The population of low-luminosity (< 1035 erg s-1) X-Ray Binaries (XRBs) has been investigated
in our Galaxy and M31 but not further. To address this problem, we have used data from the
Chandra X-Ray Observatory and the Hubble Space Telescope to investigate the faint population of
XRBs in the grand-design spiral galaxy M51. A matching analysis found 25 star clusters coincident
with 20 X-ray point sources within 1.5'' (60 pc). From X-ray and optical color-color plots we determine
that this population is dominated by high-mass XRBs. A stacking analysis of the X-ray data at the
positions of optically-identified star clusters was completed to probe low-luminosity X-ray sources.
No cluster type had a significant detection in any X-ray energy band. An average globular cluster
had the largest upper limit, 9.23x1034 erg s-1, in the full-band (0.3 - 8 keV) while on average the
complete sample of clusters had the lowest upper limit, 6.46x1033 erg s-1 in the hard-band (2 - 8
keV). We determined average luminosities of the young and old star cluster populations and compared
the results to those from the Milky Way. We conclude that deeper X-ray data is required to identify
faint sources with a stacking analysis.