The compact object of HESS J1731-347 and its implication on neutron star matter

Abstract

In this work, we investigate the impact of the possibility of a small, subsolar mass compact star, such as the recently reported central compact object of HESS J1731-347, on the equation of state (EOS) of neutron stars. We have used a hybrid approach to the nuclear EOS developed recently where the matter around nuclear saturation density is described by a parametric expansion in terms of nuclear empirical parameters and represented in an agnostic way at higher density using piecewise polytropes. We have incorporated the inputs provided by the latest neutron skin measurement experiments from PREX-II and CREX, simultaneous mass-radius measurements of pulsars PSR J0030+0451 and PSR J0740+6620, and the gravitational wave events GW170817 and GW190425. The main results of the study show the effect of HESS J1731-347 on the nuclear parameters and neutron star observables. Our analysis yields the slope of symmetry energy $L=45.71^{+38.18}_{-22.11}$ MeV, the radius of a $1.4 M_\odot$ star, $R_{1.4}=12.18^{+0.71}_{-0.88}$ km, and the maximum mass of a static star, $M_{\rm max}= 2.14^{+0.26}_{-0.17} M_\odot$ within $90\%$ confidence interval, respectively.

Figures (6)

• Figure 1: Posterior distribution of EOS parameters with their 90% CI.
• Figure 2: Posterior distribution of pressure as a function of energy density at 90 % CI. The axes are shown in the logarithmic scale.
• Figure 3: Mass-radius posteriors at 90 % CI with the EOS models shown in figure \ref{['fig:eos-post']}.
• Figure 4: Correlation plot for isovector quantities with neutron star observables with their 90% CI.
• Figure 5: Correlation plot of inferred properties of HESS J1731-347 at 90% CI.