GRB neutrinos, Lorenz Invariance Violation and the influence of background cosmology

TL;DR

This paper examines how uncertainties in cosmological models, especially dark energy, affect the use of high-energy neutrino time delays from gamma-ray bursts to test Lorentz Invariance Violation, highlighting significant potential ambiguities.

Contribution

It analyzes the impact of different dark energy models on neutrino time delay predictions, emphasizing the importance of cosmological background knowledge in LIV tests.

Findings

Uncertainty in dark energy models significantly affects LIV bounds.

Different cosmological scenarios produce varying neutrino time delay predictions.

Knowledge of background cosmology is crucial for accurate LIV testing.

Abstract

Modern ideas in quantum gravity predict the possibility of Lorenz Invariance Violation (LIV) manifested e.g. by energy dependent modification of standard relativistic dispersion relation. In a recent paper Jacob and Piran proposed that time of flight delays in high energy neutrinos emitted by gamma ray bursts (GRBs) located at cosmological distances can become a valuable tool for setting limits on LIV theories. However, current advances in observational cosmology suggest that our Universe is dominated by dark energy with relatively little guidance on its nature thus leading to several cosmological scenarios compatible with observations. In this paper we raise the issue of how important, in the context of testing LIV theories, is our knowledge of background cosmological model. Specifically we calculate expected time lags for high-energy (100 TeV) neutrinos in different cosmological models. Out of many particular models of dark energy we focus on five: $\Lambda$CDM, quintessence, quintessence with time varying equation of state, brane-world and generalized Chaplygin gas model as representative for various competing approaches. The result is that uncertainty introduced by our ignorance concerning the right phenomenological model describing dark energy dominated universe is considerable and may obscure bounds derived from studying time delays from cosmological sources.