Production of ⁴⁴Ti and Iron-group Nuclei in the Ejecta of 3D Neutrino-driven Supernovae

Abstract

The radioactive isotopes 44Ti and 56Ni are important products of explosive nucleosynthesis, which play a key role in supernova (SN) diagnostics and have been detected in several nearby young SN remnants. However, most SN models based on nonrotating single stars predict yields of 44Ti that are much lower than the values inferred from observations. We present, for the first time, the nucleosynthesis yields from a self-consistent three-dimensional SN simulation of a ∼19 M ⊙ progenitor star that reaches an explosion energy comparable to that of SN 1987A and that covers the evolution of the neutrino-driven explosion until more than 7 s after core bounce. We find a significant enhancement of the Ti/Fe yield compared to recent spherically symmetric (1D) models and demonstrate that the long-time evolution is crucial to understanding the efficient production of 44Ti due to the nonmonotonic temperature and density history of the ejected material. Additionally, we identify characteristic signatures of the nucleosynthesis in proton-rich ejecta, in particular high yields of 45Sc and 64Zn.

Spectacular Nucleosynthesis from Early Massive Stars

“…J0931 + 0038 shows that current models of massive, metalpoor star nucleosynthesis are still quite limited, challenging the next generation of models. We suggest that J0931 + 0038 points to the inherent multidimensional nature of nucleosynthesis in massive stars, such as convective nuclear burning that likely impacts the iron peak yields (e.g., Herwig et al 2014;Woodward et al 2015;Curtis et al 2019;Fields & Couch 2020;Burrows & Vartanyan 2021;Sieverding et al 2023). We highlight rotation and jets for massive stars ∼ 80 M e and the i-process from proton ingestion in massive pair-instability supernova progenitors as fruitful paths for exploration.…”

“…such as explosion energy, remnant mass, convection, jets, and more. All of these elements are produced during explosive silicon burning, with different degrees of contribution from complete and incomplete burning and likely important 3D effects (e.g.,Curtis et al 2019;Sieverding et al 2023). J0931 + 0038 has an unusual iron group composition, showing very low [Sc, Ti, V/Fe]…”

A JWST Survey of the Supernova Remnant Cassiopeia A

“…The relative yields and distributions of elements, including radioactive nuclei freshly synthesized during the SN such as 56 Ni and 44 Ti (and their decay products) that originate from the innermost regions of the star where the explosion initiated, provide valuable constraints for these simulations (Grefenstette et al 2014(Grefenstette et al , 2017Wongwathanarat et al 2017;Fryer et al 2023;Sieverding et al 2023). Hundreds of years after the SN, these nuclei continue to reflect the physical processes dominating the physics of SN engines and probe the degree of explosion asymmetry.…”

Neutrino-driven Outflows and the Elemental Abundance Patterns of Very Metal-poor Stars

“…The trajectories were produced within a spherical steadystate wind model (Bliss et al 2018), therefore they cannot account for non-monotonic evolution. This may have an impact on the amount of matter ejected with a given pattern (Sieverding et al 2023), or even on the production of some elements by the vpprocess (Arcones et al 2012). A non-monotonic evolution may change the parameters (Y e , entropy per baryon, and expansion timescale) that are directly linked to a pattern.…”