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