论文标题

时空传播域中费米伽玛射线天空的多组分成像

Multi-Component Imaging of the Fermi Gamma-ray Sky in the Spatio-spectral Domain

论文作者

Platz, Lukas I., Knollmüller, Jakob, Arras, Philipp, Frank, Philipp, Reinecke, Martin, Jüstel, Dominik, Enßlin, Torsten A.

论文摘要

我们基于费米大面积望远镜(LAT)数据,在0.56-316 GEV范围内执行了两个不同的伽玛射线天空时空重建。两者都描述了由分散发射和点源组成的天空亮度。第一个模型需要最小的假设,并提供无模板重建作为参考。它利用空间和光谱相关性来区分不同的组件。第二个模型是物理信息的,并进一步区分了辐射和松弛起源的弥漫性发射。为此,我们假设参数,但在空间上有变化的能量光谱,以区分过程和使用热银河灰尘观测,以指示HADRONIC相互作用的首选位点。为了说明仪器效应,我们在整个观察过程中对望远镜的点分散,能量分散和暴露进行建模。重建问题被提出为贝叶斯推理任务,这是通过变异推理解决的。我们将伽马射线通量分解为弥漫性和点状排放,以及分散的排放分解为多种物理动机的成分。弥漫性分解提供了银河系发射发射的前所未有的视图。它显示了费米气泡及其在高保真度和其他表现出强宇宙射线电子内容物(例如内星系中厚磁盘和流出区域的厚度磁盘)中的光谱变化。此外,我们报告了北部外部气泡共同空间中的硬谱伽玛射线弧,并与Erosita合作报告的X射线弧相同。我们所有的空间谱天空重建及其不确定性量化都可以公开使用。

We perform two distinct spatio-spectral reconstructions of the gamma-ray sky in the range of 0.56-316 GeV based on Fermi Large Area Telescope (LAT) data. Both describe the sky brightness to be composed of a diffuse-emission and a point-source component. The first model requires minimal assumptions and provides a template-free reconstruction as a reference. It makes use of spatial and spectral correlations to distinguish between the different components. The second model is physics-informed and further differentiates between diffuse emission of hadronic and leptonic origin. For this, we assume parametric, but spatially varying energy spectra to distinguish between the processes and use thermal Galactic dust observations to indicate the preferred sites of hadronic interactions. To account for instrumental effects we model the point-spread, the energy dispersion, and the exposure of the telescope throughout the observation. The reconstruction problem is formulated as a Bayesian inference task, that is solved by variational inference. We show decompositions of the Gamma-ray flux into diffuse and point-like emissions, and of the diffuse emissions into multiple physically motivated components. The diffuse decomposition provides an unprecedented view of the Galactic leptonic diffuse emission. It shows the Fermi bubbles and their spectral variations in high fidelity and other areas exhibiting strong cosmic ray electron contents, such as a thick disk in the inner Galaxy and outflow regions. Furthermore, we report a hard spectrum gamma ray arc in the northern outer bubble co-spatial with the reported X-ray arc by the eROSITA collaboration. All our spatio-spectral sky reconstructions and their uncertainty quantification are publicly available.

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