Turbulent Model of Crab Nebula Radiation

Luo, Yonggang; Lyutikov, Maxim; Temim, Tea; Comisso, Luca

doi:10.3847/1538-4357/ab93c0

Cited by 17 publications

(14 citation statements)

References 93 publications

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“…Three-dimensional relativistic ideal MHD simulations supports the notion of disordering of the magnetic field (Porth et al 2013) which has been argued to account for the slowing of the expansion velocity to match the observations (Tanaka et al 2018) and the comparably small polarization observed at X-rays (Bucciantini et al 2017;Weisskopf et al 1978). In non-ideal MHD plasma flows, dissipation of magnetic fields would need to be considered as well (Tanaka et al 2018;Luo et al 2020). In this type of extension of the pulsar wind nebula scenario, several of the fundamental short comings of the toroidal field model of the Crab Nebula (Kennel & Coroniti 1984b) can be overcome as argued by Luo et al (2020).…”

Section: Magnetic Field Structurementioning

confidence: 56%

“…In non-ideal MHD plasma flows, dissipation of magnetic fields would need to be considered as well (Tanaka et al 2018;Luo et al 2020). In this type of extension of the pulsar wind nebula scenario, several of the fundamental short comings of the toroidal field model of the Crab Nebula (Kennel & Coroniti 1984b) can be overcome as argued by Luo et al (2020).…”

Section: Magnetic Field Structurementioning

confidence: 99%

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Phenomenological modelling of the Crab Nebula's broad band energy spectrum and its apparent extension

Dirson¹,

Horns²

2022

Preprint

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Context. The Crab Nebula emits bright non-thermal radiation from radio to the most energetic photons. The underlying physical model of a relativistic wind from the pulsar terminating in a hydrodynamic standing shock remains unchanged since the early 1970s. In this model, an increase of the toroidal magnetic field downstream from the shock is expected. Aims. Using the recent measurements of the spatial extension and improved spectroscopy of the gamma-ray nebula, it has become for the first time feasible to determine in a robust way both the strength as well as the radial dependence of the magnetic field in the downstream flow. Methods. We introduce a detailed radiative model to calculate non-thermal synchrotron and inverse Compton as well as thermal dust emission self-consistently to compare quantitatively with observational data. Special care is given to the radial dependence of electron and seed field density.Results. The radiative model is used to estimate the parameters of electrons and dust in the nebula. A combined fit based upon a χ 2 minimisation reproduces successfully the complete data set used. For the best-fitting model, the energy density of the magnetic field dominates over the particle energy density up to a distance of ≈ 1.3 r s (r s : distance of the termination shock from the pulsar). The very high energy (VHE: E > 100 GeV) gamma-ray spectra set the strongest constraints on the radial dependence of the magnetic field: B(r) = (264 ± 9) µG(r/r s ) −0.51±0.03 . Conclusions. The reconstructed magnetic field and its radial dependence indicates a ratio of Poynting to kinetic energy flux σ ≈ 0.1 at the termination shock, ≈ 30 times larger than estimated up to now. Consequently, the confinement of the nebula would require additional mechanisms to slow down the flow through e.g. excitation of small-scale turbulence with possible dissipation of magnetic field.

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Section: Magnetic Field Structurementioning

confidence: 56%

Section: Magnetic Field Structurementioning

confidence: 99%

Phenomenological modelling of the Crab Nebula's broad band energy spectrum and its apparent extension

Dirson¹,

Horns²

2022

Preprint

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“…With the report of gamma-ray flares (100 MeV − 10 GeV) from the Crab nebula (Mayer et al 2013;Arakawa et al 2020), it is thought that the MeV radiation might be produced in a special region with special physical conditions (e.g. the particles are accelerated by the magnetic reconnection or a small-scale magnetic turbulence is present) which are different from the typical conditions expected in the Crab nebula (Cerutti et al 2012;Kelner et al 2013;Luo et al 2020). The radio to UV emission is the most complicated and its resulting broadband SEDs include synchrotron emission of the accumulated long-living leptons, thermal emission from the dust in the nebula, and optical line emission from the filaments (Meyer et al 2010).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Ultrahigh-energy Gamma-Ray Radiation from the Crab Pulsar Wind Nebula

Nie,

Liu,

Jiang

et al. 2022

Preprint

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It has been long debated whether the high-energy gamma-ray radiation from the Crab nebula stems from leptonic or hadronic processes. In this work, we investigate the multiband nonthermal radiation from the Crab pulsar wind nebula with the leptonic and leptonic−hadronic hybrid models, respectively. Then we use the Markov Chain Monte Carlo sampling technology and method of sampling trace to study the stability and reasonability of the model parameters according to the recently observed results and obtain the best-fitting values of parameters. Finally, we calculate different radiative components generated by the electrons and protons in the Crab nebula. The modeling results indicate that the pure leptonic origin model with the one-zone only can partly agree with some segments of the data from various experiments (including the PeV gamma-ray emission reported by the LHAASO and the other radiation ranging from the radio to very-high-energy gamma-ray wave band), and the contribution of hadronic interaction is hardly constrained. However, we find that the hadronic process may also contribute, especially in the energy range exceeding the PeV. In addition, it can be inferred that the higher energy signals from the Crab nebula could be observed in the future.

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“…It is the same for all synchrotron-emitting particles, from radio to X-rays. The length (2) is typically much larger than the inter-particle distance of radio emitting particles, n −1/3 ≈ 10 2 cm (Shklovsky 1970;Atoyan 1999;Luo et al 2020)…”

Section: Synchrotron Emissionmentioning

confidence: 99%

Radiation formation length in astrophysical high brightness sources

Lyutikov¹

2021

Preprint

Self Cite

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The radiation formation length for relativistic particles, l c ∼ γ 2 λ (γ is the Lorentz factor, λ is the emitted wavelength), is much lager than the inter-particle distances in many astrophysical applications. This leads to the importance of plasma effects even for the high energy emission. The consequences are nontrivial: (i) averaging of the phases of the emitting particles reduces the power (a.k.a., a circle current does not emit); (ii) density fluctuations may lead to the sporadic production of coherent emission; (iii) plasma effects during assembly of a photon may lead to the suppression of the emission (Razin-Tsytovich effect for the superluminal modes), or, in the opposite limit of subluminous normal modes, to the newly discussed synchrotron super-radiance. For synchrotron emission the radiation formation length is the same for all emitted waves, ∼ c/ω B (non-relativistic Larmor length); for curvature emission it is R/γ -macroscopically long in pulsar magnetospheres (e.g. kilometers for radio). The popular model of "coherent curvature emission by bunches", with kilometers-long radiation formation length, particles swinging-out in a rotating magnetosphere before they finish emitting a wave, extreme requirements on the momentum spreads, and demands on the electric energy needed to keep the electrostatically repulsing charges together, all make that model internally inconsistent. Long radiation formation lengths affect how emission from PIC simulations should be interpreted: phases of the emitted wave should be added over the radiation formation length, not just the powers from the instantaneous acceleration of each particle.

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Turbulent Model of Crab Nebula Radiation

Cited by 17 publications

References 93 publications

Phenomenological modelling of the Crab Nebula's broad band energy spectrum and its apparent extension

Phenomenological modelling of the Crab Nebula's broad band energy spectrum and its apparent extension

Ultrahigh-energy Gamma-Ray Radiation from the Crab Pulsar Wind Nebula

Radiation formation length in astrophysical high brightness sources

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