The impact of asymmetric neutrino emissions on nucleosynthesis in core-collapse supernovae II -- progenitor dependences --

TL;DR

This study explores how asymmetric neutrino emissions in core-collapse supernovae influence nucleosynthesis, showing significant effects on heavy element abundances and potential observational signatures in supernova remnants.

Contribution

It introduces axisymmetric simulations with dipolar neutrino emission asymmetries and evaluates their impact on ejecta composition across different progenitor masses.

Findings

Asymmetric neutrino emissions cause hemispheric differences in ejecta composition.

Heavy element abundances are significantly affected by neutrino asymmetries.

Predicted abundance ratios could be observed in supernova remnants.

Abstract

We investigate the impact of asymmetric neutrino-emissions on explosive nucleosynthesis in core-collapse supernovae (CCSNe) of progenitors with a mass range of 9.5 to 25$M_{\odot}$. We perform axisymmetric, hydrodynamic simulations of the CCSN explosion with a simplified neutrino-transport, in which anti-correlated dipolar emissions of $\nu_{\rm e}$ and ${\bar \nu}_{\rm e}$ are imposed. We then evaluate abundances and masses of the CCSN ejecta in a post-processing manner. We find that the asymmetric $\nu$-emission leads to the abundant ejection of $p$- and $n$-rich matter in the high-$\nu_{\rm e}$ and -${\bar \nu}_{\rm e}$ hemispheres, respectively. It substantially affects the abundances of the ejecta for elements heavier than Ni regardless of progenitors, although those elements lighter than Ca are less sensitive. Based on these results, we calculate the IMF-averaged abundances of the CCSN ejecta with taking into account the contribution from Type Ia SNe. For $m_{\rm asy} = 10/3\%$ and $10\%$, where $m_{\rm asy}$ denotes the asymmetric degree of the dipole components in the neutrino emissions, the averaged abundances for elements lighter than Y are comparable to those of the solar abundances, whereas those of elements heavier than Ge are overproduced in the case with $m_{\rm asy} \ge 30\%$. Our result also suggests that the effect of the asymmetric neutrino emissions is imprinted in the difference of abundance ratio of [Ni/Fe] and [Zn/Fe] between the high-$\nu_{\rm e}$ and -${\bar \nu}_{\rm e}$ hemispheres, indicating that the future spectroscopic X-ray observations of a CCSN remnant will bring evidence of the asymmetric neutrino emissions if exist.