Spatial Variations of the Synchrotron Spectrum Within Tycho's Supernova Remnant (3C 10): A Spectral Tomography Analysis of Radio Observations at 20 and 90 Centimeter Wavelengths
NAVAL ACADEMY ANNAPOLIS MD DEPT OF PHYSICS
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We present subarcminute-resolution approx. 10, high-dynamic range radio observations of Tychos supernova remnant 3C 10 at lambda 20 cm and lambda 90 cm with the Very Large Array VLA. The thermal-noise-limited 90 cm image has been compensated properly for the noncoplanar characteristics of the VLA and is the most sensitive low-frequency image of this source presently available. We use these images to search for spatial variations in the continuum radio spectral index within the remnant. Such spatial variations should be related to the electron acceleration processes associated with the evolution of the blast wave. We have also utilized, for the first time in an analysis of a supernova remnant, spectral tomography to search for localized regions within which the spectral index is different from the surroundings. We have identified 13 filaments, ranging in size from approx. 40 to approx. 260, embedded in a smoother, background component. The average spectral index of the filaments alpha -0.52 plusminus 0.02 is consistent with that of the background component alpha -0.500 plusminus 0.007. However, the filaments in the outer rim show a trend such that brighter filaments have a flatter spectral index. This trend may be due to either supernova remnant SNR blast wave-ambient medium interactions or internal inhomogeneities of the magnetic field within the remnant. These hypotheses could be tested by an image at comparable resolution and fidelity at a third frequency.