2018/10/25 by Sean M. Ressler, Eliot Quataert, James M. Stone · 18 citations
Physics and Astronomy · #Accretion (finance) #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Black hole (networking) #Galactic Center #Magnetar #Physics #Pulsar #Pulsars and Gravitational Waves Research #Stars #astro-ph.HE
paper · pdf · doi:10.1093/mnrasl/sly201
published in Monthly Notices of the Royal Astronomical Society Letters 482(1), L123-L128 (Oxford University Press) · Accepted into MNRAS Letters. Comments welcome
openalex publication_date 2018/10/25 · arxiv created 2018/11/22 · arxiv updated 2018/11/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT 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.