  AM CVn systems are a rare type of cataclysmic variable star consisting of a w
hite dwarf accreting material from a low-mass, hydrogen-poor donor star. These
helium-rich systems usually have orbital periods that are less than 65 minutes
an d are predicted to be sources of gravitational waves. We have analyzed the
catalogued X-ray data from the Chandra, XMM-Newton, and the Neil Gehrels Swift
Observatory (hereafter referred to as 'Swift') to investigate the relationship
between X-ray luminosity and the orbital period of AM CVn systems. We find that
the high accretion-rate systems which are likely to have optically thick
boundary laye rs are sub-luminous in X-rays relative to theoretical model
predictions for the boundary layer luminosity, while the longer orbital period,
lower bolometric luminosity systems match fairly well to the model predictions,
with the exception of an overluminous system which has already been suggested
to show magnetic accretion.
