# The coronal temperature of NGC 4388 and NGC 2110 measured with INTEGRAL

## TL;DR

This study measures the coronal temperatures of two active galactic nuclei using INTEGRAL, XMM-Newton, and NuSTAR data, revealing high-energy cut-offs and thermal properties consistent with pair production regulation.

## Contribution

It provides new measurements of coronal temperatures and high-energy cut-offs for NGC 4388 and NGC 2110 using combined X-ray observations, highlighting the importance of high-energy data.

## Key findings

- Coronal temperatures are approximately 80 keV and 75 keV.
- High-energy cut-offs are 200 keV and 320 keV.
- Results support pair production as a plasma thermostat.

## Abstract

We aim to measure the physical properties of the hot X-ray corona of two active galactic nuclei, NGC 4388 and NGC 2110. We analysed the hard X-ray (20-300 keV) INTEGRAL spectrum in conjunction with archival XMM-Newton and NuSTAR data. The X-ray spectrum of both sources is phenomenologically well described by an absorbed cut-off power law. In agreement with previous results, we find no evidence of a Compton reflection component in these sources. We obtain a high-energy cut-off of $200^{+75}_{-40}$ keV for NGC 4388 and $320^{+100}_{-60}$ keV for NGC 2110. A fit with a thermal Comptonisation model yields a coronal temperature of $80^{+45}_{-20}$ keV and $75^{+20}_{-15}$ keV, respectively, and an optical depth of approximately two, assuming a spherical geometry. The coronal temperature and luminosity of both sources are consistent with pair production that acts as a thermostat for the thermal plasma. These results emphasise the importance of good signal-to-noise X-ray data above 100 keV to probe the high-energy emission of AGNs.