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Repeating Fast Radio Bursts from Magnetars with Low Magnetospheric Twist
- Publication Year :
- 2019
-
Abstract
- We analyze the statistics of pulse arrival times in fast radio burst (FRB) 121102 and demonstrate that they are remarkably similar to statistics of magnetar high-energy short bursts. Motivated by this correspondence, we propose that repeating FRBs are generated during short bursts in the closed field line zone of magnetar magnetospheres via a pulsar-like emission mechanism. Crustal slippage events dislocate field line foot points, initiating intense particle acceleration and pair production, giving rise to coherent radio emission similar to that generated near pulsar polar caps. We argue that the energetics of FRB 121102 can be readily accounted for if the efficiency of the conversion of Poynting flux into coherent radio emission is $\sim10^{-4}-10^{-2}$, values consistent with empirical efficiencies of radio emission in pulsars and radio-loud magnetars. Such a mechanism could operate only in magnetars with preexisting low twist of the magnetosphere, so that the charge density in the closed zone is initially insufficient to screen the electric field provoked by the wiggling of magnetic field lines and is low enough to let $\sim 1$ GHz radio emission escape the magnetosphere, which can explain the absence of FRBs from known magnetars. The pair cascades crowd the closed flux tubes with plasma, screening the accelerating electric field, thus limiting the radio pulse duration to $\sim1$ ms. Within the framework of our model, the current dataset of the polarization angle variation in FRB 121102 suggests a magnetic obliquity $\alpha\lesssim40^\circ$ and viewing angle $\zeta$ with respect to the spin axis $\alpha<br />Comment: 11 pages, 4 figures, accepted to ApJ, proofs corrected
- Subjects :
- 010504 meteorology & atmospheric sciences
Field line
Astrophysics::High Energy Astrophysical Phenomena
general [Pulsars]
Magnetosphere
FOS: Physical sciences
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
Magnetar
01 natural sciences
Pulsar
Electric field
0103 physical sciences
Magnetars
Twist
010303 astronomy & astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
0105 earth and related environmental sciences
Physics
High Energy Astrophysical Phenomena (astro-ph.HE)
Fast radio burst
Relativistic processes
Astronomy and Astrophysics
neutron [Stars]
Stars
Magnetic field
magnetic field [Stars]
Astrophysics - Solar and Stellar Astrophysics
Space and Planetary Science
Plasmas
Astrophysics - High Energy Astrophysical Phenomena
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....e46f04f3121576ee6ab248eccef4d83d