Dark matter and pulsar model constraints from Galactic Center Fermi-LAT gamma-ray observations
Abstract
Employing Fermi-LAT gamma-ray observations, several independent groups have found excess extended gamma-ray emission at the Galactic Center (GC). Both annihilating dark matter (DM) or a population of ∼103 unresolved millisecond pulsars (MSPs) are regarded as well-motivated possible explanations. However, there are significant uncertainties in the diffuse galactic background at the GC. We have performed a revaluation of these two models for the extended gamma-ray source at the GC by accounting for the systematic uncertainties of the Galactic diffuse emission model. We also marginalize over point-source and diffuse background parameters in the region of interest. We show that the excess emission is significantly more extended than a point source. We find that the DM (or pulsar-population) signal is larger than the systematic errors and therefore proceed to determine the sectors of parameter space that provide an acceptable fit to the data. We find that a population of 1000-2000 MSPs with parameters consistent with the average spectral shape of Fermi-LAT measured MSPs is able to fit the GC excess emission. For DM, we find that a pure τ+τ- annihilation channel is not a good fit to the data. But a mixture of τ+τ- and bb¯ with a ⟨σv⟩ of order the thermal relic value and a DM mass of around 20 to 60 GeV provides an adequate fit.
- Publication:
-
Physical Review D
- Pub Date:
- October 2013
- DOI:
- 10.1103/PhysRevD.88.083521
- arXiv:
- arXiv:1306.5725
- Bibcode:
- 2013PhRvD..88h3521G
- Keywords:
-
- 95.35.+d;
- 98.80.-k;
- Dark matter;
- Cosmology;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Cosmology and Extragalactic Astrophysics;
- Astrophysics - Galaxy Astrophysics;
- High Energy Physics - Phenomenology
- E-Print:
- 20 pages, 13 figures, v2: typos corrected and references added