Cascade Events at IceCube+DeepCore as a Definitive Constraint on the Dark Matter Interpretation of the PAMELA and Fermi Anomalies

TL;DR

This paper demonstrates that measuring cascade events in IceCube+DeepCore provides a faster and more robust way to constrain dark matter decay and annihilation models explaining cosmic ray anomalies, compared to previous methods.

Contribution

It introduces the use of cascade event measurements in IceCube+DeepCore to more quickly and robustly constrain dark matter decay and annihilation scenarios.

Findings

Cascade measurements can rule out mu+mu- decays in 3 years.

Cascade measurements can exclude tau+tau- decays and mu+mu- annihilations in 1 year.

Constraints are robust against halo profile variations.

Abstract

Dark matter decaying or annihilating into mu+mu- or tau+tau- has been proposed as an explanation for the e+e- anomalies reported by PAMELA and Fermi. Recent analyses show that IceCube, supplemented by DeepCore, will be able to significantly constrain the parameter space of decays to mu+mu-, and rule out decays to tau+tau- and annihilations to mu+mu- in less than five years of running. These analyses rely on measuring track-like events in IceCube+DeepCore from down-going nu_mu. In this paper we show that by instead measuring cascade events, which are induced by all neutrino flavors, IceCube+DeepCore can rule out decays to mu+mu- in only three years of running, and rule out decays to tau+tau- and annihilation to mu+mu- in only one year of running. These constraints are highly robust to the choice of dark matter halo profile and independent of dark matter-nucleon cross-section.