Coherent inverse Compton scattering by bunches in fast radio bursts

Zhang, Bing

doi:10.48550/arxiv.2111.06571

Cited by 3 publications

(12 citation statements)

References 55 publications

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“…Highly circle-polarized emission is the natural consequence of the coherent outcome waves from particles, with some spatial distributions, i.e., bunches. The mechanisms by invoking charged bunches can also interpret the narrow band spectrum and downwards drifting structure of repeating FRBs [35][36][37]55].…”

Section: Conclusion and Discussionmentioning

confidence: 98%

“…Generally, trajectories of charged particles are tracked by magnetic field lines, because of the rapid dump of vertical momentum perpendicular to the field line. These charged bunches stream outward along the magnetic field lines, emitting FRB waves via CR [36,54,[62][63][64][65] or ICS by a low-frequency electromagnetic wave [55], as shown in Figure 1.…”

Section: Intrinsic Mechanismmentioning

confidence: 99%

“…This is not surprising since both ways of coherent superposition are relevant to a bunch of charged particles but only different in radiative mechanism (either CR or ICS), and thus circularly polarized emission can naturally appear via adding up so many linearly polarized waves with different phases and electric vectors produced by every particles. Recently, Zhang [55] proposed a family of model invoking coherent ICS of bunched particles that may operate within or just outside of the magnetosphere of a flaring magnetar.…”

Section: Coherent Inverse Compton Scatteringmentioning

confidence: 99%

“…In this paper, we focus on demonstrating the polarization properties within the framework of a generic pulsar-like model by invoking charged bunches in magnetosphere. FRB emissions by the bunches, could be via either coherent CR [36,54] or coherent inverse Compton scattering (ICS) [55]. We discuss the two intrinsic mechanisms in Section 2.…”

Section: Introductionmentioning

confidence: 99%

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Repeating Fast Radio Burst: Coherent Circular Polarization By Bunches

Wang¹,

Jiang²,

Lu³

et al. 2021

Preprint

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Fast radio bursts (FRBs) are millisecond-duration signals, to be highly dispersed at distant galaxies, the physical origin of which is still challenging. Coherent curvature emission by bunches powered, e.g., by starquakes, has already been proposed for repeating FRBs, with a friendly nature of understanding the narrowband radiation exhibiting time-frequency drifting. Recently, a highly active FRB source, FRB 20201124A, was reported to enter a newly active episode and emit at least some highly circle-polarized bursts. We revisit the polarized FRB emission here, investigating especially the production mechanisms of a high circular polarization by deriving intrinsic and propagation effects. The intrinsic mechanisms by invoking charged bunches are approached in two scenarios of coherence: curvature radiation (CR) and inverse Compton scattering (ICS), and consequently, a high circular polarization could naturally be explained by the coherent summation of outcome waves, generated or scattered by bunches, with different phases and electric vectors. Cyclotron resonance can result in an absorption of R-mode photons at lower altitude region of magnetosphere, and an FRB should then be emitted from a higher region if the waves are of strong linear polarization. Circularly polarized components could be produced from Faraday conversion exhibiting a 𝜆 3 -oscillation, but the average circular polarization fraction depends only on the income wave, indicating a possibility of highly circle-polarized income wave. The analysis could be welcome if extremely high (e.g., almost 100%) circular polarization from repeating FRBs would be detected in the future. The production of a bulk of energetic bunches in pulsar-like magnetosphere is discussed finally, which is relevant to the nature of FRB central engine.

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Section: Conclusion and Discussionmentioning

confidence: 98%

Section: Intrinsic Mechanismmentioning

confidence: 99%

Section: Coherent Inverse Compton Scatteringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Repeating Fast Radio Burst: Coherent Circular Polarization By Bunches

Wang¹,

Jiang²,

Lu³

et al. 2021

Preprint

View full text Add to dashboard Cite

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“…There have been tens of possible mechanisms for pulsar radio emission, and it has been proposed that some of them (e.g., free electron laser mechanism) can be applied to FRBs and reach high brightness temperature (Lyutikov 2021b). Interestingly, Zhang (2021) recently suggested that the coherent inverse Compton scattering could be a promising mechanism, in which the bunch formation problem can be largely relieved due to enhanced emission power of a single electron. Plenty of works need to be done to figure out FRB radiation mechanism, and the T −F ν relation could provide some hints for future studies.…”

Section: Discussionmentioning

confidence: 99%

New Insights into the Criteria of Fast Radio Burst in the Light of FRB 20121102A

Xiao,

Dai

2021

Preprint

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The total event number of fast radio bursts (FRBs) is accumulating rapidly with the improvement of existing radio telescopes and the completion of new facilities. Especially, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) Collaboration has just reported more than one thousand bursts in a short observing period of 47 days (Li et al. 2021). The interesting bimodal distribution in their work motivates us to revisit the definition of FRBs. In this work, we ascribe the bimodal distribution to two physical kinds of radio bursts, which may have different radiation mechanisms. We propose to use brightness temperature to separate two subtypes. For FRB 20121102A, the critical brightness temperature is T B,cri ≃ 10 33 K. Bursts with T B ≥ T B,cri are denoted as "classical" FRBs, and further we find a tight pulse width-fluence relation (T ∝ F ν 0.306 ) for them. On the contrary, the other bursts are considered as "atypical" bursts that may originate from a different physical process. We suggest that for each FRB event, a similar dividing line should exist but T B,cri is not necessarily the same. Its exact value depends on FRB radiation mechanism and properties of the source.

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The plasma suppression effect can be ignored in realistic FRB models invoking bunched coherent radio emission

Qu¹,

Zhang²

2021

Preprint

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One widely discussed mechanism to produce highly coherent radio emission of fast radio bursts (FRBs) is coherent emission by bunches, either via curvature radiation or inverse Compton scattering (ICS). It has been suggested that the plasma oscillation effect can significantly suppress coherent emission by bunches, so that the bunching mechanism may not be the dominant mechanism for FRBs. We critically examine two physical conditions for significant plasma suppression and argue that the suppression effect is not important for the coherent ICS mechanism. A suppression factor for curvature radiation cur is possible if the giant bunch charge is surrounded by a high density plasma so that ≫ is satisfied, and if the electric field strength along the magnetic field lines ( ) in the emission region is not large enough to separate the surrounding plasma. However, even under these conditions, the derived cur is about 6 orders of magnitude greater than that derived in previous work, so that the suppression effect is not as significant as predicted before. We conclude that bunched coherent curvature radiation is still a plausible mechanism to power FRB emission, even though a suppression factor of the order cur ∼ 10 −3 should be considered in future modeling.

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Coherent inverse Compton scattering by bunches in fast radio bursts

Cited by 3 publications

References 55 publications

Repeating Fast Radio Burst: Coherent Circular Polarization By Bunches

Repeating Fast Radio Burst: Coherent Circular Polarization By Bunches

New Insights into the Criteria of Fast Radio Burst in the Light of FRB 20121102A

The plasma suppression effect can be ignored in realistic FRB models invoking bunched coherent radio emission

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