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Sgr A* represents a unique laboratory for the detailed study of accretionprocesses around a low-luminosity supermassive black hole (SMBH). Recent X-rayobservations have allowed for spatially resolved modeling of the emission fromthe accretion flow around the SMBH, placing tight constraints on the flux andspectral shape of the accretion from the inner region with $r<10^3~r_g$, where$r_g$ is the gravitational radius of the black hole. We present here the firstmodeling of the multi-band spectral energy distribution (SED) of this innerregion to better constrain the physical condition of the innermost accretionflow. Our modeling uses the Markov chain Monte Carlo (MCMC) method to fit theSED, accounting for the limitations on the accretion rate at the outer radiusof $10^3~r_g$ from the earlier works and the domination of the accretion flowwithin $30~r_g$ to the sub-mm bump. It is found that the fitting results of theoutflow index could be very different. If only the most luminous part of theSED, the sub-mm bump, is considered, the outflow index is about 0, while iflow-frequency radio data and X-ray data are also included, the outflow indexcould be 0.37 or even higher. The great difference of the fitting resultsindicates that the outflow index should be variable along radius, with a strongoutflow in the outer region and a weak outflow in the innermost region. Suchweak outflow agrees with numerical simulations and is possible to explain themulti-band SED even better.

Spectral Energy Distribution of the inner accretion flow around Sgr A* -- Clue for a weak outflow in the innermost region