Type Ia supernovae within dense carbon-oxygen rich envelopes: a model for 'Super-Chandrasekhar' explosions? (MNRAS paper)
The most luminous thermonuclear supernovae (SNe) still constitute puzzles. Reconciling their intense luminosities with the standard theoretical interpretation for Type Ia SNe, according to which the light output is predominantly attributable to the decay of radioactive elements, would require very high nickel masses, implying ejecta masses beyond the Chandrasekhar mass - hence their other name, “Super-Chandrasekhar” explosions.
We have investigated one potential scenario for explaining such objects, namely invoking interaction between ejecta and circumstellar material (CSM). In particular, we studied the consequences of fairly normal SNe Ia exploding within compact and dense carbon-oxygen-rich CSM envelopes. Performing sophisticated radiation hydrodynamical simulations with the code STELLA, we demonstrated that a number of characteristic features of Super-Chandrasekhar objects can be reproduced by ejecta-CSM interaction. In particular, the ejecta kinematics seem to be compatible with observations and we find a good match in the overall shape of the computed optical light curve and SN 2009dc (a prototypical Super-Chandrasekhar SNe Ia). Nevertheless, achieving a significant optical luminosity boost is challenging in our calculations. The entire study is summarized in our paper which has just been accepted for publication in MNRAS.