The Galactic Center radio jet

TL;DR

This paper models the radio emission of the Galactic Center's Sgr A* with a jet-disk system, confirming accretion rates and explaining observed emissions through a Blandford & K"onigl jet model.

Contribution

It introduces a jet-disk model for Sgr A* that aligns with observations and confirms a lower limit on accretion rate, providing insights into the energetics of the system.

Findings

Jet power is comparable to disk luminosity.

Model explains submm excess and IR emission absence.

Confirms lower limit of accretion rate  > 10^-8.5 M_sun.

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>>>