2010ApJ...721.1523K

We have compared the combined X-ray luminosity function (XLF) of low-mass X-ray binaries (LMXBs) detected in Chandra observations of young, post-merger elliptical galaxies with that of typical old elliptical galaxies. We find that the XLF of the "young" sample does not present the prominent high-luminosity break at L_X> 5x10³⁸ erg/s found in the old elliptical galaxy XLF. The "young" and "old" XLFs differ with a 3σ statistical significance (with a probability less than 0.2% that they derive from the same underlying parent distribution). Young elliptical galaxies host a larger fraction of luminous LMXBs (L_X> 5x10³⁸ erg/s) than old elliptical galaxies and the XLF of the young galaxy sample is intermediate between that of typical old elliptical galaxies and that of star-forming galaxies. This observational evidence may be related to the last major/minor mergers and the associated star formation.