Broad absorption features in wind-dominated ultraluminous X-ray sources?

Middleton, M.J.; Walton, D.J.; Roberts, T.P.; Heil, L.

Abstract

The luminosities of ultraluminous X-ray sources (ULXs) require an exotic solution with either supercritical accretion modes on to stellar-mass black holes or subcritical accretion on to intermediate-mass black holes (IMBHs) being invoked. Discriminating between the two is non-trivial due to the present lack of a direct mass measurement. A key expectation of the supercritical mode of accretion is the presence of powerful radiatively driven winds. Here we analyse XMM–Newton data from NGC 5408 X-1 and NGC 6946 X-1 and find that strong soft residuals present in the X-ray spectra can be reconciled with broadened, blueshifted absorption by a partially ionized, optically thin phase of this wind. We derive initial values for the physical parameters of the wind; we also discuss other possible origins for the observed features.

Citation

Middleton, M., Walton, D., Roberts, T., & Heil, L. (2014). Broad absorption features in wind-dominated ultraluminous X-ray sources?. Monthly Notices of the Royal Astronomical Society, 438(1), L51-L55. https://doi.org/10.1093/mnrasl/slt157

• Journal Article Type: Article
• Acceptance Date: Oct 30, 2013
• Online Publication Date: Dec 12, 2013
• Publication Date: Feb 11, 2014
• Deposit Date: Jan 24, 2014
• Publicly Available Date: Jan 29, 2014
• 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: 438
• Issue: 1
• Pages: L51-L55
• DOI: https://doi.org/10.1093/mnrasl/slt157
• Keywords: Accretion discs, Black hole physics, X-rays, Binaries.