Constraints on the mass accretion rate onto the supermassive black hole of cygnus : A using the Submillimeter Array

• Main Authors: Lo, Wen-Ping, Asada, Keiichi, Matsushita, Satoki, Nakamura, Masanori, Pu, Hung-Yi, Tseng, Chihyin, Akiyama, Kazunori, Algaba, Juan Carlos, Bower, Geoffrey C., Rao, Ramprasad, Koay, Jun Yi, Koch, Patrick M., Koyama, Shoko, Ho, Paul T. P., Inoue, Makoto
• Format: Article
• Published: IOP Publishing Ltd 2021
• Subjects: QB Astronomy; QC Physics
• Online Access: http://eprints.um.edu.my/34637/

We present the first detailed polarimetric studies of Cygnus A at 230 GHz with the Submillimeter Array (SMA) to constrain the mass accretion rate onto its supermassive black hole. We detected the polarized emission associated with the core at a fractional polarization of 0.73 +/- 0.15%. This low fractional polarization suggests that the polarized emission is highly depolarized. One of the possible explanations is due to a significant variance in the Faraday rotation measure within the synthesized beam. By assuming the Faraday depolarization caused by inhomogeneous column density of the magnetized plasma associated with the surrounding radiatively-inefficient accretion flow within the SMA beam, we derived the constraint on the mass accretion rate to be larger than 0.15 M-circle dot yr(-1) at the Bondi radius. The derived constraint indicates that an adiabatic inflow-outflow solution or an advection-dominated accretion flow should be preferable as the accretion flow model in order to explain the jet power of Cygnus A.