The 1993 Multiwavelength Campaign on 3C 279: The Radio to Gamma-Ray Energy Distribution in Low State
Maraschi, L.; Ghisellini, G.; Pian, E.; Glass, I. S.; Madejski, G. M.; Grandi, P.; Treves, A.; Stevens, J. A.; Koratkar, A. P.; Bailyn, C. D.; Wagner, S. J.; Urry, C. M.; Aller, H. D.; Aller, M. F.; Balonek, T. J.; Robson, E. I.; McHardy, I. M.; Thomas, H. C.; Hartman, R. C.; Wehrle, A. E.; Collmar, W.; Bock, H.; Fink, H. H.; von Montigny, C.; Litchfield, S. J.; Mendez, R.; Pesce, J.; Reuter, H. P.; Steppe, H.; Teraesranta, H.
Italy, United States
Abstract
Simultaneous observations of 3C 279 at radio, millimeter, near- infrared, optical, ultraviolet (with IUE) and X-ray (with ROSAT) wavelengths were obtained in 1992 December-1993 January, during a three week pointing at the source by the Compton Gamma Ray Observatory. The blazar was in a quiescent or "low" state during this period. Comparing the multiwavelenth energy distribution to that from 1991 June, when 3C 279 was in its brightest recorded γ-ray state, we find the following: 1. 3C 279 faded dramatically at all frequencies above 10^14^ Hz, while the flux variations at low frequencies (radio to millimeter wavelengths) were minor. 2. The near infrared optical ultraviolet spectral shape was softer (steeper) in the quiescent state, and the X-ray spectra also appear softer, although the spectral index measured by ROSAT refer to a lower energy band than that measured earlier with Ginga. 3. The ratio of the γ-ray luminosity to that across all other frequencies decreased from a value of ~10 in the flaring state to a value ~1 in the quiescent state. These findings imply that the production of γ-rays is closely related to the optical-ultraviolet continuum, in agreement with models where γ-rays are produced through inverse Compton (IC) scattering by relativistic electrons emitting the synchrotron continuum. The observed nonlinear relation between the synchrotron and IC requires both a change in the electron spectrum and an associated change in the seed photons.