Simultaneous Multiwavelength Spectrum and Variability of 3C 279 from 10 9 to 10 24 Hz
Dermer, C. D.; Tornikoski, M.; Hermsen, W.; Aller, H. D.; Aller, M. F.; Smith, A. G.; Balonek, T. J.; Marscher, A. P.; Fujimoto, R.; Bennett, K.; Turner, M. J. L.; Makino, F.; Ohashi, T.; Hartman, R. C.; Webb, J. R.; Kii, T.; Sadun, A.; Mattox, J. R.; von Montigny, C.; Ryan, J.; Schoenfelder, V.; Hughes, P.; Teraesranta, H.; Travis, J. P.; Bloom, S. D.; Jenkins, P.; Kurfess, J. D.; Robson, I.
Abstract
Data from a number of monitoring programs have been combined with data from the Compton Gamma Ray Observatory and the Ginga X-ray satellite to construct a spectrum covering nearly 15 decades in frequency during or near the time of the 3C 279 γ-ray flare observed by EGRET in 1991 June. A much less complete spectrum is presented for 1991 October. Light curves from early 1991 to mid-1992 are presented for radio, millimeter, submillimeter, infrared, optical, and γ-rays. Although the temporal coverage is incomplete, the only evidence for correlation in variability between the γ-rays and lower frequencies is a flare in the optical R-band that peaks within ~1 day of the maximum in the γ-ray light curve. The variability shows higher relative amplitude in γ-rays than in the R band. We present spectral fits to the overall multi-wave band spectrum averaged over the 1991 June flare corresponding to two models: (i) synchrotron self-Compton (SSC) emission from a relativistic jet and (ii) inverse Compton scattering of seed photons originating external to the jet (ECS) by the synchrotron-emitting relativistic electrons in the jet. Either model can fit the observed spectra satisfactorily. The higher amplitude of the γ-ray variations is as predicted by the SSC model and can be accommodated within the ECS model if the flare is caused by a temporary change in the bulk Lorentz factor of the γ-ray-emitting plasma.