Gamma-ray Deposition For Kilonovae

Direct detection of gravitational waves (GW) on Aug. 17, 2017, propagating from a binary neutron star merger, opened the era of multimessenger astronomy. The ejected material from a neutron star merger is called a “Kilonova”. The kilonova provided the evidence for the synthesis of heavy nuclei through the rapid neutron capture process or so-called r-process. Kilonovae derive their energy from radioactive decay, including γ-rays. Also, γ-ray opacity highly depends on photoionization [1]. The aim of our research is to alleviate this situation. In this regard we are using the AUTOSTRUCTURE code [2]. Here, the photoionization cross section of W II for photon energies from 10s of eV to 10 MeV is calculated and compared against available theoretical and experimental data.

This work was partially supported by NSF grant 1816984. References: [1] Barnes, J., Kasen, D., Wu, M.R. and Martinez-Pinedo, G., 2016. Radioactivity and thermalization in the ejecta of compact object mergers and their impact on kilonova light curves. The Astrophysical Journal, 829(2), p.110.[2] Badnell, N. R., “AUTOSTRUCTURE: General program for calculation of atomic and ionic properties”, Astrophysics Source Code Library, 2016. ascl:1612.014.