• DOI:10.1017/S1743921314004037
• Corpus ID: 118592894

X-ray emission from hot accretion flows

@article{Niedwiecki2013XrayEF,
  title={X-ray emission from hot accretion flows},
  author={Andrzej Niedźwiecki and Fuguo Xie and Agnieszka Stepnik},
  journal={Proceedings of the International Astronomical Union},
  year={2013},
  volume={9},
  pages={266 - 269}
}

• A. Niedźwiecki, F. Xie, A. Stepnik
• Published 1 October 2013
• Physics
• Proceedings of the International Astronomical Union

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.