Delayed explosions of spinning white dwarfs in single degenerate models for type Ia supernovae

NOMOTO, K.; BENVENUTO, O. G.; PANEI, J. A.; KITAMURA, H.; HACHISU, I.

Roma

Congreso; The Fourteenth Marcel Grossmann Meeting; 2015

University of Rome ?La Sapienza?

We study the occurrence of delayed Type Ia supernovae in the single degenerate (SD) scenario. We assume that a massive carbon-oxygen (CO) white dwarf (WD) accretes matter coming from a companion star, making it to spin at the critical rate. We assume uniform rotation due to magnetic field coupling. The carbon ignition mass for non-rotating WDs is M^NR_ig≈1.38 M_sun; while for the case of uniformly rotating WDs it isfew percents larger (M^NR_ig≈1.43 M_sun). When accretion rate decreases, the WD begins to lose angular momentum, shrinks and spins up; however it does not overflow its critical rotation rate, avoiding mass shedding. Thus, angular momentum losses can lead the CO WD interior to compression and carbon ignition, which would induce a Type Ia supernova. The delay, largely due to angular momentum losses timescale, may be large enough to allow the companion star to evolve to a He WD, becoming undetectable at the moment of explosion. This scenario supports the occurrence of delayed SNe Ia if the final CO WD mass is 1.38 M_sun < M < 1.43 M_sun. We also find that if the delay is longer than ∼ 3 Gyr, the WD would become too cold to explode, rather undergo collapse.