Relativistic superluminal radio jets in microquasars in our galaxy
  We discuss the origin of superluminal radio jets in Black hole X-ray binaries with relativistic radio jets in our Galaxy popularly known as microquasars. We classify the relativistic superluminal jet according to the radio emission in black hole X-ray binaries (transient or persistent) rather than the mass of the companion. The black hole X-ray binaries with transient radio emission (mostly LMXBs) produce superluminal jets with $\beta_{app} >$ 1 when the accretion rate, $\dot{m}_{accr}$ is high and the bolometric luminosity L$_{bol}$ approaches the Eddington Luminosity, L$_{Edd}$. On the other hand, the black hole X-ray binaries with persistent radio emission (mostly HMXBs) produce superluminal jets with $\beta_{app} <$ 1 at relatively low $\dot{m}_{accr}$. We specially discuss the case of V4641 Sgr, a HMXB with transient radio emission which produces superluminal radio jets like in LMXBs. 
J S Yadav