Neutron rich matter in the laboratory and in the heavens after GW170817

Abstract

The historic observations of the neutron star merger GW170817 advanced our understanding of r-process nucleosynthesis and the equation of state (EOS) of neutron rich matter. Simple neutrino physics suggests that supernovae are not the site of the main r-process. Instead, the very red color of the kilonova associated with GW170817 shows that neutron star (NS) mergers are an important r-process site. We now need to measure the masses and beta decay half-lives of very neutron rich heavy nuclei so that we can more accurately predict the abundances of heavy elements that are produced. This can be done with new radioactive beam accelerators such as the Facility for Rare Isotope Beams (FRIB). GW170817 provided information on the deformability of NS and the equation of state of dense matter. The PREX II experiment will measure the neutron skin of 208 Pb and help constrain the low density EOS. As the sensitivity of gravitational wave detectors improve, we expect to observe many more events. We look forward to exciting advances and surprises!

Nuclear Reactions in Astrophysics: A Review of Useful Probes for Extracting Reaction Rates

“…In an early application of the Coulomb dissociation method, there was a considerable effort in the community to extract the reaction rate for 7 Be(p, γ ) 8 B from the breakup of 8 B on Pb (60). This proton-capture reaction is key to understanding the neutrino flux produced by our sun.…”

“…The recent kilonova observation following the merging of two nearby neutron stars (GW170817) has unequivocally determined that neutron star mergers can produce elements as heavy as the lanthanides in very large amounts (4). However, as astrophysical models for these violent collisions advance, there is evidence of several phases/regions in the merger event, with different astrophysical conditions, in which nucleosynthesis could be taking place (5)(6)(7). In parallel, the progress of multidimensional models for core-collapse supernovae is still in the early stages when it comes to nucleosynthesis (8).…”

Studying the parameters of the extended σ-ω model for neutron star matter

“…Thus, the link between the symmetry energy and temperature observations of compact stars, see [19][20][21] and references therein. Most importantly, a correlation between the neutron star radius and the tidal deformability has been found in [22,23].…”

Systematic study on the quark-hadron mixed phase in compact stars

“…For example, if QM forms a two-flavor superconducting phase, the cooling history of a hybrid star with a large quark core may be consistent with the x-ray data [138]. Note that in the extreme scenario where hybrid stars are comprised almost entirely of QM in the color-flavor-locked phase, heat capacity would be too low to be consistent with observations [139,140].…”

“…Due to the uncertainties in relevant quantities, we do not know the exact values of D and C. Nevertheless, it has been estimated that ffiffiffiffi D p approximately lies in the range of (147, 270) MeV [51] and C ≲ 1.2 [52]. In this work, we adopt the parameter sets (1,140), and (1,180).…”