Lorentz invariance violation search with flaring active galactic nuclei observations of the first Large-Sized Telescope of CTAO

Cyann Plard; Sami Caroff; the CTAO-LST project

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arXiv · 2604.10236

Lorentz invariance violation search with flaring active galactic nuclei observations of the first Large-Sized Telescope of CTAO

Cyann Plard·Sami Caroff·the CTAO-LST project

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Abstract

The rapid variability observed in very-high-energy (VHE) sources-such as pulsars, gamma-ray bursts (GRBs), and flares from active galactic nuclei (AGN)-can be used to detect or constrain a potential violation of Lorentz invariance (LIV). These effects can be investigated by measuring time lags in the arrival of VHE photons. However, an important source of uncertainty arises from intrinsic processes within the sources themselves that may induce photon delays unrelated to LIV. To address this challenge, we aim to combine observations of different sources, located at different redshifts. In this study, we present the results of a standardized analysis applied to all AGN observations conducted by the first Large-Sized Telescope of the upcoming Cherenkov Telescope Array Observatory. Our analysis includes a systematic search for intra-night variability in archival data from nights with significant excess detections for target candidates. By combining these observations, we derive constraints on the characteristic energy scales at which LIV deterministic or stochastic effects are expected to manifest.

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Cyann Plard, Sami Caroff, the CTAO-LST project. 2026-04-11. Lorentz invariance violation search with flaring active galactic nuclei observations of the first Large-Sized Telescope of CTAO. https://arxiv.org/abs/2604.10236

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