X-ray emission from hot accretion flows
Abstract
Radiatively inefficient, hot accretion flows are widely considered as a relevant accretion mode in low-luminosity AGNs. We study spectral formation in such flows using a refined model with a fully general relativistic description of both the radiative (leptonic and hadronic) and hydrodynamic processes, as well as with an exact treatment of global Comptonization. We find that the X-ray spectral index--Eddington ratio anticorrelation as well as the cut-off energy measured in the best-studied objects favor accretion flows with rather strong magnetic field and with a weak direct heating of electrons. Furthermore, they require a much stronger source of seed photons than considered in previous studies. The nonthermal synchrotron radiation of relativistic electrons seems to be the most likely process capable of providing a sufficient flux of seed photons. Hadronic processes, which should occur due to basic properties of hot flows, provide an attractive explanation for the origin of such electrons.
Cite
@article{arxiv.1404.1219,
title = {X-ray emission from hot accretion flows},
author = {Andrzej Niedzwiecki and Fu-Guo Xie and Agnieszka Stepnik},
journal= {arXiv preprint arXiv:1404.1219},
year = {2014}
}
Comments
To be published in "Multiwavelength AGN surveys and studies", Proceedings of IAU Symposium No. 304, 2013, eds. A. Mickaelian, F. Aharonian, D. Sanders