Inverse Compton emission from a cosmic-ray precursor in RX J1713.7−3946

Ohira, Yutaka; Yamazaki, Ryo

doi:10.1016/j.jheap.2017.03.001

Cited by 23 publications

(19 citation statements)

References 41 publications

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“…However, for strong shocks of SNRs, the spectral index is close to 2, leading to a strong rigidity dependence of the escape rate of CRs from the Galaxy, which thus gives large anisotropies of the arrival directions of high energy CRs, in conflict with observations (Hillas 2005;Ahlers & Mertsch 2017). Multi-wavelength observations also do not support a single power-law particle distribution in SNRs (Helder et al 2012;Zeng et al 2017;Ohira & Yamazaki 2017).…”

mentioning

confidence: 83%

Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants

Zhang

Liu

Yuan

2017

ApJL

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Recent precise measurements of cosmic ray (CR) spectra show that the energy distribution of protons is softer than those of heavier nuclei, and there are spectral hardenings for all nuclear compositions above ∼200 GV. Models proposed for these anomalies generally assume steady-state solutions of the particle acceleration process. We show that, if the diffusion coefficient has a weak dependence on the particle rigidity near shock fronts of supernova remnants (SNRs), time-dependent solutions of the linear diffusive shock acceleration at two stages of SNR evolution can naturally account for these anomalies. The high-energy component of CRs is dominated by acceleration in the free expansion and adiabatic phases with enriched heavy elements and a high shock speed. The low energy component may be attributed to acceleration by slow shocks propagating in dense molecular clouds with low metallicity in the radiative phase. Instead of a single power-law distribution, the spectra of time-dependent solutions soften gradually with the increase of energy, which may be responsible for the "knee" of CRs.

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mentioning

confidence: 83%

Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants

Zhang

Liu

Yuan

2017

ApJL

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“…In the Sedov phase of SNRs, shock speed decreases, and so does the E age max . In combination with an efficient injection, the time-integrated electron distribution may also be described by a broken power-law function (Ohira & Yamazaki 2017).…”

Section: Modelingmentioning

confidence: 99%

Electron Acceleration in Middle-age Shell-type γ-Ray Supernova Remnants

Zhang

Liu²

2019

ApJ

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Over the past decade, γ-ray observations of supernova remnants (SNRs) and accurate cosmic-ray (CR) spectral measurements have significantly advanced our understanding of particle acceleration in SNRs. In combination with multiwavelength observations of a large sample of SNRs, it has been proposed that the highest energy particles are mostly accelerated in young remnants, and the maximum energy that middle-age and old SNRs can accelerate particles to decreases rapidly with the decrease in shock speed. If SNRs dominate the CR flux observed at Earth, a large number of particles need to be accelerated in old SNRs for the soft CR spectrum even though they cannot produce very high-energy CRs. With radio, X-ray, and γ-ray observations of seven middle-age shell-type SNRs, we derive the distribution of high-energy electrons trapped in these remnants via a simple one-zone leptonic emission model and find that their spectral evolution is consistent with such a scenario. In particular, we find that particle acceleration by shocks in middle-age SNRs with an age of t can be described by a unified model with the maximum energy decreasing as t −3.1 and the number of GeV electrons increasing as t 2.5 in the absence of escape from SNRs.

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“…For middle-aged SNRs, the emitting electron spectrum is usually given by a broken power law function with a high-energy cut-off. 38,39 We followed this description and found that when the radio and X-ray data in the tail region are well reproduced with the synchrotron radiation of electrons, the gamma-ray spectrum cannot be explained solely by electrons of the same population, and the GeV data disfavor a magnetic field much weaker than B = 6 mG. As shown in Figure 4, the GeV-TeV gamma-ray emission may or may not be reproduced by the inverse Compton (IC) radiation of electrons, depending on the assumed magnetic field. However, the spectrum beyond 30 TeV cannot be interpreted by the IC radiation, because the Klein-Nishina effect suppresses the cross-section of IC scattering at high energies and softens the spectrum (Figure S3).…”

Section: Report Llmentioning

confidence: 99%

Revealing a peculiar supernova remnant G106.3+2.7 as a petaelectronvolt proton accelerator with X-ray observations

Liu

Niu

et al. 2021

The Innovation

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Revealing a peculiar supernova remnant G106.3+2.7 as a petaelectronvolt proton accelerator with X-ray observations. The Innovation 2(2), 100118.Supernova remnants (SNRs) have long been considered as one of the most promising sources of Galactic cosmic rays. In the SNR paradigm, petaelectronvolt (PeV) proton acceleration may only be feasible at the early evolution stage, lasting a few hundred years, when the SNR shock speed is high. While evidence supporting the acceleration of PeV protons in young SNRs has yet to be discovered, X-ray synchrotron emission is an important indicator of fast shock. Here, we report the first discovery of X-ray synchrotron emission from the possibly middle-aged SNR G106.3+2.7, implying that this SNR is still an energetic particle accelerator despite its age. This discovery, along with the ambient environmental information, multiwavelength observation, and theoretical arguments, supports SNR G106.3+2.7 as a likely powerful proton PeV accelerator.

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Inverse Compton emission from a cosmic-ray precursor in RX J1713.7−3946

Cited by 23 publications

References 41 publications

Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants

Anomalous Distributions of Primary Cosmic Rays as Evidence for Time-dependent Particle Acceleration in Supernova Remnants

Electron Acceleration in Middle-age Shell-type γ-Ray Supernova Remnants

Revealing a peculiar supernova remnant G106.3+2.7 as a petaelectronvolt proton accelerator with X-ray observations

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