2026/02/28 by Koushik Chatterjee, Alexander Philippov, Andrei M. Beloborodov +3
Physics and Astronomy · #Astrophysical Phenomena and Observations #Current sheet #Flare #Gamma-ray bursts and supernovae #Magnetar #Magnetic field #Magnetic reconnection #Magnetohydrodynamic drive #Magnetohydrodynamics #Plasmoid #Pulsars and Gravitational Waves Research #astro-ph.HE
paper · pdf · doi:10.3847/2041-8213/ae8997
published as The Astrophysical Journal Letters, Volume 1006, Issue 2, id.L45, 12 pp., August 2026 · ApJL accepted version
openalex publication_date 2026/07/24 · openalex created_date 2026/07/25 · openalex updated_date 2026/07/25 · arxiv created 2026/08/03 · arxiv updated 2026/08/05
Abstract Gradual crustal deformation can generate strongly twisted magnetic fields around magnetars, potentially triggering giant flares with total energies exceeding 10 44 erg. In this letter, we present the first relativistic magnetohydrodynamic simulation of a surface shear-driven magnetar eruption, capturing reconnection-driven plasma heating, the ejection of relativistically hot plasma, and the formation of a hot fireball confined within the inner magnetosphere. We find that magnetic reconnection in the equatorial current sheet launches a hot trailing outflow capable of powering the initial spike observed in giant flares, while simultaneously leaving behind a thermally stratified fireball with sufficient thermal energy to produce the pulsating, decaying tail. Together, these features provide a self-consistent physical framework for understanding the observed energetics of magnetar giant flares. The eruption also expels a magnetically dominated giant plasmoid carrying up to ∼9% of the magnetosphere’s total magnetic energy. Furthermore, our simulation demonstrates how the plasmoid drives the formation of a blast wave—an important ingredient in models linking magnetar eruptions to fast radio bursts.