The FRB-SGR Connection

Katz, J. I.

doi:10.48550/arxiv.2006.03468

Cited by 7 publications

(7 citation statements)

References 16 publications

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“…It is well established that the X-ray emission originates from the magnetosphere of a magnetar 137 . Therefore the pulsar-like mechanism is favoured for FRB 200428, by Occam's Razor 79,125,139 . A GRB-like model interprets the observed X-rays as the superposition of magnetospheric and shock emissions, with the latter component consistent with the relatively hard spectra during the two lightcurve peaks 138 .…”

Section: Box 1 Comparison Of Pulsar-like Models and Grb-like Modelsmentioning

confidence: 99%

The physical mechanisms of fast radio bursts

Zhang

2020

Nature

289

189

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Fast radio bursts are mysterious millisecond-duration transients prevalent in the radio sky. Rapid accumulation of data in recent years has facilitated an understanding of the underlying physical mechanisms of these events. Knowledge gained from the neighboring fields of gamma-ray bursts and radio pulsars also offered insight. Here I review developments in this fast-moving field.Two generic categories of radiation model invoking either magnetospheres of compact objects (neutron stars or black holes) or relativistic shocks launched from such objects have been much debated. The recent detection of a Galactic fast radio burst in association with a soft gamma-ray repeater suggests that magnetar engines can produce at least some, and probably all, fast radio bursts. Other engines that could produce fast radio bursts are not required, but are also not impossible. On 24 July, 2001, a bright, dispersed radio pulse reached the Parkes 64-m telescope in Australia. The recorded signal remained unnoticed until Duncan Lorimer and his collaborators discovered it (now known as the fast radio burst FRB 010724) several years later and published the results in Science 1. For some time, some astronomers were not convinced that this so-called "Lorimer burst" was a genuine type of astrophysical event, until four more events were reported in 2013 (ref. 2). The field then enjoyed a rapid boost from both observational and theoretical fronts. With the identification of the microwave-oven-origin of some artificial bursts known as "perytons", the astrophysical origin of the bona fide bursts was finally established 3. This was followed by the detection of the first repeating source, known as FRB 121102 (ref. 4) and its localization in a dwarf star forming galaxy at redshift z = 0.19(refs. 5-7), establishing the extragalactic/cosmological origin (in contrast to the Galactic origin 8) of these events. Numerous theoretical models have been proposed to interpret these mysterious events 9. These have been driven by observations and groundbreaking results from numerous radio observatories: Parkes, Arecibo, Green Bank Telescope, the 1

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Section: Box 1 Comparison Of Pulsar-like Models and Grb-like Modelsmentioning

confidence: 99%

The physical mechanisms of fast radio bursts

Zhang

2020

Nature

289

189

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“…The source of FRB 200428 shows an analogously anomalous distribution of burst strengths, with FRB 200428 orders of magnitude more intense than subsequent bursts from this source. This may be explained by the collimation of radiation emitted by relativistic charges into a narrow beam that may jitter or wander in direction (Katz 2020). No such explanation is apparent for the distribution of RM among FRB sources.…”

Section: Discussionmentioning

confidence: 99%

The Environment of FRB 121102 and Possible Relation to SGR/PSR J1745-2900

Katz

2020

Preprint

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Variations of the dispersion (DM) and rotation (RM) measures of FRB 121102 indicate magnetic fields ∼ 3-17 mG in the dispersing plasma. The electron density may be ∼ 10 4 cm −3 . The observed time scales ∼ 1 year constrain the size of the plasma cloud. Increasing DM excludes simple models involving an expanding supernova remnant, and the non-zero RM excludes spherical symmetry. The varying DM and RM may be attributable to the motion of plasma into or out of the line of sight to or changing electron density within slower-moving plasma. The extraordinarily large RM of FRB 121102 implies an environment, and possibly also a formation process and source, qualitatively different from those of other FRB. The comparable and comparably varying RM of SGR/PSR J1745−2900 suggests it as a FRB candidate. An appendix discusses the age of FRB 121102 in the context of a "Copernican Principle".

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“…It is often assumed that the GHz coherent emission is generated by coherent charge bunches through, e.g., curvature or synchrotron maser processes. In the case of curvature radiation, the emission is often thought to be triggered by magnetic reconnection in the vicinity of NS (e.g., Katz 2016;Kumar et al 2017;Ghisellini & Locatelli 2018;Lu & Kumar 2018;Yang & Zhang 2018;Katz 2020;Lu et al 2020). In the case of the synchrotron maser emission, the emission occurs at relativistic shocks propagating in the pre-existing media, such as nebula (Lyubarsky 2014;Murase et al 2016;Waxman 2017), steady magnetar wind (Beloborodov 2017), or past flare-driven ejecta (Metzger et al 2019;Beloborodov 2020;Margalit et al 2020;Yuan et al 2020;Yu et al 2020).…”

Section: Plasma Cutoff Frequencymentioning

confidence: 99%

Multi-Wavelength Constraints on the Outflow Properties of the Extremely Bright Millisecond Radio Bursts from the Galactic Magnetar SGR 1935+2154

Yamasaki,

Kashiyama,

Murase

2020

Preprint

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Recently, a bright coherent radio burst with millisecond duration, reminiscent of cosmological fast radio bursts (FRBs), was co-detected with an anomalously-hard X-ray burst from a Galactic magnetar SGR 1935+2154. We investigate the possibility that the event was triggered by a deposition of a magnetic energy in a localized region of the magnetosphere, thereby producing a so-called trapped fireball (FB) and simultaneously launching relativistic outflows. We show that the thermal component of the X-ray burst spectrum is consistent with a trapped FB with an average temperature of a few hundred keV and a size of ∼ 10 5 cm. Meanwhile, the non-thermal component of the X-ray burst and the coherent radio burst may arise from relativistic outflows. We calculate the dynamical evolution of the outflow, launched with an energy budget ∼ 10 39 -10 40 erg comparable to that of the trapped FB, for a variety of baryon load η and initial magnetization σ 0 parameters. If both the hard X-ray and radio bursts are produced by the energy dissipation of the outflow, the properties can be constrained by the conditions for photon escape and the intrinsic timing offset of 10 ms among the radio and X-ray burst spikes. We show that the hard X-ray bursts need to be generated at r X 10 8 cm from the stellar surface, irrespective of the emission mechanism. Particularly in the case of shock dissipation, the outflow should accelerate up to a Lorentz factor of Γ 10 3 by the time it reaches the outer edge of the magnetosphere and the shock dissipation should take place at 10 12 cm r radio,X 10 14 cm. In this case, extremely clean (η 10 4 ) and/or highly magnetized (σ 0 10 3 ) outflows are implied, which may be consistent with the rarity of this phenomenon.

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The FRB-SGR Connection

Cited by 7 publications

References 16 publications

The physical mechanisms of fast radio bursts

The physical mechanisms of fast radio bursts

The Environment of FRB 121102 and Possible Relation to SGR/PSR J1745-2900

Multi-Wavelength Constraints on the Outflow Properties of the Extremely Bright Millisecond Radio Bursts from the Galactic Magnetar SGR 1935+2154

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