Exploring Composition Mixing in Kilonova Ejecta with Ray-by-ray Simulations*

Nuclear reactions, especially the r-process, are crucial for energy generation in binary neutron star merger (BNSM) ejecta, as well as in kilonova light curves and the production of heavy elements. In this talk, I will discuss how composition mixing influences nuclear reactions and the resulting observables. We use a 1-D simulation code, KNEC, coupled with an online nuclear network, SkyNet. We perform ray-by-ray simulations to account for the angular dependence of physical properties in the kilonova ejecta. I will show how electron fractions and other quantities, which control the availability of free neutrons and nuclear reaction rates, change with and without mixing. Mixing alters the abundances of some isotopes in individual rays, but the overall global abundances remain consistent with the no-mixing case. Additionally, I will highlight differences in the light curves in optical and near-infrared bands at late times. However, these differences are likely below the sensitivity of current state-of-the-art telescopes. This work shows that the global abundance patterns and light curves are robust under composition mixing and suggests that other hydrodynamical effects may be more critical for interpreting the observable properties of kilonovae.