Pair echo model of CTAO/LST-1 signal from GRB 221009A
Abstract
Interactions of very-high energy gamma-rays during their propagation through the intergalactic medium result in a delayed secondary ``pair echo'' signal. Detection of such pair echo can be used for measurements of intergalactic magnetic fields (IGMF) in the voids of the Large Scale Structure of the Universe. We notice that a combination of data of LHAASO and CTAO/LST-1 telescopes on the gamma-ray burst GRB 221009A is consistent with the pair echo model. The LST-1 measurement of the source signal 1.33 days after the burst can be interpreted as the pair echo produced by very-high-energy gamma-rays propagating through intergalactic medium with magnetic field of the strength log(B/G)=-16.2+/- 0.7, if its correlation length lambda_B is larger than 20 kpc. If the field correlation length is shorter than 20 kpc, the field strength estimate is modified upwards by a square root of (20 kpc / lambda_B). In the specific case of short correlation length IGMF that is relic from cosmological phase transitions, the pair echo model of the LST-1 signal implies the field strength in the 1e-14-1e-12 G range. Such magnetic field parameters are consistent with all known constraints on IGMF, including the lower bounds from gamma-ray observations of active galactic nuclei.
Related
- ALMA - CTAO synergies
- Reassessing the contribution of long-GRB high-energy afterglows to the isotropic gamma-ray background after GRB 221009A
- Unsupervised domain adaptation for multitask image analysis in realistic context with extreme label shift; Application to the CTAO first large sized telescope
- JWST's Dusty Blue BOAT -- GRB 221009A
- JWST’s Dusty Blue BOAT - GRB 221009A
BibTeX
@misc{neronov2026pair,
title = {{Pair echo model of CTAO/LST-1 signal from GRB 221009A}},
author = {Andrii Neronov and Ievgen Vovk and Teneman Keita and Davide Miceli},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.06633},
eprint = {2610.06633},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05829740v1},
}
RIS
TY - UNPB
TI - Pair echo model of CTAO/LST-1 signal from GRB 221009A
AU - Andrii Neronov
AU - Ievgen Vovk
AU - Teneman Keita
AU - Davide Miceli
PY - 2026
DA - 2026/10/05
PB - HAL
DO - 10.48550/arxiv.2610.06633
UR - https://hal.science/hal-05829740v1
AB - Interactions of very-high energy gamma-rays during their propagation through the intergalactic medium result in a delayed secondary ``pair echo'' signal. Detection of such pair echo can be used for measurements of intergalactic magnetic fields (IGMF) in the voids of the Large Scale Structure of the Universe. We notice that a combination of data of LHAASO and CTAO/LST-1 telescopes on the gamma-ray burst GRB 221009A is consistent with the pair echo model. The LST-1 measurement of the source signal 1.33 days after the burst can be interpreted as the pair echo produced by very-high-energy gamma-rays propagating through intergalactic medium with magnetic field of the strength log(B/G)=-16.2+/- 0.7, if its correlation length lambda_B is larger than 20 kpc. If the field correlation length is shorter than 20 kpc, the field strength estimate is modified upwards by a square root of (20 kpc / lambda_B). In the specific case of short correlation length IGMF that is relic from cosmological phase transitions, the pair echo model of the LST-1 signal implies the field strength in the 1e-14-1e-12 G range. Such magnetic field parameters are consistent with all known constraints on IGMF, including the lower bounds from gamma-ray observations of active galactic nuclei.
ER -