Speaker
Michael Famiano
Description
If an astrophysical environment is hot enough (greater than approximately 0.5 MeV or so), screening in the associated nuclear reactions can be modifed by the presence of a relativistic electron-positron plasma. For non-zero electron chemical potentials, the effect is compounded as the relativistic Debye length in a plasma can be much lower than the classical Debye length. The screening is then enhanced beyond the commonly used classical approximation. This can result in a further enhancement of nuclear reaction rates, and the reaction rate enhancement factor is studied in several relevant scenarios. For sub- or near-threshold resonances, this could potentially change the reaction rates by a significant amount as the reaction energy effectively shifts the resonance above or below threshold. Possible sites where relativistic plasma screening could have a significant effect on results include Big Bang Nucleosynthesis, alpha-rich freezout in the r-process, x-ray bursts, type Ia supernovae, and late-stage burning in massive stellar cores. Current results will be presented in which relativistic plasma effects in high-temperature and high-density environments have been studied. In addition, plasma screening is extended into the intermediate screening regime by exploring higher-order terms in the Poisson-Boltzmann equation.
