The active galaxy PKS 0208-512, detected at lower energies by COMPTEL, has been claimed to be a MeV blazar from EGRET. We report on the most recent INTEGRAL observations of the blazar PKS 0208-512, which are supplemented by Swift ToO observations. Th
e high energy X-ray and gamma-ray emission of PKS 0208-512 during August - December 2008 has been studied using 682 ks of INTEGRAL guest observer time and ~ 56 ks of Swift/XRT observations. These data were collected during the decay of a gamma-ray flare observed by Fermi/LAT. At X-ray energies (0.2 - 10 keV) PKS 0208-512 is significantly detected by Swift/XRT, showing a power-law spectrum with a photon index of ~ 1.64. Its X-ray luminosity varied by roughly 30% during one month. At hard X-/soft gamma-ray energies PKS 0208-512 shows a marginally significant (~ 3.2 sigma) emission in the 0.5-1 MeV band when combining all INTEGRAL/SPI data. Non-detections at energies below and above this band by INTEGRAL/SPI may indicate intrinsic excess emission. If this possible excess is produced by the blazar, one possible explanation could be that its jet consists of an abundant electron-positron plasma, which may lead to the emission of an annihilation radiation feature. Assuming this scenario, we estimate physical parameters of the jet of PKS 0208-512.
We report on an analysis of X- and $gamma$-ray observations of PKS 1830-211, based on the long-term campaigns carried out by emph{INTEGRAL} and COMPTEL. The emph{INTEGRAL} data currently available present a $33sigma$ significance detection in the 20-
100 keV band, while the COMPTEL 6-years data provide a $5.2sigma$ significance detection in the 1-3 MeV energy band. At hard X-rays, emph{INTEGRAL} and supplementary emph{SWIFT} observations show flux variability on timescales of months. At $gamma$-rays, the source shows persistent emission over years. The hard X-ray spectrum is well represented by a power-law model, with $Gamma sim 1.3$ in the 20-250 keV band. This photon index is well consistent with the previous report of $Gamma sim 1.3$ obtained at $E > 3.5$ keV from the best fit of emph{XMM-Newton} data with a broken power law model. The joint emph{XMM-Newton}/emph{INTEGRAL} spectrum presented here is then fit with a broken power-law model and the parameters are refined compared to the previous. The results show the photon index changes from $sim 1.0$ to $sim 1.3$ at a break energy $sim 4$ keV. At MeV energies, the spectrum softens to $Gamma sim 2.2$. These results, together with the EGRET measurement at $E ge 100$ MeV, constitute a broad-band spectrum containing the peak of the power output at MeV energies, similar to most high-luminosity $gamma$-ray blazars. The measured spectral characterstics are then discussed in the framework of the gravitational lens effects.
