Astrophysical limitations to the identification of dark matter: indirect neutrino signals vis-a-vis direct detection recoil rates

TL;DR

This paper examines how astrophysical uncertainties impact the combined analysis of direct detection and neutrino signals for identifying dark matter, highlighting the limitations these uncertainties impose on parameter reconstruction.

Contribution

It demonstrates that astrophysical uncertainties affect direct detection and neutrino signals differently, constraining the effectiveness of combined dark matter detection strategies.

Findings

Uncertainties in astrophysical parameters can cause up to a factor of two variation in signal ratios.

Different physical quantities depend on astrophysical parameters in distinct ways.

Astrophysical uncertainties limit the precision of dark matter parameter reconstruction.

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.