Astrophysical limitations to the identification of dark matter: Indirect neutrino signalsvis-à-visdirect detection recoil rates

Abstract

A convincing identification of dark matter (DM) particles can probably be achieved only through a combined analysis of different detections strategies, which provides an effective way of removing degeneracies in the parameter space of DM models. In practice, however, this program is made complicated by the fact that different strategies depend on different physical quantities, or on the same quantities but in a different way, making the treatment of systematic errors rather tricky. We discuss here the uncertainties on the recoil rate in direct detection experiments and on the muon rate induced by neutrinos from dark matter annihilations in the Sun, and we show that, contrarily to the local DM density or overall cross section scale, irreducible astrophysical uncertainties affect the two rates in a different fashion, therefore limiting our ability to reconstruct the parameters of the dark matter particle. By varying within their respective errors astrophysical parameters such as the escape velocity and the velocity dispersion of dark matter particles, we show that the uncertainty on the relative strength of the neutrino and direct-detection signal is as large as a factor of two for typical values of the parameters, but can be even larger in some circumstances.PACS numbers: 95.35.+d, 14.60.Lm

Assessing the discovery potential of directional detection of dark matter

“…Directional detection depends crucially on the local WIMP velocity distribution [34][35][36]. The isothermal sphere halo model is often considered but it is worth going beyond this standard paradigm when trying to account for all astrophysical uncertainties.…”

Determining the dark matter mass with DeepCore

“…We note, though, that this uncertainty could be substantially reduced [14]. However, other sources of systematic errors, such as the astrophysical uncertainties in the calculation of the capture rate, could also affect the results [20]. All in all, we add an overall 15% systematic error in our computations as a conservative assumption.…”

Dark Matter searches: the nightmare scenario

“…Including the uncertainty on the local DM density [97,98] would not change the fraction of cMSSM points accessible to direct detection experiments, since the SUSY points and the sensitivity curves would be rescaled by the same quantity (i.e., the ratio of the 'true' local density over the value adopted here). A more careful treatment of the velocity distribution and of the hadronic uncertainties in the neutralino-nucleon cross-section may instead have a stronger impact on direct and indirect searches [82,99,96], but given the ample margin between the bulk of the nightmare cMSSM parameter space and the sensitivity of Phase 3 direct detection experiments, it is unlikely that our main conclusion would change significantly.…”