Rc. Hartman et al., SIMULTANEOUS MULTIWAVELENGTH SPECTRUM AND VARIABILITY OF 3C-279 FROM 10(9) TO 10(24) HZ, The Astrophysical journal, 461(2), 1996, pp. 698-712
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 gamma-ray flare observed by EGRET in 1
991 June. A much less complete spectrum is presented for 1991 October.
Light curves from early 1991 to mid-1992 are presented for radio, mil
limeter, submillimeter, infrared, optical, and gamma-rays. Although th
e temporal coverage is incomplete, the only evidence for correlation i
n variability between the gamma-rays and lower frequencies is a flare
in the optical R-band that peaks within similar to 1 day of the maximu
m in the gamma-ray light curve. The variability shows higher relative
amplitude in gamma-rays than in the R band. We present spectral fits t
o the overall multi-wave band spectrum averaged over the 1991 June fla
re corresponding to two models: (i) synchrotron self-Compton (SSC) emi
ssion from a relativistic jet and (ii) inverse Compton scattering of s
eed photons originating external to the jet (ECS) by the synchrotron-e
mitting relativistic electrons in the jet. Either model can fit the ob
served spectra satisfactorily. The higher amplitude of the gamma-ray v
ariations is as predicted by the SSC model and can be accommodated wit
hin the ECS model if the flare is caused by a temporary change in the
bulk Lorentz factor of the gamma-ray-emitting plasma.