On the Magnetic Fields and Particle Acceleration in Cassiopeia A
By J. Vink. 2002
327 citations recorded by the source corpus.
We investigate the nonthermal X-ray emission from Cas A, using BeppoSAX, Compton Gamma Ray Observatory OSSE, and Chandra data. For the hard X-ray continuum we test the model proposed by Laming, which invokes nonthermal bremsstrahlung from electrons accelerated by lower hybrid plasma waves. The justification for this model comes from our determination of a lower limit to the average magnetic field of B > 0.5 mG. For such high magnetic fields, the synchrotron losses are severe enough that most of the electron populations responsible for the radio emission have maximum electron energies well below the limit for which X-ray synchrotron emission is important. However, we do suggest that the rim surrounding Cas A, seen in Chandra continuum images, is X-ray synchrotron emission. The width of this rim of 1.″5-4'' can be used to infer the magnetic field near the shock front, for which we estimate B = 0.08-0.16 mG and electron energies of ~57-40 TeV. This magnetic field strength is lower than the average magnetic field but higher than what may be expected from shocked interstellar medium, suggesting either a high magnetic field in the wind of the progenitor or rapid postshock field amplification by nonlinear growth of plasma waves. Combining the two magnetic field measurements, we have constructed a simple two-zone model. Most of the radio emission comes from inside Cas A, where the magnetic field is strong. In contrast, the inverse Compton emission is dominated by emission from near the shock front. Only for our lower limit on the magnetic field strength near the shock front is it possible to explain the recent detection of TeV emission by the High Energy Gamma Ray Astronomy experiment with inverse Compton emission, for which, in addition, we have to assume a rather high far-infrared photon density that should be twice as high as our best estimate of ~70 cm-3. Pion decay is therefore likely to be the dominant emission from Cas A at TeV energies.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/e384f6e6a6e080b7c4dcce07b3f65bfbc736df8a
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Citations in the corpus
- FERMI-LAT DISCOVERY OF GeV GAMMA-RAY EMISSION FROM THE YOUNG SUPERNOVA REMNANT CASSIOPEIA A (2010, methodology): “Recent studies showed electron acceleration to multi-TeV energies is likely to take place also at the reverse shock in the supernova ejecta (Uchiyama & Aharonian 2008; Helder & Vink 2008).”
- Teraelectronvolt Astronomy (2010, result): “…magnetic fields can be estimated from the cooling length-scale of electrons produced at the shock front (see for example Berezhko, Ksenofontov & Völk 2003, Vink & Laming 2003), with results consistent with the predicted B2 ∝ nu3 dependence, where n is the ambient density and u the shock velocity.”
- Cosmic-ray energy spectrum and composition up to the ankle - the case for a second Galactic component (2016, background): “This is also supported by observations of thin X-ray filaments in supernova remnants which can be explained as due to rapid synchrotron losses of energetic electrons in the presence of strong magnetic fields (Vink & Laming 2003; Parizot et al. 2006).”
- Turbulent amplification of magnetic field and diffusive shock acceleration of cosmic rays (2004, background): “…(Longair 1994) in some parts of some young SNR. Recent analysis of the morphology of X-ray emission close to the outer shocks of SN1006 (Berezhko et al. 2003) and Cas A (Vink & Laming 2003) imply that strong magnetic fields are needed for rapid synchrotron loss by high-energy electrons.”
- TURBULENCE AND MAGNETIC FIELD AMPLIFICATION IN SUPERNOVA REMNANTS: INTERACTIONS BETWEEN A STRONG SHOCK WAVE AND MULTIPHASE INTERSTELLAR MEDIUM (2009, background): “The evidence for magnetic field amplification in SNR has been also obtained from the thickness of X-ray filaments that shows typicallyB ∼ 100 microGauss (Bamba et al. 2003, 2005a, 2005b; Vink & Laming 2003).”
- Nonlinear Diffusive Shock Acceleration with Magnetic Field Amplification (2006, background): “…et al. 2002), (2) broadband fits of synchrotron emission between radio and nonthermal X-rays (e.g., Berezhko et al. 2003; Völk et al. 2005; see also Cowsik & Sarkar 1980), and (3) sharp X-ray edges (e.g., Vink & Laming 2003; Bamba et al. 2003; Völk et al. 2005; Ellison&Cassam-Chenaı̈ 2005).”