ASCA observations of blazars and multiband analysis Original Research Article

We present data for 18 blazars observed with ASCA, half of which were also observed contemporaneously with EGRET as parts of multi-wavelength campaigns. the ASCA X-ray spectra of High-energy peaked BL Lacs (HBLs) are soft, and they form the highest energy tail of the low energy (synchrotron) component. The X-ray spectra of the quasar-hosted blazars (QHBs) are hard and consistent with the lowest energy end of the high energy (Compton) component. For Low-energy peaked BL Lacs (LBLs), the X-ray spectra are intermediate. 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 γ-rayscannot be solely due to the SSC mechanism. We consider an alternative scenario for QHBs where the SSC component dominates in the X-ray band, but it is below the observed γ-ray spectrum. We infer the magnetic field B to be 0.1 – 1 Gauss, and Lorentz factors γb of electrons radiating at the peak of the νF(ν) spectrum of ∼ 103 for QHBs. This is much lower than γb ∼ 10 5 for HBLs.