MEASURING mass accretion rate onto the supermassive black hole in M87 using faraday rotation measure with the submillimeter array

C. Y. Kuo, K. Asada, R. Rao, M. Nakamura, J. C. Algaba, H. B. Liu, M. Inoue, P. M. Koch, P. T.P. Ho, S. Matsushita, H. Y. Pu, K. Akiyama, H. Nishioka, N. Pradel

Research output: Contribution to journalArticlepeer-review

78 Citations (Scopus)

Abstract

We present the first constraint on the Faraday rotation measure (RM) at submillimeter wavelengths for the nucleus of M87. By fitting the polarization position angles (χ) observed with the Submillimeter Array at four independent frequencies around 230 GHz and interpreting the change in χ as a result of external Faraday rotation associated with accretion flow, we determine the RM of the M87 core to be between -7.5 × 105 and 3.4 × 105 rad m-2. Assuming a density profile of the accretion flow that follows a power-law distribution and a magnetic field that is ordered, radial, and has equipartition strength, the limit on the RM constrains the mass accretion rate to be below 9.2 10-4 M yr-1 at a distance of 21 Schwarzschild radii from the central black hole. This value is at least two orders of magnitude smaller than the Bondi accretion rate, suggesting significant suppression of the accretion rate in the inner region of the accretion flow. Consequently, our result disfavors the classical advection-dominated accretion flow and prefers the adiabatic inflow-outflow solution or convection-dominated accretion flow for the hot accretion flow in M87.

Original languageEnglish
Article numberL33
JournalAstrophysical Journal Letters
Volume783
Issue number2
DOIs
Publication statusPublished - 2014 Mar 10
Externally publishedYes

Keywords

  • accretion, accretion disks galaxies
  • active galaxies
  • individual (M87) - galaxies
  • nuclei - polarization

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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