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Paper IPM / Astronomy / 13924

School of Astronomy

Title:

Constraints on dark matter annihilations from diffuse gamma-ray emission in the Galaxy

Author(s):

1 .	M. Tavakoli
2 .	I. Cholis
3 .	C. Evoli
4 .	P. Ullio

Status:

Published

Journal:

JCAP

Vol.:

2014

Year:

2014

Pages:

Supported by:

IPM

Abstract:

Recent advances in Î³-ray cosmic ray, infrared and radio astronomy have allowed us to develop a significantly better understanding of the galactic medium properties in the last few years. In this work using the DRAGON code, that numerically solves the CR propagation equation and calculating Î³-ray emissivities in a 2-dimensional grid enclosing the Galaxy, we study in a self consistent manner models for the galactic diffuse Î³-ray emission. Our models are cross-checked to both the available CR and Î³-ray data. We address the extend to which dark matter annihilations in the Galaxy can contribute to the diffuse Î³-ray flux towards different directions on the sky. Moreover we discuss the impact that astrophysical uncertainties of non DM nature, have on the derived Î³-ray limits. Such uncertainties are related to the diffusion properties on the Galaxy, the interstellar gas and the interstellar radiation field energy densities. Light 10 GeV dark matter annihilating dominantly to hadrons is more strongly constrained by Î³-ray observations towards the inner parts of the Galaxy and influenced the most by assumptions of the gas distribution; while TeV scale DM annihilating dominantly to leptons has its tightest constraints from observations towards the galactic center avoiding the galactic disk plane, with the main astrophysical uncertainty being the radiation field energy density. In addition, we present a method of deriving constraints on the dark matter distribution profile from the diffuse Î³-ray spectra. These results critically depend on the assumed mass of the dark matter particles and the type of its end annihilation products.

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