大样本恒星演化研究组知识库

Kilonovae are optical flashes produced in the aftermath of neutron star-neutron star mergers or neutron star-black hole mergers. In this work, we use theMillennium Simulation, combined with semi-analytic galaxy formation model GABE (Galaxy Assembly with Binary Evolution) to explore the cosmic event rate of kilonovae, and the properties of their host galaxies in a cosmological context. We find that model with supernova kick velocity of V-kick = 0 km s(-1) fits the observation best, satisfying the preference for low kick velocity binary system in theoretical models. With V-kick = 0 km s(-1), the cosmic event rate of NNMs and NBMs at z = 0 are 283 and 91 Gpc(-3) yr(-1), respectively, marginally consistent with the constraint from LVC GWTC-1. For Milky Way-mass galaxies, we predict theNNMrate is 25.7(-7.1)(+59.6) Myr(-1), which is also in good agreement with the observed properties of binary neutron stars in the Milky Way. Taking all the kilonovae into account in the history of Milky Way-mass galaxies, we find that the averaged r-process elements yield (A > 79) in an NNM/NBM event should be 0.01 M-circle dot to be consistent with observation. We conclude that NGC 4993, the host galaxy of GW170817, is a typical host galaxy for NNMs. However, generally, NNMs and NBMs tend to reside in young, blue, star-forming, late-type galaxies, with stellar mass, and gaseous metallicity distribution peaking at M-* = 10(10.65)M(circle dot) and 12 + log (O/H) = 8.72 - 8.85, respectively. By exploring the connection between kilonovae and their host galaxies in the cosmological background, it is promising to constrain model better when we have more events in the forthcoming future.