Bounds on Dark Matter Properties from Radio Observations of Ursa Major II using the Green Bank Telescope
Physical Review D
Radio observations of the Ursa Major II dwarf spheroidal galaxy obtained using the Green Bank Telescope are used to place bounds on weakly interacting massive particle (WIMP) dark matter properties. Dark matter annihilation releases energy in the form of charged particles which emit synchrotron radiation in the magnetic field of the dwarf galaxy. We compute the expected synchrotron radiation intensity from WIMP annihilation to various primary channels. The predicted synchrotron radiation is sensitive to the distribution of dark matter in the halo, the diffusion coefficient D0, the magnetic field strength B, the particle mass mχ, the annihilation rate ⟨σav⟩, and the annihilation channel. Limits on ⟨σav⟩, mχ, B, and D0 are obtained for the e+e−, μ+μ−, τ+τ−, and bb¯ channels. Constraints on these parameters are sensitive to uncertainties in the measurement of the dark matter density profile. For the best fit halo parameters derived from stellar kinematics, we exclude 10 GeV WIMPs annihilating directly to e+e− at the thermal rate ⟨σav⟩=2.18×10−26 cm3/s at the 2σ level, for B>0.6 μG (1.6 μG) and D0=0.1(1.0)× the Milky Way diffusion value.
Natarajan, A., Peterson, J., Voytek, T., Spekkens, K., Mason, B., Aguirre, J., Willman, B., 2013, Bounds on Dark Matter Properties from Radio Observations of Ursa Major II using the Green Bank Telescope, Phys Rev D, 88, 8