The GeV-TeV Galactic gamma-ray diffuse emission - I. Uncertainties in the predictions of the hadronic component
The GeV-TeV Galactic gamma-ray diffuse emission - I. Uncertainties in the predictions of the hadronic component
复制标题
GeV-TeV 银河伽马射线扩散发射 - I. 强子成分预测的不确定性
DOI：
10.1051/0004-6361/201116647
复制
发表时间：
2011
影响因子：
6.5
通讯作者：
P. Salati
中科院分区：
文献类型：
--
作者：
T. Delahaye;A. Fiasson;M. Pohl;P. Salati
银河伽马射线漫发射目前被费米卫星以前所未有的精度观测到，能量范围在GeV-TeV。了解这个成分是至关重要的，因为它为许多不同的信号提供了背景，例如河外源或湮灭暗物质。现在是重新调查它是如何计算的，并评估可能影响预测准确性的各种不确定性的时候了。银河系的γ射线漫发射主要是由几个GeV以上的宇宙线原色撞击星际物质相互作用产生的。通过探索各种潜在的不确定性来源，推导出该分量的理论误差。特别注意宇宙射线的传播。核截面、地球上的质子和氦通量、超新星遗迹的银河系径向轮廓和氢分布也会严重影响信号。宇宙射线物种在整个银河系的传播是在一个半解析的两区扩散/对流模型的框架。这允许将由硼-碳数据设置的约束转换为扩散排放的理论不确定性。新的去卷积的HI和CO的天空图也被用来得到银河系内的氢分布。宇宙线扩散晕的厚度被发现有一个显着的影响银河伽玛射线扩散发射，而扩散和对流之间的相互作用对信号的影响不大。与核截面和地球上的初级宇宙线通量有关的不确定性很大。超新星遗迹沿着银河平面的径向分布被证明是一个关键因素。正如预期的那样，这些预测对银河系内氢的空间分布非常敏感。
The Galactic gamma-ray diffuse emission is currently observed in the GeV-TeV energy range with unprecedented accuracy by the Fermi satellite. Understanding this component is crucial as it provides a background to many different signals such as extragalactic sources or annihilating dark matter. It is timely to reinvestigate how it is calculated and to assess the various uncertainties which are likely to affect the accuracy of the predictions. The Galactic gamma-ray diffuse emission is mostly produced above a few GeV by the interactions of cosmic ray primaries impinging on the interstellar material. The theoretical error on that component is derived by exploring various potential sources of uncertainty. Particular attention is paid to cosmic ray propagation. Nuclear cross sections, the proton and helium fluxes at the Earth, the Galactic radial profile of supernova remnants and the hydrogen distribution can also severely affect the signal. The propagation of cosmic ray species throughout the Galaxy is described in the framework of a semi-analytic two-zone diffusion/convection model. This allows to convert the constraints set by the boron-to-carbon data into a theoretical uncertainty on the diffuse emission. New deconvolutions of the HI and CO sky maps are also used to get the hydrogen distribution within the Galaxy. The thickness of the cosmic ray diffusive halo is found to have a significant effect on the Galactic gamma-ray diffuse emission while the interplay between diffusion and convection has little influence on the signal. The uncertainties related to nuclear cross sections and to the primary cosmic ray fluxes at the Earth are significant. The radial distribution of supernova remnants along the Galactic plane turns out to be a key ingredient. As expected, the predictions are extremely sensitive to the spatial distribution of hydrogen within the Milky Way.