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arXiv 2201.09479astro-ph.HE
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AGN喷注的重子负载因子的限制:来自后发座星系团gamma-ray发射的启示

Constraining the baryon loading factor of AGN jets: implication from the gamma-ray emission of the Coma cluster

Xin-Yue Shi, Yi Zhang, Ruo-Yu Liu, Xiang-Yu Wang

摘要:

高能宇宙射线可以在活动星系核(AGN)的相对论喷流中被加速,而活动星系核是由超大质量黑洞提供能量的。从吸积黑洞到相对论性CR重子的重子装载效率目前还没有得到很好的观测约束。由于活动星系核喷注注入的重子被完全限制在星系团中,并通过强子过程与团内介质充分相互作用,产生弥散的$γ$射线,因此我们认为星系团的$γ$射线辐射可以用来研究活动星系核喷注的重子装载因子.我们研究了CR在星系团中的传播,计算了AGN不同注入率下的γ射线在星系团中的径向分布。通过与$Fermi$ -LAT和VERITAS测量的后发座星系团的$γ$射线通量和上限值的比较,我们发现平均重子装载因子{(定义为引力能转化为相对论粒子的效率)}的上限为$η_{p, \mathrm{grav}} < 0.1$ .上限是远远低于所需的帐户在传统的耀变体模型中的扩散中微子通量。

英文摘要:

High-energy cosmic rays (CRs) can be accelerated in the relativistic jets of Active Galactic Nuclei (AGNs) powered by supermassive black holes. The baryon loading efficiency onto relativistic CR baryons from the accreting black holes is poorly constrained by observations so far. In this paper, we suggest that the $γ$-ray emission of galaxy clusters can be used to study the baryon loading factor of AGN jets, since CRs injected by AGN jets are completely confined in the galaxy clusters and sufficiently interact with intra-cluster medium via hadronic process, producing diffuse $γ$-rays. We study the propagation of CRs in the galaxy clusters and calculate the radial distribution of the gamma-rays in the galaxy cluster with different injection rates from AGNs. By comparison with the $γ$-ray flux and upper limits of the Coma cluster measured by $Fermi$-LAT and VERITAS, we find the upper limit of the average baryon loading factor {(defined as the efficiency with which the gravitational energy is converted into relativistic particles)} to be $η_{p, \mathrm{grav}} < 0.1$. The upper limit is much lower than that required to account for diffuse neutrino flux in the conventional blazar models.

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