2008/02/19 by Christopher Thompson · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Atomic physics #Computational physics #Electron #Field line #Gamma-ray bursts and supernovae #Magnetar #Magnetic field #Magnetosphere #Nuclear physics #Pair production #Physics #Positron #Positronium #Pulsars and Gravitational Waves Research #Quantum electrodynamics #Quantum mechanics #astro-ph
paper · pdf · doi:10.1086/592263
25 pages, submitted to the Astrophysical Journal
arxiv created 2008/02/19 · openalex publication_date 2008/11/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We first examine the QED processes that create electron-positron pairs in magnetic fields approaching and exceeding 10 14 G. The formation of free and bound pairs is addressed, and the importance of positronium dissociation by thermal X-rays is noted. We calculate the collision cross section between an X-ray and a gamma ray, and point out a resonance in the cross section when the gamma ray is close to the threshold for pair conversion. We then show how the pair creation rate in the open-field circuit and the outer magnetosphere can be strongly enhanced by current-driven instabilities near the light cylinder. A cascade develops when the current has a strong fluctuating component. We examine the mechanism of particle heating and show that a high rate of pair creation can be sustained close to the star, but only if the spin period is shorter than several seconds. The dissipation rate in this turbulent state can easily accommodate the observed radio output of the transient radio-emitting magnetars and even their infrared emission. Finally, we outline how a very high rate of pair creation on the open magnetic field lines can help to stabilize a static twist in the closed magnetosphere and to regulate the loss of magnetic helicity by reconnection at the light cylinder.