Broad absorption features in wind-dominated ultraluminous X-ray sources?
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.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2014
- DOI:
- 10.1093/mnrasl/slt157
- arXiv:
- arXiv:1309.3134
- Bibcode:
- 2014MNRAS.438L..51M
- Keywords:
-
- accretion;
- accretion discs;
- black hole physics;
- X-rays: binaries;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 5 pages, 1 figure, accepted to MNRAS letters