Rotating Type Ia SN Progenitors: Explosion and Light Curves

Abstract

Based on the rigidly rotating progenitor models found to be able to grow up to the canonical Chandrasekhar mass limit and beyond, and undergo a thermonuclear explosion, we compute the explosions, detailed nucleosynthesis, and corresponding light curves by means of a one-dimensional hydrodynamic code. Our results show that the inclusion of rotation in the evolution of the progenitors determines, in a natural way, a variation in the explosive physical conditions, mainly different explosive ignition densities (2:08 ; 10 9 to 3:34 ; 10 9 g cm À3 ), total masses (1.39-1.48 M ), and binding energies (À5:3 ; 10 50 to À6:6 ; 10 50 ergs). Such a spread is related to the rotational velocity at the explosive carbon ignition stage and to the efficiency of angular momentum loss during the last part of the progenitor evolution. We explore the final outcome in the framework of the delayed detonation explosion models by fixing the value of the transition density and by considering two different braking efficiencies. Within the explored parameter space, the bolometric light curves at maximum show differences of $0.1 mag due to the different amount of 56 Ni synthesized during the explosion. Although rigid rotation cannot be considered responsible for the diversities in the observational properties of SNe Ia, it could explain the dispersion in the magnitude at maximum of standardized events. We also find that those models with high ignition densities produce a central remnant in which most of the neutron-rich species synthesized during the explosion are trapped.

TYPE Ia SUPERNOVAE: CAN CORIOLIS FORCE BREAK THE SYMMETRY OF THE GRAVITATIONAL CONFINED DETONATION EXPLOSION MECHANISM?

“…On another note, moderate spinning WDs could be no so rare because: 1) exploding WDs rotating with Ω ≤ 1 s −1 are expected for compact systems with total masses close to the canonical Chandrasekhar-mass limit. The physical structure of these WD would be similar to that of their non-rotating counterparts (Piersanti et al 2003;Domínguez et al 2006), and 2) as commented in the introduction the central deflagration of a fast spinning WD leaves a large amount of unburnt matter, which is incompatible with observations (Pfannes et al 2010a).…”

“…This is actually a wrong hypothesis because the same accretion process which builds up the mass of the WD also transfers angular momentum from the disc to the compact object. As a result the WD could be spinning at angular velocities as high as Ω ≃ 2−3 s −1 at the moment of the ignition (Piersanti et al 2003;Yoon & Langer 2005;Domínguez et al 2006). The reduction in the effective gravity caused by the centrifugal force changes the structure of the progenitor prior the explosion.…”

The Evolution of Compact Binary Star Systems

“…On the other hand, usually, as an event beneath the “standard candle”, an explosion of a non-rotating WD with the Chandrasekhar mass (≃ 1.38 M ⊙ ) is considered. Rotation of progenitors may increase the critical mass and make SNe Ia less reliable for cosmological use [154, 155]. …”

Supernova 2014J at M82 – II. Direct analysis of a middle-class Type Ia supernova

“…Thus, SN 2014J could have been ignited at a central density smaller than that for SN 2011fe, due to a higher accretion rate or, in case of rotation, to a shorter time-scale for the angular momentum losses (Piersanti et al 2003;Domínguez et al 2006). If this was the case, the light curve tail of SN 2011fe would be dimmer than that of SN 2014J, as it seems to be in B band and less markedly in V , although late observations in the optical of SN 2014J have not yet been published.…”