The University of Southampton
University of Southampton Institutional Repository
 ePrints Soton is experiencing an issue with some file downloads not being available. We are working hard to fix this. Please bear with us.

# Thermal and radiation driving can produce observable disk winds in hard-state X-ray binaries

Higginbottom, Nick, Knigge, Christian, Sim, Stuart A., Long, Knox S., Matthews, James H., Hewitt, Henrietta A., Parkinson, Edward J. and Mangham, Sam W. (2020) Thermal and radiation driving can produce observable disk winds in hard-state X-ray binaries. Monthly Notices of the Royal Astronomical Society, 492 (4), 5271-5279.

Record type: Article

## Abstract

X-ray signatures of outflowing gas have been detected in several accreting black-hole binaries, always in the soft state. A key question raised by these observations is whether these winds might also exist in the hard state. Here, we carry out the first full-frequency radiation hydrodynamic simulations of luminous ($\rm{L = 0.5 \, L_{\mathrm{Edd}}}$) black-hole X-ray binary systems in both the hard and the soft state, with realistic spectral energy distributions (SEDs). Our simulations are designed to describe X-ray transients near the peak of their outburst, just before and after the hard-to-soft state transition. At these luminosities, it is essential to include radiation driving, and we include not only electron scattering, but also photoelectric and line interactions. We find powerful outflows with $\rm{\dot{M}_{wind} \simeq 2 \,\dot{M}_{acc}}$ are driven by thermal and radiation pressure in both hard and soft states. The hard-state wind is significantly faster and carries approximately 20 times as much kinetic energy as the soft-state wind. However, in the hard state the wind is more ionized, and so weaker X-ray absorption lines are seen over a narrower range of viewing angles. Nevertheless, for inclinations $\gtrsim 80^{\circ}$, blue-shifted wind-formed Fe XXV and Fe XXVI features should be observable even in the hard state. Given that the data required to detect these lines currently exist for only a single system in a {\em luminous} hard state -- the peculiar GRS~1915+105 -- we urge the acquisition of new observations to test this prediction. The new generation of X-ray spectrometers should be able to resolve the velocity structure.

Text
2001.08547v2 - Accepted Manuscript

Accepted/In Press date: 20 January 2020
e-pub ahead of print date: 25 January 2020
Published date: March 2020
Keywords: astro-ph.HE, astro-ph.IM, astro-ph.SR

## Identifiers

Local EPrints ID: 437918
URI: http://eprints.soton.ac.uk/id/eprint/437918
ISSN: 0035-8711
PURE UUID: 2a2b40cf-aff1-422a-a5b9-765c25a824a5

## Catalogue record

Date deposited: 24 Feb 2020 17:30

## Contributors

Author: Nick Higginbottom
Author: Stuart A. Sim
Author: Knox S. Long
Author: James H. Matthews
Author: Henrietta A. Hewitt
Author: Edward J. Parkinson
Author: Sam W. Mangham