发表机构
Universität Innsbruck（因斯布鲁克大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用费米LAT 15年数据，分析LMC中Hα选择的超巨壳层的伽马射线发射，探测到7个显著源，光谱倾向强子起源，其贡献占总弥散发射的41%。
AI 中文摘要
大麦哲伦云（LMC）是我们银河系的卫星星系，被认为是研究弥散伽马射线发射的极佳目标。观测表明，弥散发射与LMC的大尺度和小尺度结构有关。特别是，有人提出一些较小尺度的明亮弥散发射与先前基于Hα图像识别的超巨壳层（SGSs）重合。我们利用费米大面积望远镜超过15年的观测数据，在300 MeV-300 GeV能量范围内分析了来自LMC的伽马射线发射。对LMC的弥散发射成分进行了专门的空间和光谱分析。特别是，我们使用现象学方法详细评估了SGSs的发射，并建立了它们对应的伽马射线发射空间模板。在小尺度延展发射的分析中，我们以超过5σ的显著性探测到七个Hα选择的SGSs。SGSs内部嵌套的发射结构表现为非高斯特征，很可能是由超新星遗迹激波集合调制的宇宙线分布所致。大多数SGS区域的伽马射线发射光谱支持强子起源。对于LMC盘的大尺度弥散发射，我们的结果表明强子和轻子诱导发射之间存在相互作用。明亮SGSs的宇宙线质子能量密度比LMC盘中的高3-10倍。在所有SGSs中，SGS 2被探测到是最显著的发射区域。基于我们在LMC的Hα选择的SGSs中探测到的伽马射线过剩发射，我们估计它们对LMC中总弥散伽马射线发射的贡献处于不可忽视的41%水平。
英文摘要
The Large Magellanic Cloud (LMC), a satellite galaxy of our Milky Way, is considered to be a very good target for investigations of diffuse gamma-ray emission. Observations have shown that diffuse emissions are related to the large- and small-scale structures of the LMC. Particularly, it has been suggested that some of the small-scale bright diffuse emissions coincide with supergiant shells (SGSs) previously identified based on H$α$ images. We analyzed the gamma-ray emission from the LMC using more than 15 years of observations with the \textit{Fermi} Large Area Telescope in the energy range of 300$\,$MeV-300$\,$GeV. A dedicated spatial and spectral analysis was made for diffuse emission components of the LMC. Particularly, we evaluated the emissions from SGSs in detail using phenomenological approaches, and we established their corresponding spatial templates for gamma-ray emission. In the analysis of small-scale extended emissions, we detected seven H$α$-selected SGSs at a significance of more than $5σ$. The emission structure nested inside the SGSs appears to be a non-Gaussian feature and is very likely due to a modulated cosmic-ray distribution by an ensemble of supernova remnant shocks. The spectra of the gamma-ray emission for most SGS regions favor a hadronic origin. For the large-scale diffuse emission from the LMC disk, our results suggest an interplay of hadron- and lepton-induced emission. The cosmic-ray proton energy density derived for bright SGSs is 3-10 times higher than that in the LMC disk. SGS$\,2$ was detected to be the most significant emission region among all SGSs. Based on the gamma-ray excess emission we detected in H$α$-selected SGSs in the LMC, we estimate that their contribution to the total diffuse gamma-ray emission in the LMC is at a non-negligible 41\% level.
Journal refA&A, 713, A236 (2026)
DOI：10.1051/0004-6361/202660237
