Suzaku And Multi-Wavelength Observations of OJ 287 During the Periodic Optical Outburst in 2007

Journal Article · Thu Dec 01 04:00:00 EST 2011 · arXiv:0906.0234

OSTI ID:1030530

Seta, Hiromi; Isobe, N; Tashiro, Makoto S; Yaji, Yuichi; Arai, Akira; Fukuhara, Masayuki; Kohno, Kotaro; Nakanishi, Koichiro; Sasada, Mahito; Shimajiri, Yoshito; Tosaki, Tomoka; Uemura, Makoto; Anderhub, Hans; Antonelli, L A; Antoranz, Pedro; Backes, Michael; Baixeras, Carmen; Balestra, Silvia; Barrio, Juan Abel; Bastieri, Denis ; Becerra Gonzalez, Josefa

Suzaku observations of the blazar OJ 287 were performed in 2007 April 10-13 and November 7-9. They correspond to a quiescent and a flaring state, respectively. The X-ray spectra of the source can be well described with single power-law models in both exposures. The derived X-ray photon index and the flux density at 1 keV were found to be {Lambda} = 1.65 {+-} 0.02 and S{sub 1keV} = 215 {+-} 5 nJy, in the quiescent state. In the flaring state, the source exhibited a harder X-ray spectrum ({Lambda} = 1.50 {+-} 0.01) with a nearly doubled X-ray flux density S{sub 1keV} = 404{sub -5}{sup +6} nJy. Moreover, significant hard X-ray signals were detected up to {approx} 27 keV. In cooperation with the Suzaku, simultaneous radio, optical, and very-high-energy {gamma}-ray observations of OJ 287 were performed with the Nobeyama Millimeter Array, the KANATA telescope, and the MAGIC telescope, respectively. The radio and optical fluxes in the flaring state (3.04 {+-} 0.46 Jy and 8.93 {+-} 0.05 mJy at 86.75 Hz and in the V-band, respectively) were found to be higher by a factor of 2-3 than those in the quiescent state (1.73 {+-} 0.26 Jy and 3.03 {+-} 0.01 mJy at 86.75 Hz and in the V-band, respectively). No notable {gamma}-ray events were detected in either observation. The spectral energy distribution of OJ 287 indicated that the X-ray spectrum was dominated by inverse Compton radiation in both observations, while synchrotron radiation exhibited a spectral cutoff around the optical frequency. Furthermore, no significant difference in the synchrotron cutoff frequency was found between the quiescent and flaring states. According to a simple synchrotron self-Compton model, the change of the spectral energy distribution is 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.

• Research Organization: SLAC National Accelerator Laboratory (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 1030530
• Report Number(s): SLAC-PUB-14816; arXiv:0906.0234
• Journal Information: arXiv:0906.0234, Journal Name: arXiv:0906.0234 Journal Issue: 5 Vol. 61
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
Astrophysics
ASTRO
BL LACERTAE OBJECTS
ELECTRONS
ENERGY DENSITY
ENERGY SPECTRA
FLARING
FLUX DENSITY
GALAXIES
MAGNETIC FIELDS
PHOTONS
RADIATIONS
SYNCHROTRON RADIATION
SYNCHROTRONS
X-RAY SPECTRA