  Chandra and XMM-Newton observations of the Cartwheel galaxy show ~17 bright
X-ray sources (>~5x10^38 erg s^-1), all within the gas-rich outer ring. We
explore the hypothesis that these X-ray sources are powered by
intermediate-mass black holes (IMBHs) accreting gas or undergoing mass transfer
from a stellar companion. To this purpose, we run N-body/SPH simulations of the
galaxy interaction which might have led to the formation of Cartwheel, tracking
the dynamical evolution of two different IMBH populations: halo and disc IMBHs.
Halo IMBHs cannot account for the observed X-ray sources, as only a few of them
cross the outer ring. Instead, more than half of the disc IMBHs are pulled in
the outer ring as a consequence of the galaxy collision. However, also in the
case of disc IMBHs, accretion from surrounding gas clouds cannot account for
the high luminosities of the observed sources. Finally, more than 500 disc
IMBHs are required to produce <~15 X-ray sources via mass transfer from very
young stellar companions. Such number of IMBHs is very large and implies
extreme assumptions. Thus, the hypothesis that all the observed X-ray sources
in Cartwheel are associated with IMBHs is hardly consistent with our
simulations, even if it is still possible that IMBHs account for the few
(<~1-5) brightest ultraluminous X-ray sources (ULXs).
