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arXiv 1003.1496astro-ph.HE
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用Fermi-LAT限制UHECR和宇宙成因中微子

Restricting UHECRs and cosmogenic neutrinos with Fermi-LAT

V. Berezinsky, A. Gazizov, M. Kachelriess, S. Ostapchenko

摘要:

超高能宇宙射线(UHECR)质子与宇宙微波背景(CMB)相互作用产生UHE电子和伽马射线,其继而在CMB和红外光子上引发电磁级联。结果,在$E\lsim 100$ GeV的能量范围内积累了漫射各向同性伽马辐射的背景。费米-LAT合作最近报告了对河外弥漫背景的测量,发现它比EGRET以前测量的强度更小,更柔软。我们表明,这一新的结果约束UHECR模型和宇宙成因中微子的流量。特别是,它排除了现有中微子实验可检测到的宇宙成因中微子通量的模型,而下一代探测器,如JEM-EUSO只能观察极端参数的中微子。

英文摘要:

Ultrahigh energy cosmic ray (UHECR) protons interacting with the cosmic microwave background (CMB) produce UHE electrons and gamma-rays that in turn initiate electromagnetic cascades on CMB and infrared photons. As a result, a background of diffuse isotropic gamma radiation is accumulated in the energy range $E\lsim 100$ GeV. The Fermi-LAT collaboration has recently reported a measurement of the extragalactic diffuse background finding it less intense and softer than previously measured by EGRET. We show that this new result constrains UHECR models and the flux of cosmogenic neutrinos. In particular, it excludes models with cosmogenic neutrino fluxes detectable by existing neutrino experiments, while next-generation detectors as e.g. JEM-EUSO can observe neutrinos only for extreme parameters.

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