DOI:
10.3847/0004-637X/819/1/60
Authors:
Yusef-Zadeh, F.; Wardle, M.; Schoedel, R.; Roberts, D. A.; Cotton, W.; Bushouse, H.; Arendt, R.; Royster, M.
Abstract:
We present high-resolution multiwavelength radio continuum images of the region within 150 '' of Sgr. A*, revealing a number of new extended features and stellar sources in this region. First, we detect a continuous 2 '' east-west ridge of radio emission, linking Sgr. A* and a cluster of stars associated with IRS 13 N and IRS 13E. The ridge suggests that an outflow of east-west blob-like structures is emerging from Sgr. A*. In particular, we find arc-like radio structures within the ridge with morphologies suggestive of photoevaporative protoplanetary disks. We use infrared K-s and L' fluxes to show that the emission has similar characteristics to those of a protoplanetary disk irradiated by the intense radiation field at the Galactic center. This suggests that star formation has taken place within the S-cluster 2 ''. from Sgr. A*. We suggest that the diffuse X-ray emission associated with Sgr A* is due to an expanding hot wind produced by the mass loss from B-type main sequence stars, and/or the disks of photoevaporation of low mass young stellar objects (YSOs) at a rate of similar to 10(-6) M-circle dot yr(-1). The proposed model naturally reduces the inferred accretion rate and is an alternative to the inflow-outflow style models to explain the underluminous nature of Sgr A*. Second, on a scale of 5. from Sgr A*, we detect new cometary radio and infrared sources at a position angle PA similar to 50 degrees which is similar to that of two other cometary sources X3 and X7, all of which face Sgr A*. In addition, we detect a striking tower of radio emission at a PA similar to 50 degrees-60 degrees along the major axis of the Sgr A East supernova remnant shell on a scale of 150 '' from Sgr A*. We suggest that the cometary sources and the tower feature are tracing interaction sites of a mildly relativistic jet from Sgr A* with the atmosphere of stars and the nonthermal Sgr A East shell at a PA similar to 50 degrees-60 degrees with (M) over dot similar to 1 x 10(-7) M-circle dot yr(-1), and opening angle 10 degrees. Lastly, we suggest that the east-west ridge of radio emission traces an outflow that is potentially associated with past flaring activity from Sgr A*. The position angle of the outflow driven by flaring activity is close to -90 degrees.
URL:
https://ui.adsabs.harvard.edu/#abs/2016ApJ...819...60Y/abstract
Keywords:
accretion, accretion disks; black hole physics; Galaxy: center