Hostname: page-component-586b7cd67f-t8hqh Total loading time: 0 Render date: 2024-11-20T06:39:24.307Z Has data issue: false hasContentIssue false

X-ray emission from hot accretion flows

Published online by Cambridge University Press:  25 July 2014

Andrzej Niedźwiecki
Affiliation:
Department of Astrophysics, University of Łódź, Pomorska 149/153, 90-236 Łódź, Poland email: [email protected]
Fu-Guo Xie
Affiliation:
Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, China email: [email protected]
Agnieszka Stȩpnik
Affiliation:
Department of Astrophysics, University of Łódź, Pomorska 149/153, 90-236 Łódź, Poland email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

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.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2014 

References

Beckmann, V., et al. 2011 AA, 531, 70CrossRefGoogle Scholar
Brenneman, L., et al. 2012, ApJ, 744, 13Google Scholar
Donato, D., Sambruna, R. M., & Gliozzi, M. 2004 ApJ, 617, 915CrossRefGoogle Scholar
Emmanoulopoulos, D., et al. 2012, MNRAS, 424, 1327Google Scholar
Gu, M. & Cao, X. 2009, MNRAS, 399, 349CrossRefGoogle Scholar
Lubiński, P., et al. 2010, MNRAS, 408, 1851Google Scholar
Narayan, R. & McClintock, J. E. 2004, New Astron. Revs, 51, 733Google Scholar
Niedźwiecki, A., Xie, F.-G., & Stȩpnik, A. 2013, MNRAS, 432, 1576Google Scholar
Niedźwiecki, A., Xie, F. G., & Zdziarski, A. 2012, MNRAS, 420, 1195Google Scholar
Xie, F.-G., et al. 2010, MNRAS, 403, 170Google Scholar
Yamada, S., et al. 2009, PASJ, 61, 309CrossRefGoogle Scholar
Yang, , et al. 2009, ApJ, 691, 131Google Scholar
Yuan, F. & Zdziarski, A. 2004, MNRAS, 354, 953CrossRefGoogle Scholar
Zhou, X.-L. & Zhang, S.-N. 2010, ApJ (Letters), 713, L11Google Scholar