  We consider X-ray binaries (XBs) as potential sources of stellar feedback.
XBs observationally appear able to deposit a high fraction of their power
output into their local interstellar medium, which may make them a
non-negligible source of energy input. The formation rate of the most luminous
XBs rises with decreasing metallicity, which should increase their significance
during galaxy formation in the early universe. We also argue that stochastic
effects are important to XB feedback (XBF) and may dominate the systematic
changes due to metallicity in many cases. Large stochastic variation in the
magnitude of XBF at low absolute star formation rates provides a natural reason
for diversity in the evolution of dwarf galaxies which were initially almost
identical, with several percent of such halos experiencing energy input from
XBs roughly two orders of magnitude above the most likely value. These
probability distributions suggest that the effect of XBF is most commonly
significant for total stellar masses between ~10^7 and 10^8 Msun, which might
resolve a current problem with modelling populations of such galaxies. We
explain how XBs might inject energy before luminous supernovae (SNe) contribute
significantly to feedback and how XBs can assist in keeping gas hot long after
the last core-collapse SN has exploded. [...] XBF could be especially important
to some dwarf galaxies, potentially heating gas without expelling it; the
properties of XBF also match those previously derived as allowing episodic star
formation. We also argue that the efficiency of SN feedback (SNF) might be
reduced when XBF has had the opportunity to act first. In addition, we note
that the effect of SNF is unlikely to be scale-free; galaxies smaller than ~100
pc might well experience less effective SNF. (Slightly abbreviated to fit arXiv
size limit.)
