Publication details for Prof Tim RobertsSiwek, M., Sadowski, A., Narayan, R., Roberts, T.P. & Soria, R. (2017). Optical and X-ray luminosity of expanding nebulae around ultraluminous X-ray sources. Monthly Notices of the Royal Astronomical Society 470(1): 361-371.
- Publication type: Journal Article
- ISSN/ISBN: 0035-8711, 1365-2966
- DOI: 10.1093/mnras/stx1185
- Further publication details on publisher web site
- Durham Research Online (DRO) - may include full text
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Author(s) from Durham
We have performed a set of simulations of expanding, spherically symmetric nebulae inflated by winds from
accreting black holes in ultraluminous X-ray sources (ULXs). We implemented a realistic cooling function
to account for free-free and bound-free cooling. For all model parameters we considered, the forward shock
in the interstellar medium becomes radiative at a radius ∼ 100 pc. The emission is primarily in the optical
and UV, and the radiative luminosity is about 50% of the total kinetic luminosity of the wind. In contrast,
the reverse shock in the wind is adiabatic so long as the terminal outflow velocity of the wind vw & 0.003c.
The shocked wind in these models radiates in X-rays, but with a luminosity of only ∼ 1035 erg s−1
. For wind
velocities vw . 0.001c, the shocked wind becomes radiative, but it is no longer hot enough to produce Xrays.
Instead it emits in optical and UV, and the radiative luminosity is comparable to 100% of the wind
kinetic luminosity. We suggest that measuring the optical luminosities and putting limits on the X-ray and
radio emission from shock-ionized ULX bubbles may help in estimating the mass outflow rate of the central
accretion disk and the velocity of the outflow.