Nonthermal processes in hot accretion flows onto supermassive black holes: An inhomogeneous model

Abstract

Context. Many low-redshift active galactic nuclei harbor a supermassive black hole accreting matter at low or medium rates. At such rates, the accretion flow usually consists of a cold optically thick disk, plus a hot, low density, collisionless corona. In the latter component, charged particles can be accelerated to high energies by various mechanisms. Aims. We aim to investigate, in detail, nonthermal processes in hot accretion flows onto supermassive black holes, covering a wide range of accretion rates and luminosities. Methods. We developed a model consisting of a thin Shakura-Sunyaev disk plus an inner hot accretion flow or corona, modeled as a radiatively inefficient accretion flow, where nonthermal processes take place. We solved the transport equations for relativistic particles and estimated the spectral energy distributions resulting from nonthermal interactions between the various particle species and the fields in the source. Results. We covered a variety of scenarios, from low accretion rates up to 10% of the Eddington limit, and identified the relevant cooling mechanisms in each case. The presence of hadrons in the hot flow is decisive for the spectral shape, giving rise to secondary particles and gamma-ray cascades. We applied our model to the source IC 4329A, confirming earlier results which showed evidence of nonthermal particles in the corona.

Revisiting the constraints on primordial black hole abundance with the isotropic gamma ray background

“…We take into account the simulated IGRB of Kimura et al [22] into the analysis for PBH constraint, and the model from [18] is also discussed in Sec. V. The former seems more realistic [48,49], where the thermal electrons inside hot accretion flows naturally emit soft gamma-rays via synchrotron self-Compton processes.…”

Advancing the Landscape of Multimessenger Science in the Next Decade

“…These observations not only suggest that AGN coronae possess non-thermal activity but also enable us to determine the size and the magnetic field of AGN coronae [229]. By combining recent non-thermal millimeter and thermal X-ray observations, multi-messenger signals from AGN coronae have been revisited [230,231]. These models can reproduce the hint of neutrino signals from NGC 1068 [206].…”

Search for neutrino emission from cores of active galactic nuclei

“…Alternatively, CRs can be accelerated in the core regions of AGN, inside the accretion disk or the corona surrounding it [17,[25][26][27][28][29][30][31][32][33][34]. Neutrinos produced in the interactions of these CRs would escape freely, while coproduced GeV and TeV gamma rays would be reprocessed to lower energies in the intense radiation field of the accretion disk before escaping.…”