Hadronic origin of multi-TeV gamma rays and neutrinos from low-luminosity active galactic nuclei: Implications of past activities of the Galactic center
Hadronic origin of multi-TeV gamma rays and neutrinos from low-luminosity active galactic nuclei: Implications of past activities of the Galactic center
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DOI：
10.1103/physrevd.92.023001
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发表时间：
2015-06
影响因子：
5
通讯作者：
Y. Fujita;S. Kimura;K. Murase
中科院分区：
文献类型：
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作者：
Y. Fujita;S. Kimura;K. Murase
低光度活动星系核(LLAGNs)中的辐射无效吸积流(RIAF)被认为是宇宙射线和中微子源，它们可能对观测到的弥散中微子强度有很大贡献。我们发现，这一场景自然地预测了银河系中心周围的强子多TeV伽马射线过剩。在人马座A星座的Riaf中加速的质子逃逸，并与Sgr A周围的致密分子气体相互作用，这被称为中央分子带(CMZ)，并产生伽马射线和中微子。基于与IceCube数据兼容的理论模型，我们计算了CMZ的伽马能谱，发现如果SgrA过去如各种观测所表明的那样比现在更活跃，那么高能立体系统可能已经探测到了具有$1$TeV的伽马射线。我们的模型预测中微子应该来自CMZ，其光谱类似于伽马射线光谱。我们还表明，对于一些拥有LLAGNs的附近星系来说，预计会出现这样的伽马射线过剩。
Radiatively inefficient accretion flows (RIAFs) in low-luminosity active galactic nuclei (LLAGNs) have been suggested as cosmic-ray and neutrino sources that may largely contribute to the observed diffuse neutrino intensity. We show that this scenario naturally predicts hadronic multi-TeV gamma-ray excesses around Galactic centers. The protons accelerated in the RIAF in Sagittarius A$^*$ (Sgr A$^*$) escape and interact with dense molecular gas surrounding Sgr A$^*$, which is known as the central molecular zone (CMZ), and produce gamma rays as well as neutrinos. Based on a theoretical model that is compatible with the IceCube data, we calculate gamma-ray spectra of the CMZ and find that the gamma rays with $\gtrsim 1$ TeV may have already been detected with the High Energy Stereoscopic System, if Sgr A$^*$ was more active in the past than it is today as indicated by various observations. Our model predicts that neutrinos should come from the CMZ with a spectrum similar to the gamma-ray spectrum. We also show that such a gamma-ray excess is expected for some nearby galaxies hosting LLAGNs.