The Isotropic Radio Background and Annihilating Dark Matter
- Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
- Institut d'Astrophysique (France)
- Univ. of California, Santa Cruz, CA (United States)
- Princeton Univ., Princeton, NJ (United States)
Observations by ARCADE-2 and other telescopes sensitive to low frequency radiation have revealed the presence of an isotropic radio background with a hard spectral index. The intensity of this observed background is found to exceed the flux predicted from astrophysical sources by a factor of approximately 5-6. In this article, we consider the possibility that annihilating dark matter particles provide the primary contribution to the observed isotropic radio background through the emission of synchrotron radiation from electron and positron annihilation products. For reasonable estimates of the magnetic fields present in clusters and galaxies, we find that dark matter could potentially account for the observed radio excess, but only if it annihilates mostly to electrons and/or muons, and only if it possesses a mass in the range of approximately 5-50 GeV. For such models, the annihilation cross section required to normalize the synchrotron signal to the observed excess is sigma v ~ (0.4-30) x 10^-26 cm^3/s, similar to the value predicted for a simple thermal relic (sigma v ~ 3 x 10^-26 cm^3/s). We find that in any scenario in which dark matter annihilations are responsible for the observed excess radio emission, a significant fraction of the isotropic gamma ray background observed by Fermi must result from dark matter as well.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1155782
- Report Number(s):
- FERMILAB-PUB-12-072-A; arXiv eprint number arXiv:1203.3547
- Journal Information:
- Physical Review. D, Particles, Fields, Gravitation and Cosmology, Vol. 86, Issue 10; ISSN 1550-7998
- Publisher:
- American Physical Society (APS)
- Country of Publication:
- United States
- Language:
- English
Similar Records
The Empirical Case For 10 GeV Dark Matter
CONSTRAINTS ON DARK MATTER ANNIHILATION IN CLUSTERS OF GALAXIES FROM DIFFUSE RADIO EMISSION