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

Abstract

Aims: We aim to measure the physical properties of the hot X-ray corona of two active galactic nuclei, NGC 4388 and NGC 2110.
Methods: We analysed the hard X-ray (20-300 keV) INTEGRAL spectrum in conjunction with archival XMM-Newton and NuSTAR data.
Results: 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_-40⁺⁷⁵ keV for NGC 4388 and 320_-60⁺¹⁰⁰ keV for NGC 2110. A fit with a thermal Comptonisation model yields a coronal temperature of 80_-20⁺⁴⁰ keV and 75_-15⁺²⁰ 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.

The reduced spectra (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/629/A54