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Low Frequency Insights into Supernova Remnants

Published online by Cambridge University Press:  26 May 2016

K.K. Dyer ,
S.P. Reynolds ,
K.J. Borkowski ,
N.E. Kassim  and
C.K. Lacey
K.K. Dyer
Affiliation:
North Carolina State University, Physics Department Box 8202, Raleigh NC 27695
S.P. Reynolds
Affiliation:
North Carolina State University, Physics Department Box 8202, Raleigh NC 27695
K.J. Borkowski
Affiliation:
North Carolina State University, Physics Department Box 8202, Raleigh NC 27695
N.E. Kassim
Affiliation:
Naval Research Lab, Remote Sensing Division, Code 7213 Washington DC 20375-5351
C.K. Lacey
Affiliation:
Naval Research Lab, Remote Sensing Division, Code 7213 Washington DC 20375-5351

Abstract

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Low frequency observations at 330 and 74 MHz can provide new insights into supernova remnants (SNR). We can test theoretical predictions for spectral index variations. Nonlinear models of shock acceleration predict that the spectra from young SNR should be slightly concave rather than power laws — flattening toward higher energies. However, few SNR are bright and compact enough to be studied at millimeter wavelengths, restricting studies to the small range from 6 to 20 cm (a factor of 1.7 in electron energies). Observations at 330 MHz increase the electron energy baseline to a factor of 4, while providing sensitivity to larger spatial scales that are resolved out by centimeter-wavelength interferometers. Such observations can also separate thermal from nonthermal emission and detect excess free-free absorption associated with cool gas in remnants. Wide field images also provide an efficient census of both thermal and nonthermal sources over a large region.

Type
Part 5: Galactic Surveys and Extended Emission
Information
Symposium - International Astronomical Union , Volume 199: The Universe at Low Radio Frequencies , 2002 , pp. 291 - 294
Copyright
Copyright © Astronomical Society of the Pacific 2002 

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