Constraints on Lorentz invariance violation from the extraordinary Mrk 421 flare of 2014 using a novel analysis method

TL;DR

This paper uses a novel likelihood method to analyze a 2014 Mrk 421 flare, setting new constraints on Lorentz invariance violation energy scales by examining energy-dependent photon time delays.

Contribution

It introduces a new binned-likelihood approach to constrain LIV using astrophysical data, improving limits on quantum gravity energy scales from gamma-ray observations.

Findings

Lower limits on LIV energy scale for linear scenario: >2.7×10^{17} GeV (subluminal), >3.6×10^{17} GeV (superluminal)

Lower limits for quadratic scenario: >2.6×10^{10} GeV (subluminal), >2.5×10^{10} GeV (superluminal)

First application of this method to LIV constraints using a blazar flare.

Abstract

The Lorentz Invariance Violation (LIV), a proposed consequence of certain quantum gravity (QG) scenarios, could instigate an energy-dependent group velocity for ultra-relativistic particles. This energy dependence, although suppressed by the massive QG energy scale $E_\mathrm{QG}$, expected to be on the level of the Planck energy $1.22 \times 10^{19}$ GeV, is potentially detectable in astrophysical observations. In this scenario, the cosmological distances traversed by photons act as an amplifier for this effect. By leveraging the observation of a remarkable flare from the blazar Mrk\,421, recorded at energies above 100 GeV by the MAGIC telescopes on the night of April 25 to 26, 2014, we look for time delays scaling linearly and quadratically with the photon energies. Using for the first time in LIV studies a binned-likelihood approach we set constraints on the QG energy scale. For the linear scenario, we set $95\%$ lower limits $E_\mathrm{QG}>2.7\times10^{17}$ GeV for the subluminal case and $E_\mathrm{QG}> 3.6 \times10^{17}$ GeV for the superluminal case. For the quadratic scenario, the $95\%$ lower limits for the subluminal and superluminal cases are $E_\mathrm{QG}>2.6 \times10^{10}$ GeV and $E_\mathrm{QG}>2.5\times10^{10}$ GeV, respectively.