New radio map of Cassiopeia A at 5 GHz

Bell, A. R.; Gull, S. F.; Kenderdine, S.

doi:10.1038/257463a0

Cited by 62 publications

(22 citation statements)

References 5 publications

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“…Bell et al 1975;Tuffs 1986;Braun 1987;Andersen et al 1991;Kassim et al 1995) and most probably also in the X-ray band (Allen et al 1997;Favata et al 1997). Since SNRs are widely suspected to be the main sources of the Galactic cosmic rays (CRs) up to energies of at least 10 15 eV, this youngest Galactic SNR offers an important possibility to test this CR origin hypothesis.…”

Section: Introductionmentioning

confidence: 99%

Gamma-ray emission from Cassiopeia A produced by accelerated cosmic rays

Berezhko¹,

Pühlhofer²,

Völk³

2003

A&A

119

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Abstract. The nonlinear kinetic model of cosmic ray (CR) acceleration in supernova remnants (SNRs) is used to describe the relevant properties of Cassiopeia A (Cas A). In order to reproduce the SNR's observed size, expansion rate and thermal X-ray emission we employ a piecewise homogeneous model for the progenitor's circumstellar medium developed by Borkowski et al. (1996). It consists of a tenuous inner wind bubble, a dense shell of swept-up red supergiant wind material, and a subsequent red supergiant wind region. A quite large SNR interior magnetic field B d ≈ 1 mG is required to give a good fit for the radio and X-ray synchrotron emission. The steep radio spectrum is consistent with efficient proton acceleration which produces a significant shock modification and leads to a steep electron spectrum at energies e < 1 GeV. The calculated integral γ-ray flux from Cas A, F γ ∝ −1 γ , is dominated by π 0 -decay γ-rays due to relativistic protons. It extends up to roughly 30 TeV if CR diffusion is as strong as the Bohm limit. At TeV energies it satisfactorily agrees with the value 5.8 × 10 −13 cm −2 s −1 detected by the HEGRA collaboration.

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Section: Introductionmentioning

confidence: 99%

Gamma-ray emission from Cassiopeia A produced by accelerated cosmic rays

Berezhko¹,

Pühlhofer²,

Völk³

2003

A&A

119

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“…Cassiopeia A (Cas A), with right ascension (RA) and declination (DEC) (23.385 h , 58.800 • ), is a prominent shell type supernova remnant and a bright source of synchrotron radiation observed at radio frequencies, see Bell et al (1975); Tuffs et al (1986), and in the X-ray band, see Allen et al (1997), Favata et al (1997). The remnant results from the youngest known Galactic supernova, whose explosion took place around 1680.…”

Section: Introductionmentioning

confidence: 99%

Observation of VHE γ-rays from Cassiopeia A with the MAGIC telescope

Albert

Aliu²,

Anderhub

et al. 2007

A&A

102

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Aims. We searched for very high energy (VHE) γ-ray emission from the supernova remnant Cassiopeia A Methods. The shell-type supernova remnant Cassiopeia A was observed with the 17 m MAGIC telescope between July 2006 and January 2007 for a total time of 47 h. Results. The source was detected above an energy of 250 GeV with a significance of 5.2σ and a photon flux above 1 TeV of (7.3 ± 0.7 stat ± 2.2 sys ) × 10 −13 cm −2 s −1 . The photon spectrum is compatible with a power law dN/dE ∝ E −Γ with a photon index Γ = 2.3 ± 0.2 stat ± 0.2 sys . The source is point-like within the angular resolution of the telescope.

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“…The many detailed observations that have been made of Cas A, the youngest galactic SNR, allow several tests of the theoretical model. The chaotic, cellular structure of its radio shell (Bell, Gull & Kenderdine, 1975), with its turbulent internal velocity field (Bell, 1977), as well as the strong anticorrelation between the polarized and unpolarized emission (Dickel and Greisen, 1979) do argue strongly in favour of small-scale turbulence as the origin of the radiating electrons and magnetic field. Independent observational evidence for the turbulent enhancement of the magnetic field has also been presented (Cowsik and Sarkar 1980).…”

Section: The Supernova Remnant Cassiopeia-amentioning

confidence: 99%