ABSTRACT

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ABSTRACT: We investigate various models of accretion disks for Sgr A*, the most puzzling region of our Galaxy. The generic image we have taken into account consists of a black hole, an accretion disk and a jet. There are various accretion models to explain the low NIR flux of Sgr A* : a standard accretion disk with a jet, an ADAF, or an EDAF model. We find that all of these models are conceptually similar. The accretion model which allows the formation of the jet at the innermost edge of the disk requires a subkeplerian gas motion and a very large base of the jet. The large base of the jet may be unrealistic for Sgr A*, since the jet model and the observations suggest that the jet is collimated and anchored in the disk in a very narrow region of the disk close to the black hole. Nevertheless a large fraction of the energy is taken up by the jet while the remaining energy, which is not converted into radiation, goes directly to the black hole through an advection dominated flow or can escape through an EDAF flow outwards.