Speaker
Description
Core-collapse supernovae can synthesize $^{44}\rm Ti$ during the explosion via explosive Si-burning and $\alpha$-rich freeze-out. This radioactive isotope with a half-life of $\sim 60$ years is then observed in supernova remnants, particularly Cassiopeia A, by gamma-ray telescopes, such as the upcoming COSI mission. In this talk, I will discuss an alternative production site of $^{44}\rm Ti$ in core-collapse supernovae, i.e. Carbon-Oxygen shell mergers. These are mergers of the C-shell and O-shell that occur a few hours before collapse. They have very peculiar nucleosynthetic signatures, producing heavier $\alpha$-elements and destroying lighter ones, resulting in higher ratios of Ar/Ne, Si/Ne, S/Ne compared to progenitors that did not experience such mergers. I will show that these elemental ratios predicted by neutrino-driven explosion models of progenitors undergoing C-O shell mergers agree with observations of Cas-A. Then, I will discuss the production of titanium, and compare our predictions to the sensitivity of existing (NuSTAR) and future (COSI) gamma-ray telescopes.
| Career stage | Early-career researcher (within 5 years of PhD) |
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