Pamela, FGST and Sub-Tev Dark Matter

Abstract

PAMELA's observation that the cosmic ray positron fraction increases rapidly with energy implies the presence of primary sources of energetic electron-positron pairs. Of particular interest is the possibility that dark matter annihilations in the halo of the Milky Way provide this anomalous flux of antimatter. The recent measurement of the cosmic ray electron spectrum by the Fermi Gamma Ray Space Telescope, however, can be used to constrain the nature of any such dark matter particle. In particular, it has been argued that in order to accommodate the observations of Fermi and provide the PAMELA positron excess, annihilating dark matter particles must be as massive as ~1 TeV or heavier. In this article, we revisit Fermi's electron spectrum measurement within the context of annihilating dark matter, focusing on masses in the range of 100-1000 GeV, and considering effects such as variations in the astrophysical backgrounds from the presence of local cosmic ray accelerators, and the finite energy resolution of the Fermi Gamma Ray Space Telescope. When these factors are taken into account, we find that dark matter particles as light as ~300 GeV can be capable of generating the positron fraction observed by PAMELA.

16 pages, 10 figures

References in corpus (13)

• Observation of an anomalous positron abundance in the cosmic radiation
• A Theory of Dark Matter
• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• A new measurement of the antiproton-to-proton flux ratio up to 100 GeV in the cosmic radiation
• Dark Matter and Collider Phenomenology of Universal Extra Dimensions
• Cosmic-ray positron fraction measurement from 1 to 30 GeV with AMS-01
• The Role of Antimatter Searches in the Hunt for Supersymmetric Dark Matter
• Cosmic Rays from Leptophilic Dark Matter Decay via Kinetic Mixing
• Klein-Nishina steps in the energy spectrum of galactic cosmic ray electrons
• Anomaly Induced Dark Matter Decay and PAMELA/ATIC Experiments
• Extended MSSM Neutralinos as the Source of the PAMELA Positron Excess
• PAMELA/ATIC Anomaly from Exotic Mediated Dark Matter Decay
• Astrophysical Uncertainties in the Cosmic Ray Electron and Positron Spectrum From Annihilating Dark Matter

Cited by in corpus (6)

• Dark Matter and Pulsar Origins of the Rising Cosmic Ray Positron Fraction in Light of New Data From AMS
• Dark Matter Subhalos In the Fermi First Source Catalog
• Goldstini as the decaying dark matter
• Decaying Dark Matter in Supersymmetric Model and Cosmic-Ray Observations
• Constraint on dark matter annihilation with dark star formation using Fermi extragalactic diffuse gamma-ray background data
• Synchrotron Emission From Young And Nearby Pulsars