Year: 2026
Type: preprint
Abstract: Hard X-rays in persistent magnetar emission originate from radiative processes in pair-loaded magnetospheric plasma, yet self-consistent kinetic simulations of such radiation-rich systems remain limited. We perform 1D particle-in-cell simulations of pair creation mediated by resonant inverse Compton scattering (RICS) along isolated field lines in twisted magnetospheres, capturing particle acceleration and radiative drag from first principles. The drag force, which strongly depends on the particle Lorentz factor and location, plays a key role in the magnetospheric circuit. Strong RICS drag impedes the flow of electrons and positrons, particularly along extended field lines. Nevertheless, the plasma sustains the circuit by self-organizing into a single accelerating gap near the star in one hemisphere. The accelerated plasma flow from the gap becomes loaded with copious electron-positron pairs in extended RICS zones, and also carries ions extracted from the star and accelerated in the gap. When radiative drag stops the pair-loaded flow at the magnetic equator, the ion component transfers momentum through streaming instabilities, delivering a small lepton population into the opposite hemisphere and sustaining the circuit. The gap confined to a single (anode) hemisphere implies asymmetric hard X-ray production, possibly detectable in phase-resolved magnetar spectra.
Source: arXiv (Cornell University)
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1047285063, G1513662220, G1587926220, Collaborative Research: WoU-MMA: Multimessenger Plasma Physics Center (MPPC), WoU-MMA: Generation of Ultrastrong Magnetic Fields in Nascent Neutron Stars, G4218673142, Plasma Dynamics in Radiation-Rich Magnetar Magnetospheres: Implications for Multi-Wavelength Emission, Global kinetic modeling of the intrabinary shock in spider pulsars, G5817347332, Kavli Institute for Theoretical Physics, G8520910697
OpenAlex ID: W7213527058