1995A&A...296..651T

We investigate the positive correlation between the X-ray flux in the 2-10keV band and the spectral index in the same spectral band observed in some Seyfert 1 galaxies. We propose that inverse Compton scattering of UV thermal photons by a population of non thermal relativistic electrons be the origin of this emisssion. Both the thermal UV emission and the Compton reprocessing take place inside the same plasma cloud. The cloud thermodynamical parameters as well as the properties of the relativistic electron distribution are selfconsistently derived in terms of the experimental data (UV luminosity, flux, spectral index and timescale variability in the X-ray domain). The observed trend between the flux and the spectral index is well reproduced if the number of relativistic electrons efficient in the inverse Compton scattering is constant and if the cloud temperature is of the order of 3x10⁵K.