Modelling the black hole silhouette in Sgr A* with ion tori

Abstract

We calculate the "observed at infinity" image and spectrum of the accretion structure in Sgr A*, by modelling it as an optically thin, constant angular momentum ion torus in hydrodynamic equilibrium. The physics we consider includes a two-temperature plasma, a toroidal magnetic field, as well as radiative cooling by bremsstrahlung, synchrotron and inverse Compton processes. Our relativistic model has the virtue of being fully analytic and very simple, depending only on eight tunable parameters: the black hole spin and the inclination of the spin axis to our line of sight, the torus angular momentum, the polytropic index, the magnetic to total pressure ratio, the central values of density and electron temperature and the ratio of electron to ion temperatures. The observed image and spectrum are calculated numerically using the ray-tracing code GYOTO. Our results demonstrate that the ion torus model is able to account for the main features of the accretion structure surrounding Sgr A*.

11 pages, 10 figures, submitted to A & A

References in corpus (6)

• Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre
• The Submillimeter Bump in Sgr A* from Relativistic MHD Simulations
• Polarimetry of near-infrared flares from Sagittarius A*
• Magnetized Tori around Kerr Black Holes: Analytic Solutions with a Toroidal Magnetic Field
• Time Dependent Models of Flares from Sagittarius A*
• Black Hole Shadow Image and Visibility Analysis of Sagittarius A*

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• 3+1 geodesic equation and images in numerical spacetimes
• A magnetized torus for modeling Sgr A* millimeter images and spectra
• Bremsstrahlung in GRMHD models of accreting black holes
• Multi-wavelength torus-jet model for Sgr~A*
• Axisymmetric, stationary collisionless gas configurations surrounding black holes
• Stationary models of magnetized viscous tori around a Schwarzschild black hole
• Equatorial orbits and imaging of hairy cubic Galileon black holes
• Studies on Thin-shells and Thin-shell Wormholes