The Galactic-Centre GeV Excess: Pulsar Bookkeeping versus the Annihilation Price

Fermi-LAT sees an extended GeV excess toward the Galactic centre. From an adopted excess luminosity of 2.90e37 erg/s, a disk-like millisecond pulsar population requires 48,271 pulsars, of which about 20 should already have been resolved by Fermi versus 3 observed (shortfall factor 6.7), and requires 3,218 MSPs per 1e9 solar masses of bulge stars, 6.4 times the field rate. Annihilation of 49 GeV dark matter into b-bbar requires = 3.32e-26 cm3/s for a gamma=1.2 halo, a factor 1.75 above the Fermi 14-year dwarf-spheroidal limit at the same mass point. Neither reading closes perfectly; the annihilation reading is short by about a factor of two, the disk-like pulsar reading by factors of six to seven.