arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1603.04074astro-ph.HE
收藏

关于超高能宇宙射线及其合成γ射线

On ultra high energy cosmic rays and their resultant gamma rays

Eyal Gavish, David Eichler

摘要:

费米大面积望远镜(Fermi LAT)合作最近报告了对$100\mbox{MeV}$和$820\mbox{GeV}$之间各向同性河外伽马射线背景(EGRB)光谱的50个月测量。超高能宇宙射线(UHECR)质子与宇宙微波背景(CMB)光子相互作用,并产生能量为$10\mbox{MeV}\mbox{-}1\mbox{TeV}$的级联光子,这些光子对EGRB通量有贡献。我们研究了七种可能的演化模型UHECR,并发现UHECR源,恒星形成率(SFR),中低光度活动星系核类型-1($L = 10^{43.5}\mbox{erg sec}^{-1}$在$[0.5\mbox{-}2]\mbox{KeV}$带),BL Lacertae对象(BL Lacs)的演变是最可接受的所观察到的EGRB所施加的限制。其他可能性产生过多的二次$γ$辐射。在所有情况下,衰变的暗物质的贡献都改善了高能时的拟合,但尚未解决的耀变体的贡献(它将使衰变的暗物质的作用最小)可能还提供了另一种改进。正如Ajello等人(2015)最近声称的那样,整个EGRB都可以安装可分辨但尚未分辨的耀变体的可能性,将在EGRB中留下很少的空间来容纳来自河外UHECR生产的$γ$ -射线,即使对于许多源演化速率,否则是可以接受的。我们发现,在假设的UHECR主要是质子,有没有足够的空间产生河外UHECR与AGN,GRB,甚至SFR源演化。另一方面,发展为BL Lac的源将产生少得多的次级$γ$辐射,并且将仍然是UHECR的可行源,只要它们占主导地位。

英文摘要:

The Fermi Large Area Telescope (Fermi LAT) collaboration has recently reported on 50 months of measurements of the isotropic Extragalactic Gamma Ray Background (EGRB) spectrum between $100\mbox{MeV}$ and $820\mbox{GeV}$. Ultrahigh Energy Cosmic Ray (UHECR) protons interact with the Cosmic Microwave Background (CMB) photons and produce cascade photons of energies $10\mbox{MeV}\mbox{-}1\mbox{TeV}$ that contribute to the EGRB flux. We examine seven possible evolution models for UHECRs and find that UHECR sources that evolve as the Star Formation Rate (SFR), medium low luminosity active galactic nuclei type-1 ($L = 10^{43.5}\mbox{erg sec}^{-1}$ in the $[0.5\mbox{-}2]\mbox{KeV}$ band), and BL Lacertae objects (BL Lacs) are the most acceptable given the constraints imposed by the observed EGRB. Other possibilities produce too much secondary $γ$-radiation. In all cases, the decaying dark matter contribution improves the fit at high energy, but the contribution of still unresolved blazars, which would leave the smallest role for decaying dark matter, may yet provide an alternative improvement. The possibility that the entire EGRB can be fitted with resolvable but not-yet-resolved blazars, as recently claimed by Ajello et al. (2015), would leave little room in the EGRB to accommodate $γ$-rays from extragalactic UHECR production, even for many source evolution rates that would otherwise be acceptable. We find that, under the assumption of UHECRs being mostly protons, there is not enough room for producing extragalactic UHECRs with AGN, GRB, or even SFR source evolution. Sources that evolve as BL Lacs on the other hand, would produce much less secondary $γ$-radiation and would remain a viable source of UHECRs, provided that they dominate.

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。

↑