The synchrotron maser emission from relativistic shocks in Fast Radio Bursts: 1D PIC simulations of cold pair plasmas

Abstract

The emission process of Fast Radio Bursts (FRBs) remains unknown. We investigate whether the synchrotron maser emission from relativistic shocks in a magnetar wind can explain the observed FRB properties. We perform particle-in-cell (PIC) simulations of perpendicular shocks in cold pair plasmas, checking our results for consistency among three PIC codes. We confirm that a linearly polarized X-mode wave is self-consistently generated by the shock and propagates back upstream as a precursor wave. We find that at magnetizations $\sigma \gtrsim 1$ (i.e., ratio of Poynting flux to particle energy flux of the pre-shock flow) the shock converts a fraction $f_{\xi }^{\prime }\approx 7\times 10^{-4}/{\sigma }^2$ of the total incoming energy into the precursor wave, as measured in the shock frame. The wave spectrum is narrow-band (fractional width $\lesssim 1-3$), with apparent but not dominant line-like features as many resonances concurrently contribute. The peak frequency in the pre-shock (observer) frame is ${\omega }_{\mathrm{peak}}^{\prime \prime }\approx 3{\gamma }_{s|u}{\omega }_{\mathrm{p}}$, where ${\gamma }_{s|u}$ is the shock Lorentz factor in the upstream frame and ${\omega }_{\mathrm{p}}$ the plasma frequency. At $\sigma \gtrsim 1$, where our estimated ${\omega }_{\mathrm{peak}}^{\prime \prime }$ differs from previous works, the shock structure presents two solitons separated by a cavity, and the peak frequency corresponds to an eigenmode of the cavity. Our results provide physically-grounded inputs for FRB emission models within the magnetar scenario.

MNRAS in press. 19 pages, 15 figures, 2 appendices. Added appendix B that compares 1d, 2d, and 3d results

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Cited by in corpus (10)

• Fast radio bursts as synchrotron maser emission from decelerating relativistic blast waves
• Implications of a "Fast Radio Burst" from a Galactic Magnetar
• The Physics of Fast Radio Bursts
• Plasmoid ejection by Alfvén waves and the fast radio bursts from SGR 1935+2154
• What does FRB light-curve variability tell us about the emission mechanism?
• The synchrotron maser emission from relativistic magnetized shocks: Dependence on the pre-shock temperature
• Multiwavelength observations of Fast Radio Bursts
• Mildly relativistic magnetized shocks in electron-ion plasmas -- II. Particle acceleration and heating
• Mildly relativistic magnetized shocks in electron-ion plasmas I. Electromagnetic shock structure
• Emission Mechanisms of Fast Radio Bursts