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Hadronic description of nuclear matter and neutron star properties

Yao Ma, Yong-Liang Ma, Jia-Ying Xiong

Abstract

The composition of the neutron star is one of the most fundamental and long-standing problems in nuclear- and astro-physics. The known properties of nuclear matter, together with the astronomical observations, impose the stringent and interconnected constraints on the theoretical descriptions. In this work, by using the most general quantum hadrodynamics model including $σ, ω, ρ$ and $a_0$ in addition to nucleons, and performing a Bayesian joint analysis of experimental nuclear matter data and astrophysical observations, we point out that the nuclear matter made of only hadrons can provide a unified description of nuclear matter properties and astrophysical observations at $1 σ$-level. In addition, we find that the existence of \(σωρa_0\) interaction naturally leads to a peak structure in the speed of sound at $\sim (2-3)$ times saturation density $n_0$ which results to a small size intermediate mass neutron star and the upper bound mass $\sim 2M_\odot$. What we find here indicate that the sequential measurement of neutron star mass and radius by the next generation facilities, especially that of the intermediate mass neutron stars, is crucial for distinguishing the pure nucleonic stars from the hybrid ones.

Hadronic description of nuclear matter and neutron star properties

Abstract

The composition of the neutron star is one of the most fundamental and long-standing problems in nuclear- and astro-physics. The known properties of nuclear matter, together with the astronomical observations, impose the stringent and interconnected constraints on the theoretical descriptions. In this work, by using the most general quantum hadrodynamics model including and in addition to nucleons, and performing a Bayesian joint analysis of experimental nuclear matter data and astrophysical observations, we point out that the nuclear matter made of only hadrons can provide a unified description of nuclear matter properties and astrophysical observations at -level. In addition, we find that the existence of interaction naturally leads to a peak structure in the speed of sound at times saturation density which results to a small size intermediate mass neutron star and the upper bound mass . What we find here indicate that the sequential measurement of neutron star mass and radius by the next generation facilities, especially that of the intermediate mass neutron stars, is crucial for distinguishing the pure nucleonic stars from the hybrid ones.
Paper Structure (2 sections, 9 equations, 7 figures, 2 tables)

This paper contains 2 sections, 9 equations, 7 figures, 2 tables.

Table of Contents

  1. Appendix A. Bayesian joint analysis
  2. Appendix B. BJA and parameter space

Figures (7)

  • Figure 1: The M-R relation of TM1 Sugahara:1993wz, NL1 reinhard1986nuclear, NL3 Lalazissis:1996rd, FSU-$\delta 6.7$Li:2022okx, FSUGold Todd-Rutel:2005yzo, GWM1 and GWM2 with CBC. The constraints PSR J1614-2230, PSR J0348+0432, PSR J0740+6620, J0030+0451, PSR J0437–4715, and PSR J0614–3329, from LIGOScientific:2017vwqLIGOScientific:2017yncLIGOScientific:2018ckiSalmi:2024aumVinciguerra:2023qxqChoudhury:2024xbkMauviard:2025dmd.
  • Figure 2: Pressure as a function of density for symmetric NM. HIC constraint is from $Au+Au$ flow-data analysis Danielewicz:2002pu, $\chi EFT-N^2LO$ and $\chi EFT-N^3LO$ are from chiral nuclear force Huth:2021bsp, Kaons constraint is from Lynch:2009vcFuchs:2005zg.
  • Figure 3: The density dependence of sound velocity $v_s^2$ from different models.
  • Figure 4: Effect of the mixed $\sigma\omega\rho a_0$ coupling on the $v_s^2$.
  • Figure 5: Tidal deformability as a function of mass obtained from various models.
  • ...and 2 more figures