The 1993 multiwavelength campaign on 3C 279: the radio to gamma-ray energy distribution inlow state

L. Maraschi, P. Grandi, C.M. Urry, A. E. Wehrle, G.M. Madejski, H. Fink, G. Ghisellini, R.C. Hartman, A.P. Koratkar, C. von Montigny, E. Pian, H.C. Thomas, A. Treves, M. F. Aller, H. D. Aller, C. D. Bailyn, T.J. Balonek, H. Bock, W. Collmar, I.S. GlassS.J. Litchfield, I.M. McHardy, R. Mendez, J. Pesce, H.-P. Reuter, E.I. Robson, H. Steppe, Jason Stevens, H. Teraesranta, S.J. Wagner

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117 Citations (Scopus)

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 multiwavelength energy distribution to that from 1991 June, when 3C 279 was in its brightest recorded gamma-ray state, we find the following: (1) 3C 279 faded dramatically at all frequencies above 1014 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 gamma-ray luminosity to that across all other frequencies decreased from a value of approximately equal to 10 in the flaring state to a value approximately equal to 1 in the quiescent state. These findings imply that the production of gamma-rays is closely related to the optical-ultraviolet continuum, in agreement with models where gamma-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.

Original languageEnglish
Pages (from-to)L91-L95
JournalAstrophysical Journal Letters
Volume435
Issue number2
DOIs
Publication statusPublished - 1 Nov 1994

Keywords

  • ACTIVE GALAXIES, BLAZARS, ENERGY DISTRIBUTION, GAMMA RAYS, INFRARED RADIATION, MICROWAVES, QUASARS, RADIO WAVES, ULTRAVIOLET RADIATION, X RAYS, COMPTON EFFECT, GAMMA RAY OBSERVATORY, GAMMA RAY SPECTRA, GINGA SATELLITE, IUE, ROSAT MISSION, SATELLITE-BORNE INSTRUMENTS, SYNCHROTRONS

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