Supernovae (SNe) are massive destruction of stars. Because of their large distances it is difficult to know the kind of the star that had exploded. One of the ways to investigate this issue is to study the interaction of the SN with the ambient medium. This medium, also called circumstellar medium (CSM), is shaped by the pre-explosion mass loss history of the progenitor star. Therefore, depending on different kind of stars the CSM would be different. When a SN interact with this CSM strong shocks are formed. These shocks radiate part of their energy in radio and the flux of this emission depends on the nature of the CSM. As the real density structures of the SN ejecta and CSM are quite complicated the best way to study the non-linear nature of the interaction in detail is through numerical simulations.
According to our previous proposal, we have performed the interaction of the SN ejecta with the CSM using the Flash code, which is a hydrodynamical code, beyond 20 years since the explosion has occurred. From this simulation we have confirmed that in order to explain the late time radio and X-ray downturn for SN 1993J we are required a rapid decrease in the density of the CSM beyond a certain radius. This result has enabled us to extract useful information about the evolution of the binary progenitor of SN 1993J. We did a similar study with SN 2011dh, which is a type IIb SN like SN 1993J, and found from radio and X-ray study that the evolution is so far consistent with a shock interacting a wind medium. In this case, till now, there is not any indication of a rapid drop in CSM density. According to the observational evidence SNe 1993J and 2011dh originate from similar kind of progenitors (yellow supergiant). Therefore, one may expect almost similar kind of evolution of progenitors before explosion. In this respect our study provides important clue about the mass loss mechanisms of yellow supergiants before explosion. We are currently writing these results in a manuscript for publication. Our manuscript is expected to be submitted for publication in an international Journal at the end of July or first week of August. For this project we are almost done with the hydro-simulations. We may require to run another 2/3 simulations in July.
There is another project which we will start now. In the new project we will do the same SN-CSM interaction, using FLASH, but for SNe which are few hundred years old. For old SNe (SNRs) the radio emitting shocks are often very well resolved. Therefore, by studying SNRs one may get important clues about the progenitors of SNe. However, these are large scale simulations, where micro physics plays a dominant role in shock dynamics. Therefore the computing cost increases. The access of the powerful computing infrastructure is therefore essential to study these complex systems.