X-ray spectrum (0.1-10 keV) of the broad line radio galaxy - 3C 390.3

Abstract

Results are presented of observations of the broad-line radio galaxy, 3C 390.3 that were made with Exosat on several occasions between 1984 and 1986 using low- (LE) and medium-energy (ME) detectors. Detailed findings of the analysis of the LE and ME spectra of this source which were obtained from the Esoxat archives are adduced. A simple power-law and uniform-absorption model provided a good fit to the combined LE and ME spectra but the hydrogen column density (NH) values are much smaller than the galactic NH value. The observed X-ray spectrum is best fit by a power law of a photon index of 1.63 + or - 0.07. Only the 2-10 keV flux shows a weak change (about 25 percent) over a year, and practically no changes were observed in the LE flux. A highly significant (above 99.9 percent) Gaussian line feature around 5.80 keV was detected which could be redshifted 6.4 keV due to the fluorescence of cold iron from an optically thick accretion disk around the central nonthermal X-ray source.