High energy emission from pulsars: Outer gap scenario

Hirotani, Kouichi

doi:10.1016/j.asr.2005.05.063

Cited by 7 publications

(4 citation statements)

References 37 publications

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“…In outer magnetospheric vacuum gaps of pulsars, curvature radiation is thought to initiate the pair cascade, limiting the gap growth by supplying charged particles (cf. Cheng et al 1986;Hirotani 2005;Tang et al 2008). The gamma rays produced by the cascade and leaving the pulsar magnetosphere in a confined beam are made responsible for the observed highenergy (HE) and very high energy (VHE) pulsed emission.…”

Section: Introductionmentioning

confidence: 99%

Electron-beam interaction with emission-line clouds in blazars

Wendel

González

Paneque

et al. 2021

A&A

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Context. An electron-positron beam escaping from the magnetospheric vacuum gap of an accreting black hole interacts with recombination-line photons from surrounding gas clouds. Inverse-Compton scattering and subsequent pair production initiate unsaturated electromagnetic cascades exhibiting a characteristic spectral energy distribution. Aims. By modelling the interactions of beam electrons (positrons) with hydrogen and helium recombination-line photons, we seek to describe the spectral signature of beam-driven cascades in the broad emission-line region of blazar jets. Methods. Employing coupled kinetic equations for electrons (positrons) and photons including an escape term, we numerically obtained their steady-state distributions and the escaping photon spectrum. Results. We find that cascade emission resulting from beam interactions can produce a narrow spectral feature at TeV energies. Indications of such an intermittent feature, which defies an explanation in the standard shock-in-jet scenario, have been found at ≈ 4σ confidence level at an energy of ≈ 3 TeV in the spectrum of the blazar Mrk 501. Conclusions. The energetic requirements for explaining the intermittent 3 TeV bump with the beam-interaction model are plausible: Gap discharges that lead to multi-TeV beam electrons (positrons) carrying ≈ 0.1% of the Blandford-Znajek luminosity, which interact with recombination-line photons from gas clouds that reprocess ≈ 1% of the similar accretion luminosity are required.

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Section: Introductionmentioning

confidence: 99%

Electron-beam interaction with emission-line clouds in blazars

Wendel

González

Paneque

et al. 2021

A&A

View full text Add to dashboard Cite

show abstract

“…In outer magnetospheric vacuum gaps of pulsars, curvature radiation is thought to initiate the pair cascade, limiting the gap growth by supplying charged particles (cf. Cheng et al 1986;Hirotani 2005;Tang et al 2008). The gamma rays produced by the cascade and leaving the pulsar magnetosphere in a confined beam are made responsible for the observed high-energy (HE) and very high energy (VHE) pulsed emission.…”

Section: Introductionmentioning

confidence: 99%

Electron-beam interaction with emission-line clouds in blazars

Wendel,

González,

Paneque

et al. 2020

Preprint

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Context. An electron-positron beam escaping from the magnetospheric vacuum gap of an accreting black hole interacts with recombinationline photons from surrounding gas clouds. Inverse-Compton scattering and subsequent pair production initiate unsaturated electromagnetic cascades exhibiting a characteristic spectral energy distribution. Aims. By modelling the interactions of beam electrons (positrons) with hydrogen and helium recombination-line photons, we seek to describe the spectral signature of beam-driven cascades in the broad emission-line region of blazar jets. Methods. Employing coupled kinetic equations for electrons (positrons) and photons including an escape term, we numerically obtain their steady-state distributions and the escaping photon spectrum. Results. We find that cascade emission resulting from beam interactions can produce a narrow spectral feature at TeV energies. Indications of such an intermittent feature, which defies an explanation in the standard shock-in-jet scenario, have been found at ≈ 4 σ confidence level at an energy of ≈ 3 TeV in the spectrum of the blazar Mrk 501. Conclusions. The energetic requirements for explaining the intermittent 3 TeV bump with the beam-interaction model are plausible: Gap discharges that lead to multi-TeV beam electrons (positrons) carrying ≈ 0.1 % of the Blandford-Znajek luminosity, which interact with recombination-line photons from gas clouds that reprocess ≈ 1 % of the similar accretion luminosity are required.

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“…The most crucial issue about this high-energy emission of pulsars is the location of the acceleration region in the magnetosphere: is it in the outer gap (e.g., Ref. [98,99]; review by [100]) or in the polar cap (e.g., Ref. [101]; review by [102]).…”

mentioning

confidence: 99%

Very-High Energy Gamma Astrophysics

De Angelis,

Mansutti,

Persic

2007

Preprint

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High-energy photons are a powerful probe for astrophysics and for fundamental physics under extreme conditions. During the recent years, our knowledge of the most violent phenomena in the Universe has impressively progressed thanks to the advent of new detectors for high-energy γ-rays. Observation of γ-rays gives an exciting view of the high-energy universe thanks to satellite-based telescopes (AGILE, GLAST) and to ground-based detectors like the Cherenkov telescopes (H.E.S.S. and MAGIC in particular), which recently discovered more than 60 new very-high-energy sources. The progress achieved with the last generation of Cherenkov telescopes is comparable to the one drawn by EGRET with respect to the previous γ-ray satellite detectors. This article reviews the present status of high-energy gamma astrophysics, with emphasis on the recent results and on the experimental developments.

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High energy emission from pulsars: Outer gap scenario

Cited by 7 publications

References 37 publications

Electron-beam interaction with emission-line clouds in blazars

Electron-beam interaction with emission-line clouds in blazars

Electron-beam interaction with emission-line clouds in blazars

Very-High Energy Gamma Astrophysics

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