Search for Lorentz Invariance Violation with spectral lags of GRB 190114C using profile likelihood

We search for Lorentz invariance violation (LIV) by re-analyzing the spectral lag data for GRB 190114C from Fermi-GBM using frequentist analysis, where we deal with the astrophysical nuisance parameters using profile likelihood. For this use case, we find a global minima for the $χ^2$ as a function of energy scale of LIV ($E_{QG}$), well below the Planck scale. The best-fit $1σ$ central intervals for $E_{QG}$ are given by $2.81^{+0.50}{-0.37}\times 10^{14}$ GeV and $9.85^{+0.84}{-0.60}\times 10^{5}$ GeV for linear and quadratic LIV, respectively, and agree with the Bayesian estimates obtained so far in a previous work. Therefore, the results from the frequentist analysis of GRB 190114C agree with Bayesian analysis.

💡 Research Summary

This paper investigates possible Lorentz invariance violation (LIV) using the spectral lag measurements of GRB 190114C obtained with Fermi‑GBM. The authors adopt a frequentist framework, employing a profile‑likelihood technique to treat the astrophysical nuisance parameters (the intrinsic lag amplitude τ and spectral index α) while scanning over the quantum‑gravity energy scale E_QG that characterises LIV.

The observed lag for each energy band i is modeled as Δt_exp = (1+z)Δt_int + Δt_LIV, where the intrinsic lag follows a power‑law Δt_int = τ