Evidence for magnetar precession in X-ray afterglows of gamma-ray bursts

Abstract

Many gamma-ray bursts are followed by periods of extended emission. At least in some cases, the burst afterglow may be powered by a rapidly rotating, highly-magnetised neutron star, which spins down due to electromagnetic and gravitational wave emission. Such a remnant is likely to strongly precess in the early stages of its life, which would lead to modulations in the X-ray luminosity as the triaxiality of the system evolves over time. Using a radiation profile appropriate for a precessing, oblique rotator, we find that Swift-XRT data of a long (080602) and a short (090510) burst matches the model with significantly higher accuracy (mean-square residuals dropping by $\gtrsim 200\%$ in the early stages of the extended emission) than for an orthogonal rotator. We interpret this as evidence for precession in newborn magnetars.

6 pages, 4 figures, 1 table. Accepted for publication in ApJL

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• The evolution of binary neutron star post-merger remnants: a review
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• General-relativistic treatment of tidal $g$-mode resonances in coalescing binaries of neutron stars. II. As triggers for precursor flares of short gamma-ray bursts
• Millisecond Magnetars
• Quasi-periodic oscillations in precursor flares via seismic aftershocks from resonant shattering
• Early Evolution of a Newborn Magnetar with Strong Precession Motion in GRB 180620A
• Gravitational waves from neutron-star mountains
• Premerger phenomena in neutron-star binary coalescences
• Measuring spin in coalescing binaries of neutron stars showing double precursors
• Prospects for Time-Domain and Multi-Messenger Science with eXTP
• Magnetar structure in non-linear electrodynamics with mixed poloidal-toroidal fields
• The evolution effects of radius and moment of inertia for rapidly rotating neutron stars
• Investigating magnetically-induced distortions of neutron stars through gamma-ray burst X-ray plateaus
• Three-stage Collapse of the Long Gamma-Ray Burst from GRB 160625B Prompt Multiwavelength Observations
• Investigating the neutron star physics through observations of several young pulsars in the dipole-field re-emergence scenario
• An analysis of the effect of data processing methods on magnetic propeller models in short GRBs
• Magnetic amplification in premerger neutron stars through resonance-induced magnetorotational instabilities
• Multimessenger signatures of a deformed magnetar in gamma-ray bursts
• A 4.5-s Quasiperiodic Spectral Oscillation in GRB 230307A: Evidence for Free Precession of a Post-Merger Magnetar?