Showing papers by "Mark J. Reid published in 1984"

Low-level radio flares from Cygnus X-3

Abstract: Cygnus X-3 is a poorly understood but interesting galactic X-ray source. It is unusual in that it shows variable low-state (Sv<1 Jy) radio emission1 as well as spectacular radio flares (Sv∼20 Jy). The spectacular flares have long been interpreted as synchrotron emission from an expanding source2; more recent work3 implies that Cyg X-3 may be one of the few identified radio jets in the Galaxy. Flux-density variations with a period of 4.8 h have been discovered at X-ray4 and IR5 wavelengths, and possibly at γ-ray energies6,7 from 108 eV to 1016 eV. The X-ray emission is probably produced in a binary system composed of a low-mass star orbiting a compact object with an accretion disk and an accretion disk corona8. As interstellar absorption9 (Av = 19) precludes study of the optical emission, the applicability of this model to Cyg X-3 rests heavily on analogy with other sources with similar X-ray properties (such as, 4U1822-37 and 4U2129+47). We report here observations with the Very Large Array (VLA) of Cyg X-3 at several radio wavelengths which show that the radio emission in its low state may be interpreted as arising entirely from the superposition of a series of flares that are wavelength dependent with an apparent period near the 4.8-h X-ray period10. A model of the source, in which each flare represents the injection of relativistic particles into a small volume which subsequently expands at constant velocity, is qualitatively consistent with the data.