Multi-wavelength studies of the broad line radio galaxies IGR J21247+5058 and 3C 390.3

Abstract

We present a multi-wavelength study of two broad line radio galaxies: IGR J21247+5058, one of the brightest AGN discovered by INTEGRAL, and 3C 390.3, also extensively observed by INTEGRAL. All the available INTEGRAL, XMM-Newton and Swift data were analysed, covering the 0.3-200 keV range. The spectral energy distribution of IGR J21247+5058 was extracted from the total observed spectrum in the IR to UV bands, using a blackbody model to account for the emission of a star in the line of sight. The broad band X-ray spectrum of IGR J21247+5058 can be described by a cut-off (EC = 206 +180 −61 keV) power law (Gamma = 1.56+0.09 −0.07) plus a reflection component (R = 0.8+0.5 −0.4), absorbed by a double layer of partially covering neutral material. The X-ray spectrum of 3C 390.3 can be represented by an absorbed power law (NH ≃ 4.5e20 cm−2, Gamma = 1.78 +0.02 −0.02) plus a blackbody component (kT ≃ 150 eV). Both radio galaxies show weak K iron lines. The spectral energy distribution of IGR J21247+5058 shows the presence of two peaks, one in the near infrared and one in the X-rays. While the X-ray peak may be due to inverse Comptonisation of synchrotron photons, the one in the IR is likely due to thermal emission. The spectral energy distribution of 3C 390.3 shows two strong peaks in the IR and X-rays and a third peak in the UV, whose height varies considerably between XMM-Newton and Swift observations. The IR peak is interpreted as due to synchrotron emission, while the one in the UV as emission from the disk, and it does not seem to be related to the soft excess in the X-rays.