The historical first detection of a binary neutron star merger by the LIGO-Virgo collaboration [ B. P. Abbott et al . Phys .
Rev .
Lett .
119 , 161101 ( 2017 ) ] is providing fundamental new insights into the astrophysical site for the r -process and on the nature of dense matter .
A set of realistic models of the equation of state ( EOS ) that yield an accurate description of the properties of finite nuclei , support neutron stars of two solar masses , and provide a Lorentz covariant extrapolation to dense matter are used to confront its predictions against tidal polarizabilities extracted from the gravitational-wave data .
Given the sensitivity of the gravitational-wave signal to the underlying EOS , limits on the tidal polarizability inferred from the observation translate into constraints on the neutron-star radius .
Based on these constraints , models that predict a stiff symmetry energy , and thus large stellar radii , can be ruled out .
Indeed , we deduce an upper limit on the radius of a 1.4 M _ { \odot } neutron star of R _ { \star } ^ { 1.4 } < 13.76 { km } .
Given the sensitivity of the neutron-skin thickness of ^ { 208 } Pb to the symmetry energy , albeit at a lower density , we infer a corresponding upper limit of about R _ { skin } ^ { 208 } \lesssim 0.25 { fm } .
However , if the upcoming PREX-II experiment measures a significantly thicker skin , this may be evidence of a softening of the symmetry energy at high densities—likely indicative of a phase transition in the interior of neutron stars .