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We present archival radio observations of SN1996cr from ATCA and MOST, andmodel its radio lightcurves using X-ray constrained hydrodynamical simulationsof the interaction between the SN ejecta and the CSM. The early radio data showsigns of free-free absorption (FFA), which decreases gradually and is minimalabove 1.4 GHz after day ~3000. FFA optical depth constraints provide estimatesof the CSM free electron density, which allows insight into the ionisation ofSN1996cr's CSM and offers a test on the density distribution adopted by thehydrodynamical simulation. The intrinsic spectral index of the radiation showsevidence for spectral flattening, which is characterised by alpha = 0.852 +/-0.002 at day 3000 and a decay rate of d_alpha = -0.014 +/- 0.001 yr^-1. Thesimilarity in the spectral flattening of SN1987A, SN1993J, and SN1996crsuggests this may be a relatively common feature of SNe/CSM shocks. We adoptthis spectral index variation to model the synchrotron radio emission of theshock, and consider several scalings that relate the parameters of thehydrodynamical simulation to the magnetic field and electron distribution. Thesimulated light curves match the large-scale features of the observed lightcurves, but fail to match certain tightly constraining sections. This suggeststhat simple energy density scalings may not be able to account for thecomplexities of the true physical processes at work, or alternatively, that theparameters of the simulation require modification in order to accuratelyrepresent SN1996cr's CSM.

Performing a stellar autopsy using the radio-bright remnant of SN 1996cr