Average speed of sound in neutron stars

Abstract

The structure of the dense-matter equation of state is essential for the phenomenology of neutron stars. In this work, I relate the thermodynamic properties to the average speed of sound in the interior of a star. I study the consequences of the vanishing of the trace anomaly. In particular, I show that if the trace anomaly vanishes in the centers of maximally massive neutron stars, the speed of sound likely exceeds its conformal value and exhibits nonmonotonic behavior. I also find that the additional assumption of positive definiteness of the trace anomaly naturally induces a local peak of the speed of sound at densities realized in the cores of neutron stars. I also reanalyze the stability condition for hybrid neutron stars. Possible implications for the dense matter equation of state and the phenomenology of neutron stars are also discussed.

matches published version

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• How the QCD trace anomaly behaves at the core of twin stars?
• Novel Scalings of Neutron Star Properties from Analyzing Dimensionless Tolman--Oppenheimer--Volkoff Equations
• Properties of the Object HESS J1731-347 as a Twin Compact Star
• Application of Kaluza-Klein Theory in Modeling Compact Stars: Exploring Extra Dimensions
• String-based model with Hagedorn temperature of $T_H\sim 300$MeV describes the spectrum of mesons and glueballs
• Is The Trace Anomaly at its Minimum Value at Neutron Star Centers?
• Bayesian Constraints on the Neutron Star Equation of State with a Smooth Hadron-Quark Crossover