Evolution of Rotating Accreting White Dwarfs and the Diversity of Type Ia Supernovae

Type Ia supernovae (SNe Ia) have relatively uniform light curves and spectralevolution, which make SNe Ia useful standard candles to determine cosmologicalparameters. However, the peak brightness is not completely uniform, and theorigin of the diversity has not been clear. We examine whether the rotation ofprogenitor white dwarfs (WDs) can be the important source of the diversity ofthe brightness of SNe Ia. We calculate the structure of rotating WDs with anaxisymmetric hydrostatic code. The diversity of the mass induced by therotation is ~0.08 Msun and is not enough to explain the diversity ofluminosity. However, we found the following relation between the initial massof the WDs and their final state; i.e., a WD of smaller initial mass willrotate more rapidly before the supernova explosion than that of larger initialmass. This result might explain the dependence of SNe Ia on their hostgalaxies.Comment: 7 pages, 6 figure