http://arxiv.org/abs/2102.10074
The symmetry energy and its density dependence are crucial inputs for many nuclear physics and astrophysics applications, as they determine properties ranging from the neutron-skin thickness of nuclei to the crust thickness and the radius of neutron stars. Recently, PREX-II reported a value of $0.29\pm 0.07$ fm for the neutron-skin thickness of $^{208}$Pb, implying a slope parameter $L = 110\pm 37$ MeV, larger than most ranges obtained from microscopic calculations and other nuclear experiments. We use a nonparametric equation of state representation based on Gaussian processes to constrain the symmetry energy $S_0$, $L$, and $R_{\rm skin}^{^{208}\text{Pb}}$ directly from observations of neutron stars with minimal modeling assumptions. The resulting astrophysical constraints from heavy pulsar masses, LIGO/Virgo, and NICER clearly favor smaller values of the neutron skin and $L$, as well as negative symmetry incompressibilities. Combining astrophysical data with PREX-II and chiral effective field theory constraints yields $S_0 = 34^{+3}{-3}$ MeV, $L=58^{+19}{-19}$ MeV, and $R_{\rm skin}^{^{208}\text{Pb}} = 0.19^{+0.03}_{-0.04}$ fm.
R. Essick, I. Tews, P. Landry, et. al.
Mon, 22 Feb 21
24/51
Comments: 7 pages, 4 figures, 1 table