Millisecond Pulsars from Accretion Induced Collapse naturally explain the Galactic Center Gamma-ray Excess

Anuj Gautam, Roland M. Crocker, Lilia Ferrario, Ashley J. Ruiter, Harrison Ploeg, Chris Gordon, Oscar Macias

Published 2021-06-01Version 1

Gamma-ray data from the Fermi-Large Area Telescope reveal an unexplained, apparently diffuse, signal from the Galactic bulge. The origin of this "Galactic Center Excess" (GCE) has been debated with proposed sources prominently including self-annihilating dark matter and a hitherto undetected population of millisecond pulsars (MSPs). We use a binary population synthesis forward model to demonstrate that an MSP population arising from the accretion induced collapse of O-Ne white dwarfs in Galactic bulge binaries can naturally explain the GCE. Synchrotron emission from MSP-launched cosmic ray electrons and positrons seems also to explain the mysterious "haze" of hard-spectrum, non-thermal microwave emission from the inner Galaxy detected in WMAP and Planck data.