The Galactic Center radio jet

Abstract

Recent observations of the radio and NIR source Sgr A* reinforce the interpretation of the Galactic Center as a scaled down version of an AGN. The discovery of an elongated structure at 43 GHz and increasing evidence for the presence of an accretion disk surrounding a Black Hole lead us to assume that both, an accretion disk and a jet, are present in the Galactic Center and are physically linked. We model the radio emission of Sgr A* successfully with a Blandford & K"onigl type jet and analyze the energetics of the coupled jet-disk system in Sgr A* where jet and disk are parametrized in terms of the accretion power. With this method we are able to confirm independently the lower limit of the Sgr A* accretion rate \dot M >> 10^-8.5 M_sun found previously. Moreover, using the limits imposed by observational data, we show that within such a jet-disk model, the total jet power Q_jet is of comparable order as the radiated disk luminosity L_disk. A jet model together with the assumption of an 10^6 M_sun Black Hole also qualitatively explains the submm excess and the lack of non-thermal IR radiation. The small size of the visible part of the jet (< 1 mas) is due to the low accretion rate of Sgr A*. <<<A&A Letters, in press>>>