  It has been proposed that a large population of unresolved millisecond
pulsars (MSPs) could potentially account for the excess of GeV-scale gamma-rays
observed from the region surrounding the Galactic Center. The viability of this
scenario depends critically on the gamma-ray luminosity function of this source
population, which determines how many MSPs Fermi should have already detected
as resolved point sources. In this paper, we revisit the gamma-ray luminosity
function of MSPs, without relying on uncertain distance measurements. Our
determination, based on a comparison of models with the observed
characteristics of the MSP population, suggests that Fermi should have already
detected a significant number of sources associated with such a hypothesized
Inner Galaxy population. We cannot rule out a scenario in which the MSPs
residing near the Galactic Center are systematically less luminous than those
present in the Galactic Plane or within globular clusters.
