Temporal Evolution of Nonthermal Spectra from Supernova Remnants

Sturner, Steven J.; Skibo, J. G.; Dermer, C. D.; Mattox, J. R.

doi:10.1086/304894

Cited by 131 publications

(252 citation statements)

References 34 publications

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“…A simple model of the evolution of SNRs is explained by three phases; the free expansion phase in which the shock velocity is constant, the Sedov-Taylor phase in which the shock expands adiabatically, and the radiative phase in which the energy is lost by radiation (e.g., Sturner et al 1997;Yamazaki et al 2006). The shock velocity V s for each phase is written by function of the age of SNRs t as follows: is an expansion energy in unit of 10 51 erg, and n 0 is an uniform ambient density in unit of cm −3 .…”

Section: Appendix B Evolution Of Snrmentioning

confidence: 99%

THE JET AND ARC MOLECULAR CLOUDS TOWARD WESTERLUND 2, RCW 49, AND HESS J1023–575;¹²CO AND¹³CO (J= 2-1 andJ= 1-0) OBSERVATIONS WITH NANTEN2 AND MOPRA TELESCOPE

Furukawa

Ohama

Fukuda

et al. 2014

ApJ

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We have made new CO observations of two molecular clouds, which we call "jet" and "arc" clouds, toward the stellar cluster Westerlund 2 and the TeV γ -ray source HESS J1023−575. The jet cloud shows a linear structure from the position of Westerlund 2 on the east. In addition, we have found a new counter jet cloud on the west. The arc cloud shows a crescent shape in the west of HESS J1023−575. A sign of star formation is found at the edge of the jet cloud and gives a constraint on the age of the jet cloud to be ∼Myr. An analysis with the multi CO transitions gives temperature as high as 20 K in a few places of the jet cloud, suggesting that some additional heating may be operating locally. The new TeV γ -ray images by H.E.S.S. correspond to the jet and arc clouds spatially better than the giant molecular clouds associated with Westerlund 2. We suggest that the jet and arc clouds are not physically linked with Westerlund 2 but are located at a greater distance around 7.5 kpc. A microquasar with long-term activity may be able to offer a possible engine to form the jet and arc clouds and to produce the TeV γ -rays, although none of the known microquasars have a Myr age or steady TeV γ -rays. Alternatively, an anisotropic supernova explosion which occurred ∼Myr ago may be able to form the jet and arc clouds, whereas the TeV γ -ray emission requires a microquasar formed after the explosion.

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Section: Appendix B Evolution Of Snrmentioning

confidence: 99%

THE JET AND ARC MOLECULAR CLOUDS TOWARD WESTERLUND 2, RCW 49, AND HESS J1023–575;¹²CO AND¹³CO (J= 2-1 andJ= 1-0) OBSERVATIONS WITH NANTEN2 AND MOPRA TELESCOPE

Furukawa

Ohama

Fukuda

et al. 2014

ApJ

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“…The normalization is determined from the total kinetic energy of particles above 1 GeV, W 4 . The emission spectra from such energetic particle distributions can be readily obtained with the relevant emission mechanisms for a uniform emission region with a constant magnetic field (Sturner et al 1997;Kelner et al 2006). This simple emission model neither considers the electron energy losses, which will affect the energy content of energetic electrons, nor addresses the detailed process of particle acceleration, which may be constrained, however, by studying the characteristics of the model parameters (Fan et al 2010).…”

Section: The Mcmc Modeling Of the Emission Spectrummentioning

confidence: 99%

FermiLarge Area Telescope observations of the supernova remnant HESS J1731-347

Yang

Zhang

Yuan

et al. 2014

A&A

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Context. HESS J1731-347 has been identified as one of the few TeV-bright shell-type supernova remnants (SNRs). These remnants are dominated by nonthermal emission, and the nature of TeV emission has been continuously debated for nearly a decade. Aims. We carry out the detailed modeling of the radio to γ-ray spectrum of HESS J1731-347 to constrain the magnetic field and energetic particles sources, which we compare with those of the other TeV-bright shell-type SNRs explored before. Methods. Four years of data from Fermi Large Area Telescope (LAT) observations for regions around this remnant are analyzed, leading to no detection correlated with the source discovered in the TeV band. The Markov chain Monte Carlo method is used to constrain parameters of one-zone models for the overall emission spectrum. Results. Based on the 99.9% upper limits of fluxes in the GeV range, one-zone hadronic models with an energetic proton spectral slope greater than 1.8 can be ruled out, which favors a leptonic origin for the γ-ray emission, making this remnant a sibling of the brightest TeV SNR RX J1713.7-3946, the Vela Junior SNR RX J0852.0-4622, and RCW 86. The best-fit leptonic model has an electron spectral slope of 1.8 and a magnetic field of ∼30 μG, which is at least a factor of 2 higher than those of RX J1713.7-3946 and RX J0852.0-4622, posing a challenge to the distance estimate and/or the energy equipartition between energetic electrons and the magnetic field of this source. A measurement of the shock speed will address this challenge and has implications on the magnetic field evolution and electron acceleration driven by shocks of SNRs.

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“…The latter case would assume strong turbulence and little radio polarization (Stroman & Pohl 2009). Here we chose ξ = π/4 and applied the standard formula for synchrotron emission as for instance used by Sturner et al (1997). The IC emission was calculated using the full Klein-Nishina cross section (Blumenthal & Gould 1970) for relativistic electrons following Sturner et al (1997).…”

Section: Nonthermal Emissionmentioning

confidence: 99%

“…Here we chose ξ = π/4 and applied the standard formula for synchrotron emission as for instance used by Sturner et al (1997). The IC emission was calculated using the full Klein-Nishina cross section (Blumenthal & Gould 1970) for relativistic electrons following Sturner et al (1997). As the target photon field for the IC scattering we considered the microwave background only.…”

Section: Nonthermal Emissionmentioning

confidence: 99%

Acceleration of cosmic rays by young core-collapse supernova remnants

Telezhinsky

Dwarkadas

Pohl

2013

A&A

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Context. Supernova remnants (SNRs) are thought to be the primary candidates for the sources of Galactic cosmic rays. According to the diffusive shock acceleration theory, SNR shocks produce a power-law spectrum with an index of s = 2, perhaps nonlinearly modified to harder spectra at high energy. Observations of SNRs often indicate particle spectra that are softer than that and show features not expected from classical theory. Known drawbacks of the standard approach are the assumption that SNRs evolve in a uniform environment, and that the reverse shock does not accelerate particles. Relaxing these assumptions increases the complexity of the problem, because one needs reliable hydrodynamical data for the plasma flow as well as good estimates for the magnetic field (MF) at the reverse shock. Aims. We show that these two factors are especially important when modeling young core-collapse SNRs that evolve in a complicated circumstellar medium shaped by the winds of progenitor stars. Methods. We used high-resolution numerical simulations for the hydrodynamical evolution of the SNR. Instead of parametrizations of the MF profiles inside the SNR, we followed the advection of the frozen-in MF inside the SNR, and thus obtained the B-field value at all locations, in particular at the reverse shock. To model cosmic-ray acceleration we solved the cosmic-ray transport equation in test-particle approximation. Results. We find that the complex plasma-flow profiles of core-collapse SNRs significantly modify the particle spectra. Additionally, the reverse shock strongly affects the emission spectra and the surface brightness.

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Temporal Evolution of Nonthermal Spectra from Supernova Remnants

Cited by 131 publications

References 34 publications

THE JET AND ARC MOLECULAR CLOUDS TOWARD WESTERLUND 2, RCW 49, AND HESS J1023–575;¹²CO AND¹³CO (J= 2-1 andJ= 1-0) OBSERVATIONS WITH NANTEN2 AND MOPRA TELESCOPE

THE JET AND ARC MOLECULAR CLOUDS TOWARD WESTERLUND 2, RCW 49, AND HESS J1023–575;¹²CO AND¹³CO (J= 2-1 andJ= 1-0) OBSERVATIONS WITH NANTEN2 AND MOPRA TELESCOPE

FermiLarge Area Telescope observations of the supernova remnant HESS J1731-347

Acceleration of cosmic rays by young core-collapse supernova remnants

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Temporal Evolution of Nonthermal Spectra from Supernova Remnants

Cited by 131 publications

References 34 publications

THE JET AND ARC MOLECULAR CLOUDS TOWARD WESTERLUND 2, RCW 49, AND HESS J1023–575;12CO AND13CO (J= 2-1 andJ= 1-0) OBSERVATIONS WITH NANTEN2 AND MOPRA TELESCOPE

THE JET AND ARC MOLECULAR CLOUDS TOWARD WESTERLUND 2, RCW 49, AND HESS J1023–575;12CO AND13CO (J= 2-1 andJ= 1-0) OBSERVATIONS WITH NANTEN2 AND MOPRA TELESCOPE

FermiLarge Area Telescope observations of the supernova remnant HESS J1731-347

Acceleration of cosmic rays by young core-collapse supernova remnants

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Product

Resources

About

THE JET AND ARC MOLECULAR CLOUDS TOWARD WESTERLUND 2, RCW 49, AND HESS J1023–575;¹²CO AND¹³CO (J= 2-1 andJ= 1-0) OBSERVATIONS WITH NANTEN2 AND MOPRA TELESCOPE

THE JET AND ARC MOLECULAR CLOUDS TOWARD WESTERLUND 2, RCW 49, AND HESS J1023–575;¹²CO AND¹³CO (J= 2-1 andJ= 1-0) OBSERVATIONS WITH NANTEN2 AND MOPRA TELESCOPE