Skip to main content

Research Repository

Advanced Search

Thermal stability of winds driven by radiation pressure in super-Eddington accretion discs

Pinto, C.; Mehdipour, M.; Walton, D.J.; Middleton, M.J.; Roberts, T.P.; Fabian, A.C.; Guainazzi, M.; Soria, R.; Kosec, P.; Ness, J. -U.

Thermal stability of winds driven by radiation pressure in super-Eddington accretion discs Thumbnail


C. Pinto

M. Mehdipour

D.J. Walton

M.J. Middleton

A.C. Fabian

M. Guainazzi

R. Soria

P. Kosec

J. -U. Ness


Ultraluminous X-ray sources (ULXs) are mainly powered by accretion in neutron stars or stellar-mass black holes. Accreting at rates exceeding the Eddington limit by factors of a few up to hundreds, radiation pressure is expected to inflate the accretion disc, and drive fast winds that have in fact been observed at significant fractions of the speed of light. Given the super-Eddington luminosity, the accretion disc will be thicker than in sub-Eddington accretors such as common active galactic nuclei and X-ray binaries, leading to a different spectral energy distribution and, possibly, a different thermal status of the wind. Here, we show the first attempt to calculate the photoionization balance of the winds driven by strong radiation pressure in thick discs with a focus on ULXs hosting black holes or non-magnetic neutron stars. We find that the winds are generally in thermally stable equilibrium, but long-term variations in the accretion rate and the inclination due to precession may have significant effects on the wind appearance and stability. Our model trends can explain the observed correlation between the spectral residuals around 1 keV and the ULX spectral state. We also find a possible correlation between the spectral hardness of the ULX, the wind velocity, and the ionization parameter in support of the general scenario.


Pinto, C., Mehdipour, M., Walton, D., Middleton, M., Roberts, T., Fabian, A., …Ness, J. -. (2020). Thermal stability of winds driven by radiation pressure in super-Eddington accretion discs. Monthly Notices of the Royal Astronomical Society, 491(4), 5702-5716.

Journal Article Type Article
Acceptance Date Dec 1, 2019
Online Publication Date Dec 5, 2019
Publication Date Feb 28, 2020
Deposit Date Dec 17, 2019
Publicly Available Date Jan 10, 2020
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 491
Issue 4
Pages 5702-5716
Related Public URLs


Published Journal Article (1.3 Mb)

Copyright Statement
This article has been accepted for publication in the Monthly notices of the Royal Astronomical Society ©: 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

You might also like

Downloadable Citations