Swift/XRT–NuSTAR Spectra of Type 1 AGN: Confirmingintegralresults on the High-Energy Cut-off

We present the 0.5 - 78 keV spectral analysis of 18 broad line AGN belongingto the INTEGRAL complete sample. Using simultaneous Swift-XRT and NuSTARobservations and employing a simple phenomenological model to fit the data, wemeasure with a good constraint the high energy cut-off in 13 sources, while weplace lower limits on 5 objects. We found a mean high-energy cut-off of 111 keV(standard deviation = 45 keV) for the whole sample, in perfect agreement withwhat found in our previous work using non simultaneous observations and withwhat recently published using NuSTAR data. This work suggests that simultaneityof the observations in the soft and hard X-ray band is important but not alwaysessential, especially if flux and spectral variability are properly accountedfor. A lesser agreement is found when we compare our cut-off measurements withthe ones obtained by Ricci et al. (2017) using Swift-BAT high energy data,finding that their values are systematically higher than ours. We haveinvestigated whether a linear correlation exists between photon index and thecut-off and found a weak one, probably to be ascribed to the non perfectmodelling of the soft part of the spectra, due to the poor statistical qualityof the 2-10 keV X-ray data. No correlation is also found between the Eddingtonratio and the cut-off, suggesting that only using high statistical qualitybroad-band spectra is it possible to verify the theoretical predictions andstudy the physical characteristics of the hot corona and its geometry.