Introduction

Though widely observed to be emanating out from a variety of galactic and extra-galactic sources, the underlying physical mechanism behind the formation of the Active Galactic Nuclei (AGN) and micro-quasar jets and outflows are enshrouded by the veil of mystery till date. One of the most prominent signatures of activities around the AGN is the presence of mass outflows and jets. AGNs produce cosmic jets through which immense amount of matter and energy are ejected out of the cores of the galaxies. Similarly, micro quasars have also been discovered where the mass outflow is formed from stellar mass black hole candidates. Possibly the sources of $\gamma$ ray bursts (GRB) also suffer mass loss through jets and outflows. Much work has been done on how such jets interact with their surrounding and on how such interactions may convey the informations about the morphology of different Galactic and extra galactic sources. However, the detailed nature of the formation of such jets is not quite clear due to the lack of proper understanding of the underlying physical mechanism responsible for jet production. Neither the amount of matter contained in these jets/outflows could accurately be calculated by any definitive method.

From the theoretical front, the non stellar activities around the above mentioned jet/outflow sources are thought to be produced by a powerful engine, an accreting astrophysical black hole, sitting at their dynamical centres. In this regard, it is also to be noted that since black holes do not have their own `physical' atmosphere to contribute outgoing material, jet/outflow for these candidates has to be generated from the accreting material only. Hence, it is quite logical to conclude that the jet formation from the above mentioned galactic and extra galactic sources, and accretion onto their central black holes are not two different issues to be studied disjointedly, rather they must be strongly correlated and it is necessary to study the accretion and jet within the same framework.