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arXiv · 1404.1219

X-ray emission from hot accretion flows

Andrzej Niedzwiecki·Fu-Guo Xie·Agnieszka Stepnik
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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.

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Andrzej Niedzwiecki, Fu-Guo Xie, Agnieszka Stepnik. 2014-04-04. X-ray emission from hot accretion flows. https://arxiv.org/abs/1404.1219

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