GRS 1915+105: the flux ratio of twin radio clouds as a measure of asymmetry between counter jets

Abstract

Resolution of both approaching and receding ejecta in the galactic microquasars makes possible to measure the flux ratio S_a/S_r of the twin ejecta, which contains an important information about the nature of the jets. We show that the flux ratio observed from GRS 1915+105 during the prominent March/April 1994 radio flare can be explained in terms of relativistic motion of discrete radio clouds, if one assumes that the twin ejecta are similar, but not completely identical, i.e. allowing for some asymmetry between the plasmoids in their speeds of propagation and/or luminosities. The recoil momentum due to asymmetrical ejection of the pair of plasmoids could be comparable with the momentum accumulated in the inner accretion disk. We suggest a possible explanation of the observed anticorrelation between the X-ray and radio flares as the result of drastic structural changes in the inner disk caused by production of powerful jets. The delay between the times of decline of X-rays and appearance of strong radio flares is explained as the time needed for expansion of radio clouds to become optically thin.