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arXiv 1005.2620astro-ph.HEhep-ph
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Fermi-LAT扩散光子通量测量后的GZK中微子

GZK Neutrinos after the Fermi-LAT Diffuse Photon Flux Measurement

M. Ahlers, L. A. Anchordoqui, M. C. Gonzalez-Garcia, F. Halzen, Subir Sarkar

摘要:

宇宙成因中微子起源于宇宙线质子与宇宙微波背景(CMB)的光强子相互作用。中微子的产生速率可以通过伴随的电子、正电子和伽马射线来限制,这些电子、正电子和伽马射线快速地级联在CMB和星系际磁场上,以降低能量并产生GeV-TeV区域的伽马射线背景。质子产生的贝特-海特勒对也有助于级联,并可以在河外宇宙射线开始以相对较低的“交叉”能量主导银河系成分的模型中收紧中微子约束。我们调查这个问题的光最近的费米-LAT测量的弥漫河外伽马射线背景,并说明了一个适合HiRes光谱如何预测宇宙成因中微子通量的全质子模型的交叉能量的变化。当应用γ射线束缚时,中微子通量需要更小,但是如果适当考虑宇宙射线测量的能量不确定性,这样的模型仍然与HiRes和Fermi-LAT一致。目前允许的通量是在冰立方中微子望远镜和其他专门的无线电实验的范围内。

英文摘要:

Cosmogenic neutrinos originate from photo-hadronic interactions of cosmic ray protons with the cosmic microwave background (CMB). The neutrino production rate can be constrained through the accompanying electrons, positrons and gamma-rays that quickly cascade on the CMB and intergalactic magnetic fields to lower energies and generate a gamma ray background in the GeV-TeV region. Bethe-Heitler pair production by protons also contributes to the cascade and can tighten the neutrino constraints in models where extragalactic cosmic rays begin to dominate over the galactic component at a relatively low "crossover" energy. We investigate this issue in the light of the recent Fermi-LAT measurements of the diffuse extragalactic gamma ray background and illustrate by a fit to the HiRes spectrum how the prediction of the cosmogenic neutrino flux in all-proton models varies with the crossover energy. The neutrino flux is required to be smaller when the gamma-ray bound is applied, nevertheless such models are still consistent with HiRes and Fermi-LAT if one properly takes into account the energy uncertainty of cosmic ray measurements. The presently allowed flux is within reach of the IceCube neutrino telescope and other dedicated radio experiments.

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