Optical and radio observations of shock-ionised bubble nebulae surrounding ultraluminous X-ray sources ( ULXs ) suggest that they are powered by jets or super-critical outflows presumably launched from the ULX accretion disc .
Recent simulations of these systems have shown that the shocked wind can emit thermal X-rays with estimated luminosities \lesssim 10 ^ { 36 } erg s ^ { -1 } .
In this work , we investigated whether it is possible to detect and spatially resolve the X-ray emission from these systems using archival Chandra observations of the ULX Holmberg IX X-1 .
This source is an ideal target to study for two reasons : it is surrounded by an optical bubble nebula with a large spatial extent ( \sim 400 pc ) that can easily be resolved with Chandra .
Further , it has a hard X-ray continuum that is easily distinguishable from the expected soft thermal emission from the nebula .
However , a spectral and photometric analysis on stacked Chandra observations of the source reveals that there is no strong evidence for an X-ray bubble associated with it , to a limiting luminosity of \sim 2 \times 10 ^ { 36 } erg s ^ { -1 } .
The detection of such X-ray nebulae may be possible with future X-ray missions such as Athena , which would provide useful constraints on the kinematics of the outflow .
Finally , our observations also emphasise that the nebular emission does not contribute significantly to the residuals in the X-ray spectrum of the source , which are more likely to be linked to processes localised to the ULX .