Speaker
Description
In 2017 the first neutron star merger was observed at LIGO, and for a neutron star binary system to merge within a hubble time the progenitor system must undergo a common envelope phase to dissipate the orbital energy and bring the two compact masses closer together [1]. During the common envelope phase the compact neutron star orbits within the envelope of the companion star and accretes material from the companion onto the neutron star surface. During this accretion a disk will form around the neutron star in which material is heated to extreme temperatures, providing an area for high energy nucleosynthesis to occur. A fraction of the accreted material is then mixed back into the shared envelope, which is then ejected into the interstellar medium at the end of the common envelope phase. An initial investigation into the ejection mechanism when material is in free fall towards the neutron star was conducted by Keegans et al. [2019] [2] and showed evidence of proton rich nucleosynthesis occuring during accretion. The work presented in this talk will show how the nucleosynthesis varies when using more realistic trajectories, which include the effects of angular momentum. I will also present results from a range of different neutron star common envelope binaries in which the accretion rate, neutron star mass, companion mass, and companion age are varied.
[1] Dominik, M., Belczynski, K., Fryer, C., Holz, D.E., Berti, E., Bulik, T., Mandel, I. and O'shaughnessy, R., 2012. Double compact objects. I. The significance of the common envelope on merger rates. The Astrophysical Journal, 759(1), p.52.
[2] Keegans, J., Fryer, C.L., Jones, S.W., Côté, B., Belczynski, K., Herwig, F., Pignatari, M., Laird, A.M. and Diget, C.A., 2019. Nucleosynthetic yields from neutron stars accreting in binary common envelopes. Monthly Notices of the Royal Astronomical Society, 485(1), pp.620-639.
