ASCA observations of blazars and multiband analysis

We present multiband data for 18 blazars observed with ASCA, half of which were also observed contemporaneously with EGRET as parts of multi-wavelengt h campaigns. The ASCA X-ray spectra of High-energy peaked BL Lacs (HBLs) ar e soft, and they form the highest energy tail of the low energy (synchrotro n) component. The X-ray spectra of the quasar-hosted blazars (QHBs) are har d and consistent with the lowest energy end of the high energy (HE, Compton ) component. For Low-energy peaked BL Lacs (LBLs), the X-ray spectra are in termediate. We find that the radiation process responsible for the HE peak for HBLs can be explained solely by Synchrotron-Self-Compton (SSC) emission . For many QHBs, on the other hand, the gamma-rays cannot be solely due to the SSC mechanism. We consider an alternative scenario for QHBs where the S SC component dominates in the X-ray band, but it is below the observed gamm a-ray spectrum. We infer the magnetic field to be 0.1 - 1 Gauss, and Lorent z factors of electrons radiating at the peak of the vF(v) spectrum of 10(3) for QHBs. This is much lower than 10(5) for HBLs. This difference is most likely due to the large photon density expected in QHBs.