Binary Evolution Constraints from Luminosity Functions of LMXBs

The formation and evolution of low-mass X-ray binaries (LMXBs) is not well understood. The properties of a population of LMXBs depend on a number of uncertain aspects of binary evolution, and population studies offers a relatively new way of probing binary interactions. We have studied the shape of the faint end of the X-ray luminosity function (LF) of LMXBs in nearby galaxies with Chandra and in the Milky Way using the Swift all-sky monitor. We find a clear difference between the LF of LMXBs in globular clusters (GCs) and those outside, with a relative lack of faint GC sources. This indicates a difference in the composition of the two populations.