High-energy neutrinos and gamma rays from winds and tori in active galactic nuclei

Susumu Inoue, Matteo Cerruti, Kohta Murase, Ruo-Yu Liu

Submitted on 5 July 2022


Powerful winds with wide opening angles, likely driven by accretion disks around black holes (BHs), are observed in the majority of active galactic nuclei (AGN) and can play a crucial role in AGN and galaxy evolution. If protons are accelerated in the wind near the BH via diffusive shock acceleration, p-gamma processes with AGN photons can generate neutrinos as well as pair cascade emission from the gamma-ray to radio bands. The TeV neutrinos tentatively detected by IceCube from the obscured Seyfert galaxy NGC 1068 can be interpreted consistently if the shock velocity is appreciably lower than the local escape velocity, which may correspond to a failed, line-driven wind that is physically well motivated. Although the p-gamma-induced cascade is gamma-gamma-attenuated above a few MeV, it can still contribute significantly to the sub-GeV gamma rays observed from NGC 1068. At higher energies, gamma rays can arise via pp processes from a shock where an outgoing wind impacts the obscuring torus, along with some observable radio emission. Tests and implications of this model are discussed. Neutrinos and gamma rays may offer unique probes of AGN wind launching sites, particularly for objects obscured in other forms of radiation.


Comment: 13 pages including supplemental material, for submission to PRL

Subjects: Astrophysics - High Energy Astrophysical Phenomena; Astrophysics - Cosmology and Nongalactic Astrophysics