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arXiv 1111.1636astro-ph.HE
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gamma-ray梯度问题的另一种解决方案

An alternative solution to the gamma-ray Gradient problem

Daniele Gaggero, Carmelo Evoli, Dario Grasso, Luca Maccione

摘要:

费米-LAT合作最近证实了EGRET的发现,即观测到的银河系伽马射线漫发射的纵向剖面与GALPROP计算的不一致,GALPROP假设宇宙射线是由银河系超新星遗迹产生的。精确的费米-LAT测量使得这种异常很难用传统的扩散方案来解释。在这里,我们使用DRAGON数值扩散代码来实现一个物理动机的情况下,扩散系数是空间相关的源密度。我们表明,在这些条件下,我们能够再现所观察到的平坦的发射率分布在外星系,而不需要改变源项,扩散晕高度,或CO-H2转换因子(XCO)相对于他们的首选值/分布。我们还表明,我们的模型与Fermi-LAT测量的伽马射线纵向剖面兼容,并且仍然对所有观察到的次级与初级比率(例如B/C和反质子/质子)提供了令人满意的拟合。

英文摘要:

The Fermi-LAT collaboration recently confirmed EGRET finding of a discrepancy between the observed longitudinal profile of gamma-ray diffuse emission from the Galaxy and that computed with GALPROP assuming that cosmic rays are produced by Galactic supernova remnants. The accurate Fermi-LAT measurements make this anomaly hardly explainable in terms of conventional diffusion schemes. Here we use DRAGON numerical diffusion code to implement a physically motivated scenario in which the diffusion coefficient is spatially correlated to the source density. We show that under those conditions we are able to reproduce the observed flat emissivity profile in the outer Galaxy with no need to change the source term, the diffusion halo height, or the CO-H2 conversion factor (XCO) with respect to their preferred values/distributions. We also show that our models are compatible with gamma-ray longitudinal profiles measured by Fermi-LAT, and still provide a satisfactory fit of all observed secondary-to-primary ratios, such as B/C and antiprotons/protons.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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