PeV IceCube signals and Dark Matter relic abundance in modified cosmologies

G Lambiase,An Stabile,S Mohanty

doi:10.1140/epjc/s10052-018-5821-1

Abstract

The discovery by the IceCube experiment of a high-energy astrophysical neutrino flux with energies of the order of PeV, has opened new scenarios in astroparticles physics. A possibility to explain this phenomenon is to consider the minimal models of Dark Matter (DM) decay, the 4-dimensional operator sim y_{alpha chi }overline{{L_{L_{alpha }}}}, H, chi , which is also able to generate the correct abundance of DM in the Universe. Assuming that the cosmological background evolves according to the standard cosmological model, it follows that the rate of DM decay Gamma _chi sim |y_{alpha chi }|^2 needed to get the correct DM relic abundance (Gamma _chi sim 10^{-58}) differs by many orders of magnitude with respect that one needed to explain the IceCube data (Gamma _chi sim 10^{-25}), making the four-dimensional operator unsuitable. In this paper we show that assuming that the early Universe evolution is governed by a modified cosmology, the discrepancy between the two the DM decay rates can be reconciled, and both the IceCube neutrino rate and relic density can be explained in a minimal model.

Highlights

Unitarity bounds on the cross section of the Dark Matter (DM) [26,27] ruled out the possibility of a thermal relic density of PeV scale DM whose annihilation or decay could produce the IceCube neutrinos
If the neutrino flux at IceCube were to be from DM annihilation into neutrinos the same the same decay rate nχ /τχ must be equal to the annihilation rate n2χ σ v which implies that σ v−1 10−17cm3/s which is again ruled out from unitarity constrains [26,27]
This implies that PeV DM decay with lifetime 1028 s is the prefered mechanism for explaining the IceCube neutrinos, if at all they originate from DM

Summary

Introduction

Unitarity bounds on the cross section of the DM [26,27] ruled out the possibility of a thermal relic density of PeV scale DM whose annihilation or decay could produce the IceCube neutrinos. C (2018) 78:350 from Type Ia Supernovae [32,33], CMB radiation [34,35], and the large scale structure [36,37], suggest that there are strong evidences that the present cosmic expansion of the Universe is accelerating The latter is ascribed to the existence of Dark Energy (DE), an exotic form of energy characterized by a negative pressure that at late times dominates over the cold and dark matter, driving the Universe to the observed accelerating phase, and new ingredients, such as DM and Dark Energy (DE), are required [38,39,40,41,42,43,44,45,46,47,48,49,50].

PeV neutrinos and Ice Cube data

PeV neutrinos in modified cosmologies

Examples of modified cosmologies

Brans–Dicke theory

Conclusions