2025/09/19 by Ténéman Keita, Keita, Ténéman, R. Bélmont +3
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · doi:10.48550/arxiv.2509.16092
openalex publication_date 2025/09/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The InterGalactic Magnetic Field (IGMF), which could permeate the cosmic voids but was never detected so far, is considered a relic of the early Universe. Constraints on its strength B can be derived from its influence on time-delayed very-high-energy photons from Gamma-Ray Bursts (GRBs) in the electromagnetic cascades along their path to the Earth. The present lower limit achieved on its intensity is 10-18 G. In this work, we simulate data from the Cherenkov Telescope Array Observatory (CTAO), accounting for realistic observational constraints, and we apply a joint spectral and temporal fit to characterise the IGMF. GRBs 190114C and 221009A are used as test cases to assess the sensitivity of CTAO. They demonstrate that a broad range of IGMF strengths can be probed with a lower bound as high as 10-15 G. Notably, we show that observations by the CTAO first large telescope, LST-1, already allow us to exclude field strengths up to 3× 10-17 G.