Looking inside neutron stars: Microscopic calculations confront observations

While QCD appears not to be accurately solvable in the regime of interest for neutron star physics, microscopic calculations are feasible at both low and very high densities. In this work, we propose using the most realistic calculations in these two regimes of nuclear physics and perturbative QCD, and construct equations of state by matching the results requiring thermodynamic consistency. We find that the resulting equations of state — in contrast to several hadronic ones — are able to reproduce current observational data on neutron stars without any fine tuning, and allow stable hybrid stars with masses up to 2.1M_{sun}. Using recent observations of star radii, we perform a maximum likelihood analysis to further constrain the equation of state, and in addition show that the effects of rotation on radii and masses should not be neglected in future precision studies.

💡 Research Summary

This paper addresses the challenge of accurately solving Quantum Chromodynamics (QCD) in the density regimes relevant to neutron star physics. Despite this difficulty, microscopic calculations are feasible at both low and very high densities. The authors propose using the most realistic calculations from these two regimes of nuclear physics and perturbative QCD to construct equations of state that require thermodynamic consistency. These resulting equations of state can reproduce current observational data on neutron stars without any fine tuning and allow for stable hybrid stars with masses up to 2.1 solar masses.

The paper also utilizes recent observations of star radii to perform a maximum likelihood analysis, further constraining the equation of state. It emphasizes that rotational effects should not be neglected in future precision studies. This work represents an important step toward understanding the internal structure and physical characteristics of neutron stars, providing new insights into predicting their mass and radius through equations of state.