Suzaku and multi-wavelength observations of a super massive binary black hole candidate, OJ 287

摘要

Suzaku observations of the blazar OJ 287 were performed in a quiescent and a flaring state in 2007. The X-ray spectra of the source were well described with single power-law models in both exposures. In the flaring state, the spectrum was harder with significant hard X-ray signals were detected up to ~ 27 keV, and the X-ray flux density was a factor of two higher, compared with that of the quiescent state. In cooperation with the Suzaku, simultaneous radio, optical, and very-high-energy 7-ray observations were performed with the Nobeyama Millimeter Array, the KANATA telescope, and the MAGIC telescope, respectively. The obtained spectral energy distribution of OJ 287 indicated that the X-ray spectrum was dominated by inverse Compton radiation in both observations, while the synchrotron component exhibited a spectral cutoff around the optical frequency. According to a simple synchrotron self-Compton model, it is estimated that the change of the spectral energy distribution was due to an increase in the energy density of electrons with small changes of both the magnetic field strength and the maximum Lorentz factor of electrons.