Reacceleration of electrons in supernova remnants

Pohl, M.; Wilhelm, A.; Telezhinsky, I.

doi:10.1051/0004-6361/201425027

Cited by 30 publications

(30 citation statements)

References 47 publications

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“…6 shows a comparison between F (x) and Fσ( √ 2x)/ √ 2 (where the √ 2 factors come from the fact that, in the completely random case, the effective MF strength would be equal to √ 2σ). The present analysis is in a sense similar to that in Pohl et al (2015); the main differences are that that paper assumes a 1-D Gaussian distribution for the MF values and an approximation of F (x), while here we use a 2-D one, which we think is more correct, and the exact F (x) function: the interesting fact is that our approach luckily allows an exact solution.…”

Section: Mono-energetic Electron Distributionmentioning

confidence: 99%

Radio polarization maps of shell-type supernova remnants – I. Effects of a random magnetic field component and thin-shell models

Bandiera¹,

Petruk²

2016

Mon. Not. R. Astron. Soc.

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The maps of intensity and polarization of the radio synchrotron emission from shelltype supernova remnants (SNRs) contain a considerable amount of information, although of not easy interpretation. With the aim of deriving constraints on the 3-D spatial distribution of the emissivity, as well as on the structure of both ordered and random magnetic fields (MFs), we present here a scheme to model maps of the emission and polarization in SNRs.We first generalize the classical treatment of the synchrotron emission to the case in which the MF is composed by an ordered MF plus an isotropic random component, with arbitrary relative strengths. In the case of a power-law particle energy distribution, we derive analytic formulae that formally resemble those for the classical case. We also treat the case of a shock compression of a fully random upstream field and we predict that the polarization fraction in this case should be higher than typically measured in SNRs. We implement the above treatment into a code, which simulates the observed polarized emission of an emitting shell, taking into account also the effect of the internal Faraday rotation.Finally, we show simulated maps for different orientations with respect to the observer, levels of the turbulent MF component, Faraday rotation levels, distributions of the emissivity (either barrel-shaped or limited to polar caps), and geometries for the ordered MF component (either tangential to the shell, or radial). Their analysis allows us to outline properties useful for the interpretation of radio intensity and polarization maps.

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Section: Mono-energetic Electron Distributionmentioning

confidence: 99%

Radio polarization maps of shell-type supernova remnants – I. Effects of a random magnetic field component and thin-shell models

Bandiera¹,

Petruk²

2016

Mon. Not. R. Astron. Soc.

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“…(4)) using the above parameters (Telezhinsky et al 2012a). We then calculate emission spectra and intensity maps at two epochs, at 1600 and at 1610 yr, including pion-decay (Huang et al 2007), inverse Compton (IC) and synchrotron emission in turbulent magnetic field (Pohl et al 2015). The dense gas shell radially extends from 8.75 pc to 9.05 pc from the SNR center, and so the shock does not interact with the dense material, but CRs in the shock precursor can efficiently reach the dense gas.…”

Section: Detailed Modelingmentioning

confidence: 99%

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Federici¹,

Pohl

Telezhinsky

et al. 2015

A&A

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Context. RX J1713.7-3946 is the brightest shell-type supernova remnant (SNR) of the TeV γ-ray sky. Earlier Fermi-LAT results on low energy γ-ray emission suggested that, despite large uncertainties in the background determination, the spectrum is inconsistent with a hadronic origin. Aims. We update the GeV-band spectra using improved estimates for the diffuse Galactic γ-ray emission and more than double the volume of data. We further investigate the viability of hadronic emission models for RX J1713.7-3946. Methods. We produced a high-resolution map of the diffuse Galactic γ-ray background corrected for the HI self-absorption and used it in the analysis of more than five years worth of Fermi-LAT data. We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic rays in SNR. We then determined spectra of hadronic γ-ray emission from RX J1713.7-3946, separately for the SNR interior and the cosmic-ray precursor region of the forward shock, and computed flux variations that would allow us to test the model with observations. Results. We find that RX J1713.7-3946 is now detected by Fermi-LAT with very high statistical significance, and the source morphology is best described by that seen in the TeV band. The measured spectrum of RX J1713.7-3946 is hard with index γ = 1.53 ± 0.07, and the integral flux above 500 MeV is F = (5.5 ± 1.1) × 10 −9 photons cm −2 s −1 . We demonstrate that scenarios based on hadronic emission from the cosmic-ray precursor region are acceptable for RX J1713.7-3946, and we predict a secular flux increase at a few hundred GeV at the level of around 15% over ten years, which may be detectable with the upcoming Cherenkov Telescope Array (CTA) observatory.

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“…However, it can be reproduced if we account for other possible processes which might operate in the SNR, e.g. stochastic re-acceleretation of particles at the turbulence in the immediate downstream region of the shock (Pohl et al, 2015). It should also be noted that the reported value of the detected radio flux can be misleading as the remnant is located in a very crowded region with a very complicated background.…”

Section: Discussionmentioning

confidence: 94%

Magnetic field damping in the Vela Jr. SNR

Sushch¹,

Brose²,

Pohl³

2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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Vela Jr. (RX J0852.0−4622) is one of just a few known supernova remnants (SNRs) with the resolved shell across the whole electromagnetic spectrum from radio to very-high-energy (>100 GeV; VHE) gamma-rays. Its proximity and large size allow for detailed spatially resolved observations of the source making Vela Jr. one of the primary sources used for the study of particle acceleration and emission mechanisms in SNRs. High-resolution X-ray observations reveal steepening of the spectrum towards the interior of the remnant. In this study we aim for the self-consistent radiation model of Vela Jr. which at the same time would explain the broadband emission from the source and its spatially-dependent features. We solve the full particle transport equation combined with the high-resolution 1D hydrodynamic simulations (using Pluto code) and subsequently calculate the radiation from the remnant. We show that accounting for the damping of strong magnetic turbulence downstream of the forward shock might explain the observed radial dependence of the X-ray spectrum.

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Reacceleration of electrons in supernova remnants

Cited by 30 publications

References 47 publications

Radio polarization maps of shell-type supernova remnants – I. Effects of a random magnetic field component and thin-shell models

Radio polarization maps of shell-type supernova remnants – I. Effects of a random magnetic field component and thin-shell models

Analysis of GeV-bandγ-ray emission from supernova remnant RX J1713.7-3946

Magnetic field damping in the Vela Jr. SNR

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