Probing Lorentz invariance with a high-energy neutrino flare

TL;DR

This paper develops non-parametric statistical methods to test Lorentz invariance violation using high-energy neutrino flares, providing robust limits on LIV energy scales based solely on neutrino timing data.

Contribution

It introduces novel statistical techniques to detect LIV effects in neutrino data independently of source emission models, with application to IceCube observations.

Findings

LIV energy scale exceeds 10^{14} GeV (linear)

LIV energy scale exceeds 10^9 GeV (quadratic)

Methods are robust against source timing uncertainties

Abstract

Time-of-flight measurements of high-energy astrophysical neutrinos can be used to probe Lorentz invariance, a pillar of modern physics. If Lorentz-invariance violation (LIV) occurs, it could cause neutrinos to slow down, with the delay scaling linearly or quadratically with their energy. We introduce non-parametric statistical methods designed to detect LIV-induced distortions in the temporal structure of a high-energy neutrino flare as it travels to Earth from a distant astrophysical source, independently of the intrinsic timing properties of the source. Our approach, illustrated using the 2014/2015 TeV-PeV neutrino flare from the blazar TXS 0506+056 detected by IceCube, finds that the LIV energy scale must exceed 10^{14} GeV (linear) or 10^9 GeV (quadratic). Our methods provide a robust means to investigate LIV by focusing solely on a neutrino flare, without relying on electromagnetic counterparts, and account for realistic energy and directional uncertainties. For completeness, we compare our limits inferred from TXS 0506+056 to the sensitivity inferred from multi-messenger detection of tentative coincidences between neutrinos and electromagnetic emission from active galactic nuclei and tidal disruption events.