Mon. Not. R. Astron. Soc., 487, 4355-4371 (2019/August-2)
Chandra reveals a possible ultrafast outflow in the super-Eddington Be/X-ray binary Swift J0243.6+6124.
VAN DEN EIJNDEN J., DEGENAAR N., SCHULZ N.S., NOWAK M.A., WIJNANDS R., RUSSELL T.D., HERNANDEZ SANTISTEBAN J.V., BAHRAMIAN A., MACCARONE T.J., KENNEA J.A. and HEINKE C.O.
Abstract (from CDS):
Accretion at super-Eddington rates is expected to be accompanied by strong outflows. Such outflows are observed in Galactic X-ray binaries and extragalactic ultraluminous X-ray sources (ULXs). However, due to their large source distances, ULX outflows are challenging to detect and study in detail. Galactic neutron stars accreting from a Be-star companion at super-Eddington rates show many similarities to ULX pulsars, and therefore offer an alternative approach to study outflows in this accretion regime. Here, we present Chandra high-resolution spectroscopy of such a super-Eddington accreting neutron star, Swift J0243.6+6124, to search for wind outflow signatures during the peak of its 2017/2018 giant outburst. We detect narrow emission features at rest from Ne, Mg, S, Si, and Fe. In addition, we detect a collection of absorption features which can be identified in two ways: either as all Fe transitions at rest (with a possible contribution from Mg), or a combination of three blue-shifted Ne and Mg lines at ∼0.22c, while the remaining lines are at rest. The second scenario would imply an outflow with a velocity similar to those seen in ULXs, including the ULX pulsar NGC 300 ULX-1. This result would also imply that Swift J0243.6+6124 launches both a jet, detected in radio and reported previously, and an ultrafast wind outflow simultaneously at super-Eddington accretion rates.
© The Author(s) 2019. Published by Oxford University Press on behalf of The Royal Astronomical Society.
accretion, accretion discs - stars: neutron - pulsars: individual: Swift J0243.6+6124 - X-rays: binaries
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