The disc-jet symbiosis emerges: Modelling the emission of Sagittarius A* with electron thermodynamics

S. M. Ressler, A. Tchekhovskoy, E. Quataert, C. F. Gammie

Research output: Contribution to journalArticlepeer-review

105 Scopus citations


We calculate the radiative properties of Sagittarius A* - spectral energy distribution, variability and radio-infrared images - using the first 3D, physically motivated black hole accretion models that directly evolve the electron thermodynamics in general relativistic MHD simulations. These models reproduce the coupled disc-jet structure for the emission favoured by previous phenomenological analytic and numerical works. More specifically, we find that the low frequency radio emission is dominated by emission from a polar outflow while the emission above 100 GHz is dominated by the inner region of the accretion disc. The latter produces time variable near-infrared (NIR) and X-ray emission, with frequent flaring events (including IR flares without corresponding X-ray flares and IR flares with weak X-ray flares). The photon ring is clearly visible at 230 GHz and 2 μm, which is encouraging for future horizon-scale observations. We also show that anisotropic electron thermal conduction along magnetic field lines has a negligible effect on the radiative properties of our model. We conclude by noting limitations of our current generation of first-principles models, particularly that the outflow is closer to adiabatic than isothermal and thus underpredicts the low frequency radio emission.

Original languageEnglish (US)
Pages (from-to)3604-3619
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Jun 1 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Accretion
  • Accretion discs
  • Black hole physics
  • Galaxy: centre
  • MHD
  • Relativistic processes


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