What do we understand from multi-frequency monitoring of microquasars?

Abstract

We discuss the results of the monitoring programs of the X-ray binaries with relativistic jets studies. We carried out a multi-frequency (1-30 GHz) daily monitoring of the radio flux variability of the microquasars SS433, GRS1915+105, V4641 Sgr and Cyg X-3 with RATAN-600 radio telescope during the recent sets in 2002-2006. We detected a lot of bright short-time flares from GRS 1915+105 which could be associated with active X-ray events. In 2004 we have detected two flares from V4641 Sgr, which followed after recurrent X-ray activity of the transient. From September 2005 to May 2006 and then in July we have daily measured flux densities from Cyg X-3. In January 2006 we detected a drop down of its quiescent fluxes (from 100 to ~20 mJy), then the 1Jy-flare was detected on 2 February 2006 after 18 days of quenched radio emission. The daily spectra of the flare in the maximum were flat from 2 to 110 GHz, using the quasi-simultaneous observations at 110 GHz with the RT45m telescope and the NMA millimeter array of the Nobeyama Radio Observatory in Japan. Several bright radio flaring events (1-15 Jy) followed during the continuing state of very variable and intensive 1-12 keV X-ray emission (~0.5 Crab), which was monitored in the RXTE ASM program. We discuss the various spectral and temporal characteristics of the light curves from the microquasars. Thus we conclude that monitoring of the flaring radio emission is a good tracer of jet activity X-ray binaries.