Fast radio bursts from reconnection in magnetar magnetosphere

Lyubarsky, Yuri

doi:10.48550/arxiv.2001.02007

Cited by 4 publications

(4 citation statements)

References 29 publications

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“…2). The single power law can be expected in a relativistic outflow with internal shocks 6 or colliding magnetized shells 64 over the time of 10 −5 s which is enough to produce the hard X-ray synchrotron photons with particle spectral indices ≥ 1 65,66 . In an alternative scenario of magnetar transient emission 67 , recently applied to FRBs 68 , radio/X-ray flares resemble solar flares.…”

Section: Emission Scenariosmentioning

confidence: 99%

A peculiar hard X-ray counterpart of a Galactic fast radio burst

Ridnaia,

Svinkin,

Frederiks

et al. 2020

Preprint

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Fast radio bursts are bright, millisecond-scale radio flashes of yet unknown physical origin 1 .Recently, their extragalactic nature has been demonstrated 2, 3 , and an increasing number of the sources have been found to repeat 4 . Young, highly magnetized, isolated neutron stars -magnetars -have been suggested as the most promising candidates for fast radio burst progenitors owing to their energetics and high X-ray flaring activity 5, 6 . Here we report the detection with the Konus-Wind detector of a hard X-ray event of April 28, 2020, temporarily coincident with a bright, two-peak radio burst 7, 8 with properties remarkably similar to those of fast radio bursts. The source of the radio burst is located 7 in the direction to the Galactic magnetar SGR 1935+2154, which recently entered an active state. We show that a separation between two peaks of the double-peaked X-ray burst is nearly the same as that of the radio peaks, confirming that the X-ray and radio emission most likely have a common origin. Thus, this is the first simultaneous detection of a fast radio burst from a Galactic magnetar and its high-energy counterpart.The total energy emitted in X-rays in this burst is typical of bright short magnetar bursts, but its spiky light curve and an unusual hardness of the energy spectrum distinguish the April 28 event among multiple 'ordinary' flares detected from SGR 1935+2154 previously. This, and a recent non-detection 9 of radio emission from two typical bright soft bursts 10 from the same magnetar, may imply the existence of a special class of magnetar flares capable of producing fast radio bursts.

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Section: Emission Scenariosmentioning

confidence: 99%

A peculiar hard X-ray counterpart of a Galactic fast radio burst

Ridnaia,

Svinkin,

Frederiks

et al. 2020

Preprint

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“…The first class consists of the "far-away" models where relativistic ejecta from a neutron star (or black hole) dissipates its energy at large distances by interacting with the circum-stellar medium (CSM) and the radio emission is generated by a maser process (Lyubarsky 2014;Waxman 2017;Beloborodov 2017Beloborodov , 2019Metzger et al 2019;Margalit et al 2020a). The second class are the "close-in" models which describe that the coherent processes occur within the magnetosphere of a neutron star (Pen & Connor 2015;Cordes & Wasserman 2016;Lyutikov et al 2016;Kumar et al 2017;Zhang 2017;Lu & Kumar 2018;Yang & Zhang 2018;Kumar & Bošnjak 2020;Lyubarsky 2020). These two general classes of models have very different predictions regarding the FRB temporal and spectral properties, and multiwavelength counterparts.…”

Section: Emission Mechanismmentioning

confidence: 99%

A unified picture of Galactic and cosmological fast radio bursts

Kumar

Zhang³

2020

Preprint

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The discovery of a fast radio burst (FRB) in our galaxy associated with a magnetar (neutron star with strong magnetic field) has provided a critical piece of information to help us finally understand these enigmatic transients. We show that the volumetric rate of Galactic-FRB like events is consistent with the faint end of the cosmological FRB rate, and hence they most likely belong to the same class of transients. The Galactic FRB had an accompanying X-ray burst but many X-ray bursts from the same object had no radio counterpart. Their relative rates suggest that for every FRB there are roughly 10 2 -10 3 X-ray bursts. The radio lightcurve of the galactic FRB had two spikes separated by 30 ms in the 400-800 MHz frequency band. This is an important clue and highly constraining of the class of models where the radio emission is produced outside the light-cylinder of the magnetar. We suggest that magnetic disturbances close to the magnetar surface propagate to a distance of a few tens of neutron star radii where they damp and produce radio emission. The coincident hard X-ray spikes associated with the two FRB pulses seen in this burst and the flux ratio between the two frequency bands can be understood in this scenario. This model provides a unified picture for faint bursts like the Galactic FRB as well as the bright events seen at cosmological distances.

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“…FREE PRECESSION OF A MAGNETAR 2.1. Appearance of a precessing FRB-producing neutron star We focus on a class of scenarios, in which the bursts are powered by giant flares of magnetars (Popov & Postnov 2013;Lyubarsky 2014;Beloborodov , 2019Metzger et al 2019;Margalit et al 2019;Lyubarsky 2020). In these models, the hyper-activity of repeating FRBs results from fast ambipolar diffusion of the magnetic field in the magnetar core, on the timescale ∼ 10 9 s (Beloborodov & Li 2016; Beloborodov 2017).…”

Section: Introductionmentioning

confidence: 99%

Precessing flaring magnetar as a source of repeating FRB 180916.J0158+65

Levin,

Beloborodov,

Bransgrove

2020

Preprint

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Recently, CHIME detected periodicity in the bursting rate of the repeating FRB 180916.J0158+65. In a popular class of models, the fast radio bursts (FRBs) are created by giant magnetic flares of a hyper-active magnetar driven by fast ambipolar diffusion in the core. We point out that in this scenario the magnetar is expected to precess freely with a period of hours to weeks. The internal magnetic field B ∼ 10 16 G deforms the star, and magnetic flares induce sudden changes in magnetic stresses. The resulting torques and displacements of the principal axes of inertia are capable of pumping a significant amplitude of precession. The anisotropy of the flaring FRB activity, combined with precession, implies a strong periodic modulation of the visible bursting rate. The ultra-strong field invoked in the magnetar model provides: (1) energy for the frequent giant flares, (2) the high rate of ambipolar diffusion, releasing the magnetic energy on the timescale ∼ 10 9 s, (3) the core temperature T ≈ 10 9 K, likely above the critical temperature for neutron superfluidity, (4) strong magnetospheric torques, which efficiently spin down the star, and (5) deformation with ellipticity > ∼ 10 −6 , much greater than the rotational deformation. These conditions result in a precession with negligible viscous damping, and can explain the observed 16-day period in FRB 180916.J0158+65. The increase of precession period due to the magnetar spindown should become measurable in the near future. 1 We also refer readers to a recent preprint by Lyutikov et al. (2020) which explores a scenario with a companion. These authors note that geodetic precession is unlikely to produce the required periodicity. We emphasize that in our model the precession is free

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Fast radio bursts from reconnection in magnetar magnetosphere

Cited by 4 publications

References 29 publications

A peculiar hard X-ray counterpart of a Galactic fast radio burst

A peculiar hard X-ray counterpart of a Galactic fast radio burst

A unified picture of Galactic and cosmological fast radio bursts

Precessing flaring magnetar as a source of repeating FRB 180916.J0158+65

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