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arXiv · 1701.06774

Properties of AGN coronae in the NuSTAR era II: hybrid plasma

A. C. Fabian·A. Lohfink·R. Belmont·J. Malzac·P. Coppi
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Abstract

The corona, a hot cloud of electrons close to the centre of the accretion disc, produces the hard X-ray power-law continuum commonly seen in luminous Active Galactic Nuclei (AGN). The continuum has a high-energy turnover, typically in the range of one to several 100 keV and is suggestive of Comptonization by thermal electrons. We are studying hard X-ray spectra of AGN obtained with NuSTAR after correction for X-ray reflection and under the assumption that coronae are compact, being only a few gravitational radii in size as indicated by reflection and reverberation modelling. Compact coronae raise the possibility that the temperature is limited and indeed controlled by electron-positron pair production, as explored earlier (Paper I). Here we examine hybrid plasmas in which a mixture of thermal and nonthermal particles is present. Pair production from the nonthermal component reduces the temperature leading to a wider temperature range more consistent with observations.

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A. C. Fabian, A. Lohfink, R. Belmont, J. Malzac, P. Coppi. 2017-01-24. Properties of AGN coronae in the NuSTAR era II: hybrid plasma. https://doi.org/10.1093/mnras%2Fstx221

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