Abstract
At present, all physical models of diffuse Galactic -ray emission assume that the distribution of cosmic-ray sources traces the observed populations of either OB stars, pulsars, or supernova remnants. However, since -rich regions host significant star formation and numerous supernova remnants, the morphology of observed gas (as traced by CO line surveys) should also provide a physically motivated, high-resolution tracer for cosmic-ray injection. We assess the impact of utilizing as a tracer for cosmic-ray injection on models of diffuse Galactic -ray emission. We employ state-of-the-art 3D particle diffusion and gas density models, along with a physical model for the star-formation rate based on global Schmidt laws. Allowing a fraction, , of cosmic-ray sources to trace the observed density, we find that a theoretically well-motivated value (i) provides a significantly better global fit to the diffuse Galactic -ray sky and (ii) highly suppresses the intensity of the residual -ray emission from the Galactic center region. Specifically, in models utilizing our best global fit values of , the spectrum of the galactic center -ray excess is drastically affected, and the morphology of the excess becomes inconsistent with predictions for dark matter annihilation.
- Received 15 October 2015
DOI:https://doi.org/10.1103/PhysRevLett.117.111101
© 2016 American Physical Society