Study Proposes Mechanism for Fast Radio Bursts from Collapsing Waves in Magnetar Plasma

A new preprint submitted to arXiv proposes that Fast Radio Bursts can be generated by the collapse of macroscopic X-mode waves in the highly magnetized pair plasma surrounding magnetars — strongly magnetized neutron stars. The authors demonstrate analytically that nonlinear long-wavelength X-modes experience severe spatial steepening driven by modifications to the refractive index and strong ponderomotive forces, ultimately collapsing into highly localized, short-wavelength singular pulses. This collapse occurs only within a narrow parameter window where the fluctuating magnetic field component exceeds the background guide field and the plasma is near the current starvation regime, conditions naturally met in magnetar environments. The resulting electromagnetic energy, initially distributed over large spatial scales, is rapidly concentrated into these compact pulses — identified as FRBs. The model predicts a red electromagnetic spectrum scaling as E_k ∝ k⁻² and an unusually hard particle energy distribution f(γ) ∝ γ⁰, both potentially testable signatures. The authors also note that the highest-energy particles produced during collapse could generate short high-energy bursts, suggesting a possible multi-messenger connection. The work is theoretical and computational, with supporting simulation videos provided as supplementary material.