Neutron-star radii based on realistic nuclear interactions

Abstract

The existence of neutron stars with $2M_{\odot }$ requires the strong stiffness of the equation of state (EoS) of neutron-star matter. We introduce a multi-pomeron exchange potential (MPP) working universally among 3- and 4-baryons to stiffen the EoS. Its strength is restricted by analyzing the nucleus-nucleus scattering with the G-matrix folding model. The EoSs are derived using the Brueckner-Hartree-Fock (BHF) and the cluster variational method (CVM) with the nuclear interactions ESC and AV18. The mass-radius relations are derived by solving the Tolmann-Oppenheimer-Volkoff (TOV) equation, where the maximum masses over $2M_{\odot }$ are obtained on the basis of the terrestrial data. Neutron-star radii $R$ at a typical mass $1.5M_{\odot }$ are predicted to be $12.3\sim 13.0$ km. The uncertainty of calculated radii is mainly from the ratio of 3- and 4-pomeron coupling constants, which cannot be fixed by any terrestrial experiment. Though values of $R(1.5M_{\odot })$ are not influenced by hyperon-mixing effects, finely-observed values for them indicate degrees of EoS softening by hyperon mixing in the region of $M\sim 2M_{\odot }$. If $R(1.5M_{\odot })$ is less than about 12.4 km, the softening of EoS by hyperon mixing has to be weak. Useful information can be expected by the space mission NICER offering precise measurements for neutron-star radii within $\pm 5\%$.

8 pages, 7 figures

References in corpus (6)

• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• Hyperon Puzzle: Hints from Quantum Monte Carlo Calculations
• Nuclear equation of state for core-collapse supernova simulations with realistic nuclear forces
• Hyperon mixing and universal many-body repulsion in neutron stars
• Medium effect in high-density region probed by nucleus-nucleus elastic scattering

Cited by in corpus (6)

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• The Role of Baryon Structure in Neutron Stars
• Quark-quark interaction and quark matter in neutron stars
• Locating the special point of hybrid neutron stars
• Effects of three-baryon forces on kaon condensation in hyperon-mixed matter