Fission cycling in supernova nucleosynthesis: Active-sterile neutrino oscillations

Abstract

We investigate nucleosynthesis in the supernovae post-core bounce neutrino-driven wind environment in the presence of active-sterile neutrino transformation. We consider active-sterile neutrino oscillations for a range of mixing parameters: vacuum mass-squared differences of 0.1 eV 2 ≤ δm 2 ≤ 100 eV 2 , and vacuum mixing angles of sin 2 2θv ≥ 10 −4 . We find a consistent r-process pattern for a large range of mixing parameters that is in rough agreement with the halo star CS 22892-052 abundances and the pattern shape is determined by fission cycling. We find that the allowed region for the formation of the r-process peaks overlaps the LSND and NSBL (3+1) allowed region.

Neutrino-driven wind simulations and nucleosynthesis of heavy elements

“…Similar discussions with sterile neutrinos can be found in Refs. [60,61,62]. Recently, a systematic study has been performed [63] based on a low mass supernova progenitor.…”

“…Fission can play an important role specially when several fission cycles occur [60,96,97,98], leading to a robust r-process abundance pattern. The main fission channels include neutron induced fission, spontaneous fission, and beta-delayed fission [99,100,101,97].…”

Neutron capture on130Sn duringr-process freeze-out

“…We use β-decay rates from [44], neutron separations from [45], and neutron capture rates from [41]. Additional details of the network calculation can be found in [38]. In this initial study, as the changes to the r-process pattern occur late in the nucleosynthesis epoch, we do not include neutrino interactions other than to set the initial electron fraction.…”

“…We employ a 1D thermodynamic model of the neutrino driven wind as described in [38,39]. We choose a set of wind conditions that yield the production of r-process elements through the third peak.…”

GR effects in supernova neutrino flavor transformations

“…Prevailing understanding from the extant literature would indicate that in the case of three active flavors of neutrino emitted spherically symmetrically, one should not expect flavor transformation within the halo: if this is true then the only effect of the formation of a halo would be to alter the luminosity and angular distribution of the neutrinos beyond the photon sphere (which now becomes the effective neutrinosphere). But in other circumstances -such as calculations that include sterile neutrinos [52][53][54][55][56] or calculations with non-standard neutrino interactions [44,[57][58][59] -flavor transformation can occur much closer to the neutrinosphere in which case the formation of a halo may have greater consequences.…”