Quenched radio emission in cygnus X-3

Flux density measurements for the x-ray binary Cygnus X-3 obtained at 15 GHz with the Ryle Telescope during 1994-1995 are compared with flux densities at 2.25 and 8.3 GHz obtained with the NRL-Green Bank Interferometer. The Ryle Telescope measured lower quenched radio flux densities at 15 GHz than those reported at 2.25 and 8.3 GHz prior to the 1994 February outburst. The time scales observed for the delay of small flare peak flux densities at lower frequencies sets limits on opacity in a spherically-symmetric stellar wind. The upper-limit for the mass-loss rate (Ṁ∼1.0×10-5 M⊙/yr) is close to the dynamical mass-loss rate for a 10 M⊙ Wolf-Rayet star and 1.4 M⊙ compact companion. A higher mass-loss rate (Ṁ≳2.0×10-5 M⊙/yr) may occur either if the wind is very hot (3.5×105 K), or if it is cool (≤10,000 K) and partially ionized. Time scales observed for the onset of quenched radio emission support a model in which particle injection into the radio jet is suppressed. © 1996 American Astronomical Society.