2026/07/22 by K. Abe, S. Abe, J. Abhir +358
Physics and Astronomy · #astro-ph.HE
paper · pdf · doi:10.1088/1538-3873/ae8a7e
published as Publications of the Astronomical Society of the Pacific, Volume 138, Number 8, August 2026 · Published version. Corresponding authors: Andrea Simongini, Juan Jiménez Quiles, Mario Pecimotika, Monica Seglar-Arroyo
arxiv created 2026/08/06 · arxiv updated 2026/08/07
We present very-high-energy gamma-ray observations of two binary black hole merger candidates, GW240615113620 and GW241125010116, performed with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes and the first Large-Sized Telescope of the Cherenkov Telescope Array Observatory's (CTAO LST-1). GW240615113620 was the best localized event of the fourth observing run of the LIGO-Virgo-KAGRA gravitational waves interferometers. GW241125010116 was temporally and spatially coincident with a sub-threshold short-duration burst detected with the Swift-Burst Alert Telescope (BAT), the Swift-X-Ray Telescope (XRT) and the Einstein Probe Follow-up X-ray Telescope (FXT). We observed the two events in stereoscopic mode, taking advantage of the improved sensitivity of joint MAGIC+LST-1 observations. No detection was achieved in the GeV-TeV gamma-ray band for any of the two sources. The unfavourable observing conditions of both events posed a challenge for a standard analysis and therefore a non standard analysis was necessary for both objects. Owing to the small localization area and the association with a GRB-like burst respectively, these events represented an unprecedented opportunity to study in details the electromagnetic emission from binary black holes merger events and, in particular, we discussed two theoretical models that predict a detectable gamma-ray emission and the possible future applications.