Constraints on Jet-driven Disk Accretion in Sagittarius A

We revisit theoretical and observational constraints on geometrically thin disk accretion in Sagittarius A* (Sgr A*). We show that the combined effects of mass outflows and electron energization in the hot part of the accretion flow can deflate the inflowing gas from a geometrically thick structure. This allows the gas to cool and even thermalize on an inflow timescale. As a result, a compact, relatively cool disk may form at small radii. We show that magnetic coupling between the relativistic disk and a steady state jet results in a disk that is less luminous than a standard relativistic disk accreting at the same rate. This relaxes the observational constraints on thin-disk accretion in Sgr A* (and by implication, other low- luminosity active galactic nuclei [LLAGNs]). We find typical cold gas accretion rates of [image] M sub([image]) yr super(-1). We also find that the predicted modified disk emission is compatible with existing near-infrared (NIR) observations of Sgr A* in its quiescent state, provided that the disk inclination angle is [image]87 degree and that the jet extracts more than 75% of the accretion power.