SIMBAD references

2019MNRAS.482L.123R - Mon. Not. R. Astron. Soc., 482, L123-L128 (2019/January-1)

Accretion of magnetized stellar winds in the Galactic centre: implications for Sgr A* and PSR J1745-2900.


Abstract (from CDS):

The observed rotation measures (RMs) towards the Galactic centre magnetar and towards Sagittarius A* provide a strong constraint on MHD models of the Galactic centre accretion flow, probing distances from the black hole separated by many orders of magnitude. We show, using three-dimensional simulations of accretion via magnetized stellar winds of the Wolf-Rayet stars orbiting the black hole, that the large, time-variable RM observed for the pulsar PSR J1745-2900 can be explained by magnetized wind-wind shocks of nearby stars in the clockwise stellar disc. In the same simulation, both the total X-ray luminosity integrated over 2-10 arcsec, the time variability of the magnetar's dispersion measure, and the RM towards Sagittarius A* are consistent with observations. We argue that (in order for the large RM of the pulsar to not be a priori unlikely) the pulsar should be on an orbit that keeps it near the clockwise disc of stars. We present a two-dimensional RM map of the central 1/2 parsec of the Galactic centre that can be used to test our models. Our simulations predict that Sgr A* is typically accreting a significantly ordered magnetic field that ultimately could result in a strongly magnetized flow with flux threading the horizon at ∼10 per cent of the magnetically arrested limit.

Abstract Copyright: © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): accretion, accretion discs - black hole physics - (magnetohydrodynamics) MHD - polarization - stars: Wolf-Rayet - Galaxy: centre

Simbad objects: 9

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