Murase Kohta, Kimura Shigeo S, Mészáros Peter
Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Department of Astronomy & Astrophysics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Phys Rev Lett. 2020 Jul 3;125(1):011101. doi: 10.1103/PhysRevLett.125.011101.
Mysteries about the origin of high-energy cosmic neutrinos have deepened by the recent IceCube measurement of a large diffuse flux in the 10-100 TeV range. Based on the standard disk-corona picture of active galactic nuclei (AGN), we present a phenomenological model enabling us to systematically calculate the spectral sequence of multimessenger emission from the AGN coronae. We show that protons in the coronal plasma can be stochastically accelerated up to PeV energies by plasma turbulence, and find that the model explains the large diffuse flux of medium-energy neutrinos if the cosmic rays carry only a few percent of the thermal energy. We find that the Bethe-Heitler process plays a crucial role in connecting these neutrinos and cascaded MeV gamma rays, and point out that the gamma-ray flux can even be enhanced by the reacceleration of secondary pairs. Critical tests of the model are given by its prediction that a significant fraction of the MeV gamma-ray background correlates with ∼10 TeV neutrinos, and nearby Seyfert galaxies including NGC 1068 are promising targets for IceCube, KM3Net, IceCube-Gen2, and future MeV gamma-ray telescopes.
近期冰立方探测器对10 - 100 TeV能量范围内的大量弥散通量的测量，加深了高能宇宙中微子起源的谜团。基于活动星系核（AGN）的标准盘-冕模型，我们提出了一个唯象模型，使我们能够系统地计算AGN冕的多信使发射光谱序列。我们表明，日冕等离子体中的质子可以通过等离子体湍流被随机加速到PeV能量，并发现如果宇宙射线仅携带百分之几的热能，该模型就能解释中能中微子的大量弥散通量。我们发现贝特-海特勒过程在连接这些中微子和级联MeV伽马射线中起着关键作用，并指出次级对的再加速甚至可以增强伽马射线通量。该模型的关键检验在于其预测，即相当一部分MeV伽马射线背景与~10 TeV中微子相关，包括NGC 1068在内的附近赛弗特星系是冰立方、KM3Net、冰立方-第二代以及未来MeV伽马射线望远镜的有希望的目标。
