在宇宙$γ$射线背景中评价恒星形成星系留下的特征
Assessing the signatures imprinted by star-forming galaxies in the cosmic $γ$-ray background
摘要：
近年来，在本宇宙中的恒星形成星系（SFG）中，包括M82、NGC 253、Arp 220和M33，都探测到了$γ$射线辐射。这种辐射的大部分被认为是强子起源，来自宇宙射线（CR）与其宿主星系的星际介质的相互作用。遥远的SFG在$γ$射线中也可能是明亮的。虽然它们作为点源是不可分辨的，但遥远的未分辨SFG群对河外$γ$射线背景（EGB）贡献了$γ$射线。尽管\textit{Fermi} -LAT $γ$射线空间望远镜在十多年的运行中收集了大量高质量的全天空EGB数据，但SFG对EGB的确切贡献仍然没有得到解决。在这项研究中，我们模拟的$γ$ -射线发射SFG人口，并表明，这种发射的特点是只有少数的物理动机的参数。我们进一步表明，源人口将在EGB中留下各向异性的签名，这可以用来产生有关的基本属性，动力学和富CR的SFG的演化信息。
英文摘要：
In recent years, $γ$-ray emission has been detected from star-forming galaxies (SFGs) in the local universe, including M82, NGC 253, Arp 220 and M33. The bulk of this emission is thought to be of hadronic origin, arising from the interactions of cosmic rays (CRs) with the interstellar medium of their host galaxy. Distant SFGs are presumably also bright in $γ$-rays. Although they would not be resolvable as point sources, distant unresolved SFG populations contribute $γ$-rays to the extra-galactic $γ$-ray background (EGB). Despite the wealth of high-quality all-sky EGB data collected over more than a decade of operation with the \textit{Fermi}-LAT $γ$-ray space telescope, the exact contribution of SFGs to the EGB remains unsettled. In this study, we model the $γ$-ray emission from SFG populations and demonstrate that such emission can be characterized by just a small number of physically-motivated parameters. We further show that source populations would leave anisotropic signatures in the EGB, which could be used to yield information about the underlying properties, dynamics and evolution of CR-rich SFGs.
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