Low angular momentum flow model for Sgr A*

Abstract

We examine the low angular momentum flow model for Sgr A* using two-dimensional hydrodynamical calculations based on the parameters of the specific angular momentum and total energy estimated in the recent analysis of stellar wind of nearby stars around Sgr A*. The accretion flow with the plausible parameters is non-stationary and an irregularly oscillating shock is formed in the inner region of a few tens to a hundred and sixty Schwarzschild radii. Due to the oscillating shock, the luminosity and the mass-outflow rate are modulated by several per cent to a factor of 5 and a factor of 2-7, respectively, on time-scales of an hour to ten days. The flows are highly advected and the radiative efficiency of the accreting matter into radiation is very low, 10^{-5}--$10^{-3}, and the input accretion rate of 4.0* 10^{-6} solar mass/yr results in the observed luminosities -- 10^{36} erg/s of Sgr A* if a two-temperature model and the synchrotron emission are taken into account. The mass-outflow rate of the gas originating in the post-shock region increases with the increasing input specific angular momentum and ranges from a few to 99 per cent of the input accreting matter, depending on the input angular momentum. The oscillating shock is necessarily triggered if the specific angular momentum and the specific energy belong to or are located just nearby in the range of parameters responsible for a stationary shock in rotating inviscid and adiabatic accretion flow. The time variability may be relevant to the flare activity of Sgr A*.

11 pages, 13 figures

References in corpus (10)

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• A 600 minute near-infrared lightcurve of Sagittarius A*
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Cited by in corpus (11)

• Oscillating shocks in the low angular momentum flows as a source of variability of accreting black holes
• Unstable mass-outflows in geometrically thick accretion flows around black holes
• A Possible Model for the Long-Term Flares of Sgr A*
• Gamma-ray emission from proton-proton interactions in hot accretion flows
• Perturbation of mass accretion rate, associated acoustic geometry and stability analysis
• Low angular momentum flow model II for Sgr A*
• Black Hole spin dependence of general relativistic multi-transonic accretion close to the horizon
• Radiative shock oscillation model for the long-term flares of Sgr A*
• Effect of matter geometry on low angular momentum black hole accretion in the Kerr metric
• Influence of flow thickness on general relativistic low angular momentum accretion around spinning black holes
• A two-fluid model for black-hole accretion flows: Particle acceleration, outflows, and TeV emission