Do varying levels of neutron richness account for the actinide boost?

T. Sprouse and M. Mumpower

Low-entropy dynamical (tidal) ejecta of a NSM

(Korobkin+ 2012; Rosswog+ 2013)

Vary the initial electron fraction: $Y_e=0.005 - 0.250$

$Y_e$ = 0: all neutrons

$Y_e$ = 1: all protons

232-Th and 238-U are radioactive

Allows radioactive decay dating

$$ t = 46.67~\text{Gyr} \left[\log\epsilon\left(\text{Th/Eu}\right)_0 - \log\epsilon\left(\text{Th/Eu}\right)_{\text{obs}}\right] $$

$$ t = 14.84~\text{Gyr} \left[\log\epsilon\left(\text{U/Eu}\right)_0 - \log\epsilon\left(\text{U/Eu}\right)_{\text{obs}}\right] $$

$$ t = 21.80~\text{Gyr} \left[\log\epsilon\left(\text{U/Th}\right)_0 - \log\epsilon\left(\text{U/Th}\right)_{\text{obs}}\right] $$

Need a method to dilute the actinides

Tidal ejecta centered at $Y_e=0.16$

(Bovard+ 2017)

Wind centered at $Y_e=0.22$

(Lippuner+ 2017)

$m_{\rm wind}/m_{\rm dyn}= 3$

(Rosswog+ 2017; Tanaka+ 2017)