X-ray data above 100 keV to probe the high-energy emission of AGNs. ]{}

Introduction
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One of the main components of active galactic nuclei (AGNs) is a hot corona, which is thought to produce the X-ray emission via thermal Comptonisation of optical and UV photons from the accretion disc. This process naturally explains the observed power-law shape of the X-ray spectra of AGNs and their high-energy cut-off, which is related to the coronal temperature. The cut-off has often been observed at $\sim 100$ keV thanks to both past and current X-ray missions, such as the *Compton Gamma-Ray Observatory*’s Oriented Scintillation Spectrometer Experiment [OSSE; @zdziarski2000], [[*BeppoSAX*]{}]{} [@perola2002], [[*Swift*]{}]{}’s Burst Alert Telescope [BAT; @bat70; @ricci2017], [[*INTEGRAL*]{}]{} [@malizia2014], and [[*NuSTAR*]{}]{} [@fabian2015; @tortosa2018 and references therein]. Good constraints on the high-energy cut-off have been, and are still, obtained for a number of AGNs with [[*NuSTAR*]{}]{}. This leads to measurements of the coronal temperature to range from 15–20 keV in the ‘coolest’ sources [@kara2017; @tortosa2017; @buisson2018; @turner2018] to $\sim 400$ keV in NGC 5506 [@matt20155506]. However, in many cases only lower limits to the cut-off have been reported [e.g. @kamraj2018] that can still be useful to constrain the geometrical and physical parameters of the hot 