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arXiv · 1309.3134

Broad absorption features in wind-dominated ULXs?

Matthew J. Middleton·Dominic J. Walton·Timothy P. Roberts·Lucy Heil
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Abstract

The luminosities of ultraluminous X-ray sources (ULXs) require an exotic solution with either super-critical accretion modes onto stellar mass black holes or sub-critical accretion onto 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 super-critical 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, blue-shifted absorption by a partially ionised, 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.

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Matthew J. Middleton, Dominic J. Walton, Timothy P. Roberts, Lucy Heil. 2013-10-31. Broad absorption features in wind-dominated ULXs?. https://doi.org/10.1093/mnrasl%2Fslt157

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