Constraint on Lorentz Invariance Violation for spectral lag transition in GRB 160625B using profile likelihood

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Main Authors: Desai, Shantanu, Ganguly, Shalini
Format: Preprint
Published: 2024
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author Desai, Shantanu
Ganguly, Shalini
author_facet Desai, Shantanu
Ganguly, Shalini
contents We reanalyze the spectral lag data for GRB 160625B using frequentist inference in order to constrain the energy scale ($E_{QG}$) of Lorentz Invariance Violation (LIV). For this purpose, we use profile likelihood to deal with the astrophysical nuisance parameters. This is in contrast to Bayesian inference implemented in previous works, where marginalization was carried out over the nuisance parameters. We show that with profile likelihood, we do not find a global minimum for $χ^2$ as a function of $E_{QG}$ below the Planck scale for both linear and quadratic models of LIV, whereas bounded credible intervals were previously obtained using Bayesian inference. Therefore, we can set one-sided lower limits in a straightforward manner. We find that $E_{QG} \geq 2.55 \times 10^{16}$ GeV and $E_{QG} \geq 1.85 \times 10^7$ GeV at 95\% c.l., for linear and quadratic LIV, respectively. Therefore, this is the first proof-of-principles application of profile likelihood method to the analysis of GRB spectral lag data to constrain LIV.
format Preprint
id arxiv_https___arxiv_org_abs_2411_09248
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Constraint on Lorentz Invariance Violation for spectral lag transition in GRB 160625B using profile likelihood
Desai, Shantanu
Ganguly, Shalini
High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
We reanalyze the spectral lag data for GRB 160625B using frequentist inference in order to constrain the energy scale ($E_{QG}$) of Lorentz Invariance Violation (LIV). For this purpose, we use profile likelihood to deal with the astrophysical nuisance parameters. This is in contrast to Bayesian inference implemented in previous works, where marginalization was carried out over the nuisance parameters. We show that with profile likelihood, we do not find a global minimum for $χ^2$ as a function of $E_{QG}$ below the Planck scale for both linear and quadratic models of LIV, whereas bounded credible intervals were previously obtained using Bayesian inference. Therefore, we can set one-sided lower limits in a straightforward manner. We find that $E_{QG} \geq 2.55 \times 10^{16}$ GeV and $E_{QG} \geq 1.85 \times 10^7$ GeV at 95\% c.l., for linear and quadratic LIV, respectively. Therefore, this is the first proof-of-principles application of profile likelihood method to the analysis of GRB spectral lag data to constrain LIV.
title Constraint on Lorentz Invariance Violation for spectral lag transition in GRB 160625B using profile likelihood
topic High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2411.09248