Cosmic-Ray Injection from Star-Forming Regions
Skip to main content
eScholarship
Open Access Publications from the University of California

Cosmic-Ray Injection from Star-Forming Regions

  • Author(s): Carlson, E
  • Profumo, S
  • Linden, T
  • et al.
Abstract

At present, all physical models of diffuse Galactic gamma-ray emission assume that the distribution of cosmic-ray sources traces the observed populations of either OB stars, pulsars, or supernova remnants. However, since H2-rich regions host significant star formation and numerous supernova remnants, the morphology of observed H2 gas should also provide a physically motivated, high-resolution tracer for cosmic-ray injection. We assess the impact of utilizing H2 as a tracer for cosmic-ray injection on models of diffuse Galactic gamma-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, f_H2, of cosmic-ray sources to trace the observed H2 density, we find that a theoretically well-motivated value f_H2 ~ 0.20 -- 0.25 (i) provides a significantly better global fit to the diffuse Galactic gamma-ray sky and (ii) highly suppresses the intensity of the residual gamma-ray emission from the Galactic center region. Specifically, in models utilizing our best global fit values of f_H2 ~ 0.20 -- 0.25, the spectrum of the galactic center gamma-ray excess is drastically affected, and the morphology of the excess becomes inconsistent with predictions for dark matter annihilation.

Many UC-authored scholarly publications are freely available on this site because of the UC Academic Senate's Open Access Policy. Let us know how this access is important for you.

Main Content
Current View