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

## TL;DR

This paper investigates the properties of hybrid plasma coronae in AGN, showing that nonthermal particles influence temperature regulation via pair production, aligning models more closely with observed X-ray spectra.

## Contribution

It introduces a model of hybrid plasma coronae in AGN, incorporating nonthermal particles and pair production effects, advancing understanding of coronal physics.

## Key findings

- Nonthermal particles lower coronal temperature.
- Hybrid plasma models better match observed spectra.
- Pair production constrains coronal temperature range.

## 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.