Pulsar giant pulse: Coherent instability near light cylinder

Wei Yang Wang, Ji Guang Lu, Song Bo Zhang, Xue Lei Chen, Rui Luo, Ren Xin Xu

Research output: Contribution to journalArticle

Abstract

Giant pulses (GPs) are extremely bright individual pulses of radio pulsar. In microbursts of Crab pulsar, which is an active GP emitter, zebra-pattern-like spectral structures are observed, which are reminiscent of the “zebra bands” that are observed in type IV solar radio flares. However, band spacing linearly increases with the band center frequency of ∼5-30 GHz. In this study, we propose that the Crab pulsar GP can originate from the coherent instability of plasma near a light cylinder. Further, the growth of coherent instability can be attributed to the resonance observed between the cyclotron-resonant-excited wave and the background plasma oscillation. The particles can be injected into the closed-field line regions owing to magnetic reconnection near a light cylinder. These particles introduce a large amount of free energy that further causes cyclotron-resonant instability, which grows and amplifies radiative waves at frequencies close to the electron cyclotron harmonics that exhibit zebra-pattern-like spectral band structures. Further, these structures can be modulated by the resonance between the cyclotron-resonant-excited wave and the background plasma oscillation. In this scenario, the band structures of the Crab pulsar can be well fitted by a coherent instability model, where the plasma density of a light cylinder should be ~10 13-15 cm −3 , with an estimated gradient of >5:5 × 10 5 cm −4 . This process may be accompanied by high-energy emissions. Similar phenomena are expected to be detected in other types of GP sources that have magnetic fields of ≃ 10 6 G in a light cylinder.

Original languageEnglish
Article number979511
JournalScience China: Physics, Mechanics and Astronomy
Volume62
Issue number7
DOIs
Publication statusPublished - 1 Jul 2019

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pulsars
crabs
cyclotrons
pulses
plasma oscillations
spectral bands
flares
plasma density
emitters
free energy
spacing
harmonics
gradients
causes
magnetic fields
electrons
energy

Cite this

Wang, Wei Yang ; Lu, Ji Guang ; Zhang, Song Bo ; Chen, Xue Lei ; Luo, Rui ; Xu, Ren Xin. / Pulsar giant pulse : Coherent instability near light cylinder. In: Science China: Physics, Mechanics and Astronomy. 2019 ; Vol. 62, No. 7.
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Pulsar giant pulse : Coherent instability near light cylinder. / Wang, Wei Yang; Lu, Ji Guang; Zhang, Song Bo; Chen, Xue Lei; Luo, Rui; Xu, Ren Xin.

In: Science China: Physics, Mechanics and Astronomy, Vol. 62, No. 7, 979511, 01.07.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Pulsar giant pulse

T2 - Coherent instability near light cylinder

AU - Wang, Wei Yang

AU - Lu, Ji Guang

AU - Zhang, Song Bo

AU - Chen, Xue Lei

AU - Luo, Rui

AU - Xu, Ren Xin

PY - 2019/7/1

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N2 - Giant pulses (GPs) are extremely bright individual pulses of radio pulsar. In microbursts of Crab pulsar, which is an active GP emitter, zebra-pattern-like spectral structures are observed, which are reminiscent of the “zebra bands” that are observed in type IV solar radio flares. However, band spacing linearly increases with the band center frequency of ∼5-30 GHz. In this study, we propose that the Crab pulsar GP can originate from the coherent instability of plasma near a light cylinder. Further, the growth of coherent instability can be attributed to the resonance observed between the cyclotron-resonant-excited wave and the background plasma oscillation. The particles can be injected into the closed-field line regions owing to magnetic reconnection near a light cylinder. These particles introduce a large amount of free energy that further causes cyclotron-resonant instability, which grows and amplifies radiative waves at frequencies close to the electron cyclotron harmonics that exhibit zebra-pattern-like spectral band structures. Further, these structures can be modulated by the resonance between the cyclotron-resonant-excited wave and the background plasma oscillation. In this scenario, the band structures of the Crab pulsar can be well fitted by a coherent instability model, where the plasma density of a light cylinder should be ~10 13-15 cm −3 , with an estimated gradient of >5:5 × 10 5 cm −4 . This process may be accompanied by high-energy emissions. Similar phenomena are expected to be detected in other types of GP sources that have magnetic fields of ≃ 10 6 G in a light cylinder.

AB - Giant pulses (GPs) are extremely bright individual pulses of radio pulsar. In microbursts of Crab pulsar, which is an active GP emitter, zebra-pattern-like spectral structures are observed, which are reminiscent of the “zebra bands” that are observed in type IV solar radio flares. However, band spacing linearly increases with the band center frequency of ∼5-30 GHz. In this study, we propose that the Crab pulsar GP can originate from the coherent instability of plasma near a light cylinder. Further, the growth of coherent instability can be attributed to the resonance observed between the cyclotron-resonant-excited wave and the background plasma oscillation. The particles can be injected into the closed-field line regions owing to magnetic reconnection near a light cylinder. These particles introduce a large amount of free energy that further causes cyclotron-resonant instability, which grows and amplifies radiative waves at frequencies close to the electron cyclotron harmonics that exhibit zebra-pattern-like spectral band structures. Further, these structures can be modulated by the resonance between the cyclotron-resonant-excited wave and the background plasma oscillation. In this scenario, the band structures of the Crab pulsar can be well fitted by a coherent instability model, where the plasma density of a light cylinder should be ~10 13-15 cm −3 , with an estimated gradient of >5:5 × 10 5 cm −4 . This process may be accompanied by high-energy emissions. Similar phenomena are expected to be detected in other types of GP sources that have magnetic fields of ≃ 10 6 G in a light cylinder.

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