Speaker
Dr
Farrukh Fattoyev
(Indiana University)
Description
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⊙ neutron star of R1.4 < 13.76 km. Given the sensitivity of the neutron-skin thickness of 208Pb to the symmetry energy, albeit at a lower density, we infer a corresponding upper limit of about R208 <= 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.
Primary author
Charles Horowitz
(Indiana University)
Co-authors
Dr
Farrukh Fattoyev
(Indiana University)
Jorge Piekarewicz
(Florida State University)