Constraining Supersymmetric Dark Matter With Synchrotron Measurements

TL;DR

This paper uses WMAP synchrotron measurements to place stringent constraints on neutralino dark matter annihilation cross sections, surpassing other indirect detection methods and impacting models with non-thermal production.

Contribution

It introduces a novel constraint on neutralino dark matter annihilation cross sections based on synchrotron emission data from WMAP, improving upon previous indirect detection limits.

Findings

Synchrotron measurements constrain neutralino annihilation cross section to below ~3 x 10^-26 cm^3/s for 100 GeV neutralinos.

Constraints are less strict (~30 times) for flat dark matter distributions within the Milky Way.

Results challenge non-thermal production scenarios for wino or higgsino neutralino dark matter.

Abstract

The annihilations of neutralino dark matter (or other dark matter candidate) generate, among other Standard Model states, electrons and positrons. These particles emit synchrotron photons as a result of their interaction with the Galactic Magnetic Field. In this letter, we use the measurements of the WMAP satellite to constrain the intensity of this synchrotron emission and, in turn, the annihilation cross section of the lightest neutralino. We find this constraint to be more stringent than that provided by any other current indirect detection channel. In particular, the neutralino annihilation cross section must be less than ~ 3 x 10^-26 cm^3/s (1 x 10^25 cm^3/s) for 100 GeV (500 GeV) neutralinos distributed with an NFW halo profile. For the conservative case of an entirely flat dark matter distribution within the inner 8 kiloparsecs of the Milky Way, the constraint is approximately a factor of 30 less stringent. Even in this conservative case, synchrotron measurements strongly constrain, for example, the possibility of wino or higgsino neutralino dark matter produced non-thermally in the early universe.