Gamma Rays from Cosmic-Ray Proton Scattering in AGN Jets: the Intra-Cluster Gas vastly outshines Dark Matter
Gamma Rays from Cosmic-Ray Proton Scattering in AGN Jets: the Intra-Cluster Gas vastly outshines Dark Matter
复制标题
AGN 喷流中宇宙射线质子散射产生的伽马射线：星团内气体远远超过暗物质
DOI：
10.1088/1475-7516/2013/04/012
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
M. Gorchtein
中科院分区：
文献类型：
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作者：
S. Profumo;Lorenzo Ubaldi;M. Gorchtein
活动星系核（AGN）拥有包含高能电子和质子的强大喷流。活动星系核及其喷流所处的天体物理环境的特征是暗物质（DM）和星系团内介质（ICM）气体的高浓度。当高能喷流粒子穿过DM和ICM时，弹性和非弹性散射过程通常导致最终态光子的产生。正如Bloom和威尔斯（1998）首先设想的那样，以及我们和其他人最近指出的那样，电子从DM的散射可能导致潜在的可检测的伽马射线信号，质子的部分子水平贡献提供了更暗淡的前景。最近，Chang等人认为，考虑到强子化和簇射的光子，实际的光子通量大大增加。在这里，我们指出，质子喷流必须是高度准直的，与这些研究中有时采用的简单的斑点几何喷流模型所预测的相反，否则它们将从与ICM核子的非弹性碰撞中产生非常大的光子通量，这将使DM的信号黯然失色许多数量级，对于几乎任何合理的ICM和DM密度分布。
Active Galactic Nuclei (AGN) host powerful jets containing high-energy electrons and protons. The astrophysical environment where AGNs and their jets are found is characterized by large concentrations of both dark matter (DM) and intra-cluster medium (ICM) gas. As the high-energy jet particles transverse the DM and the ICM, elastic and inelastic scattering processes generically lead to the production of final-state photons. As first envisioned by Bloom and Wells (1998), and as more recently pointed out by us and others, the scattering of electrons off of DM could lead to a potentially detectable gamma-ray signal, with the parton-level contribution from protons offering dimmer perspectives. Recently, Chang et al. argued that taking into account photons from hadronization and showering, the actual photon flux is substantially increased. Here, we point out that the proton-jets have to be highly collimated, contrary to what predicted by simple blob-geometry jet-models sometimes employed in these studies, otherwise they would produce a very large flux of photons from inelastic collisions with ICM nucleons, which would outshine by many orders of magnitude the signal from DM, for almost any reasonable ICM and DM density profiles.