1998A&A...334.1060V

In the present paper we investigate the linear stage of instabilities which might take place at the shock front of young supernova remnants (hereafter SNR), deriving expressions for the characteristic wavelength and typical growth time scales. These theoretical predictions are compared with very high resolution observations of Tycho's SNR obtained with the Very Large Array at 1.4GHz. The images obtained with an angular resolution of the order of 1 arcsec and with very good sensitivity, clearly reveal the presence of corrugated (wavelike) structures with remarkable spatial regularity, visible mainly along the northeastern part of the SNR shell. We argue that the Rayleigh-Taylor instability (hereafter R-T) is responsible for the observed structures. Using physical parameters of Tycho's remnant and its environment derived from different X-ray observational studies, we computed the expected wavelength and growth rate for the most unstable R-T mode including viscosity and magnetic effects. The wavelength we derive is fully compatible with the one measured directly on the image (λ_obs∼0.9pc). The growth rate derived for this mode indicates that the R-T instability is still undergoing its linear stage.