2026/05/16 by Gabriel A. Porto, Jonas P. Pereira, Eduardo Bittencourt +2 · 1 citation
Physics and Astronomy · #Pulsars and Gravitational Waves Research #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae
paper · pdf · doi:10.3847/1538-4357/ae8017
Abstract Magnetars are among the most extreme laboratories in the Universe, harboring surface magnetic fields reaching 10 15 G. At these supercritical scales, Maxwell’s linear electrodynamics is superseded by nonlinear electrodynamics (NLED). While vacuum birefringence has provided initial observational evidence for these effects, its broader impact on photon propagation remains largely unexplored. In this work, we demonstrate that NLED significantly alters photon propagation in the vicinity of magnetars, making light deviate from standard null geodesics. We estimate that neglecting these corrections leads to relative errors of approximately 10% in stellar radii inferred by means of ray-tracing techniques. Furthermore, we find that NLED induces a systematic minimal travel-time delay of approximately 350 ns, a value that already far exceeds the 100 ns temporal resolution of missions like NICER. These results are critical for the interpretation of X-ray pulse profiles from current and future observatories, such as eXTP, which rely on high-precision light-bending and timing models to determine neutron-star masses and radii. Finally, our results underscore the role of magnetars as a vital window into the physics of superdense matter and supercritical fields, and we briefly highlight other astrophysical observables—such as glitches and anti-glitches—that may be affected by NLED.