 0.1-2.5时介绍了14个长期伽马射线爆发（GRB）的托管观测结果的结果。我们成功地检测了八个宿主（z = 0.3-2）中的CO（3-2）或CO（4-3）发射，这使GRB宿主的样本量增加了一倍以上。派生的分子气体质量为$ m _ {\ rm as GAS} =（0.2-6）\ times 10^{10} $ $ m _ {\ odot} $，假设金属依赖性co-to-h $ _2 $转换因子。通过使用具有分子气体估计值的最大的GRB宿主样品（总共25个，其中14个是共同检测的），包括文献的结果，我们将分子气体特性与其他恒星形成星系（SFG）的特性进行了比较。与其他SFG相比，GRB宿主往往具有较高的分子气体质量分数（$μ_{\ rm GAS} $）和较短的气体耗尽时间表（$ t _ {\ rm depl} $），与其他SFG相比，尤其是在类似的红色SFG上，尤其是在$ z \ slyssim 1 $中。这可能是GRB主机的共同属性，也可能是通常在主要序列线上的目标所引入的效果。为了消除选择偏差的效果，我们分析了$μ_ {\ rm Gas} $和$ t _ {\ rm DEPL} $，这是距主序列线（$δ$ MS）的距离的函数。我们发现，GRB主机遵循与其他SFG相同的缩放关系，其中$μ_ {\ rm Gas} $增加，$ t _ {\ rm DEPL} $随着$δ{\ rm MS} $的增加而减小。与其他类似SFR和恒星质量的SFG相比，没有观察到分子气体缺陷。这些发现表明，在GRB宿主中预计与其他SFG相同的星形形成机制将发生。
We present the results of CO observations toward 14 host galaxies of long-duration gamma-ray bursts (GRBs) at z = 0.1-2.5 by using the Atacama Large Millimeter/submillimeter Array. We successfully detected CO(3-2) or CO(4-3) emission in eight hosts (z = 0.3-2), which more than doubles the sample size of GRB hosts with CO detection. The derived molecular gas mass is $M_{\rm gas} = (0.2-6) \times 10^{10}$ $M_{\odot}$ assuming metallicity-dependent CO-to-H$_2$ conversion factors. By using the largest sample of GRB hosts with molecular gas estimates (25 in total, of which 14 are CO-detected) including results from the literature, we compared molecular gas properties with those of other star-forming galaxies (SFGs). The GRB hosts tend to have a higher molecular gas mass fraction ($μ_{\rm gas}$) and a shorter gas depletion timescale ($t_{\rm depl}$) as compared with other SFGs at similar redshifts especially at $z \lesssim 1$. This could be a common property of GRB hosts or an effect introduced by the selection of targets which are typically above the main-sequence line. To eliminate the effect of selection bias, we analyzed $μ_{\rm gas}$ and $t_{\rm depl}$ as a function of the distance from the main-sequence line ($δ$MS). We find that the GRB hosts follow the same scaling relations as other SFGs, where $μ_{\rm gas}$ increases and $t_{\rm depl}$ decreases with increasing $δ{\rm MS}$. No molecular gas deficit is observed when compared to other SFGs of similar SFR and stellar mass. These findings suggest that the same star-formation mechanism is expected to be happening in GRB hosts as in other SFGs.
