Equation-of-state-insensitive measure of neutron star stiffness

Abstract

Universal relations (i.e., insensitive to the equation of state) between macroscopic properties of neutron stars have proven useful for a variety of applications -- from providing a direct means to extract observables from data to breaking degeneracies that hinder tests of general relativity. Similarly, equation-of-state-insensitive relations directly connecting macroscopic and microscopic properties of neutron stars can potentially provide a clean window into the behavior of nuclear matter. In this work, we uncover a tight correlation between certain macroscopic properties of a neutron star - its compactness $C$, moment of inertia $\bar{I}$ and tidal deformability $\bar{\Lambda }$ - and the ratio ${\alpha }_c\equiv p_c/{\epsilon }_c$ of central pressure to central energy density, which can be interpreted as a mean notion of the stiffness of nuclear matter inside that object. We describe interesting properties of this stiffness measure, quantify the (approximate) universality of the ${\alpha }_c-C/\bar{I}/\bar{\Lambda }$ relations, and explore its consequences in the face of recent and future neutron star observations.

10 pages, 9 figures; extended and revised to match published version

References in corpus (21)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Multi-messenger Observations of a Binary Neutron Star Merger
• PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter
• A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation
• Tidal Love numbers of neutron stars
• A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy
• Tests of general relativity from timing the double pulsar
• Refined Mass and Geometric Measurements of the High-Mass PSR J0740+6620
• Constraints on a phenomenologically parameterized neutron-star equation of state
• Relativistic theory of tidal Love numbers
• Timing Measurements of the Relativistic Binary Pulsar PSR B1913+16
• Sound velocity bound and neutron stars
• Constraints on the Symmetry Energy Using the Mass-Radius Relation of Neutron Stars
• Spectral Representations of Neutron-Star Equations of State
• Chiral Effective Field Theory and the High-Density Nuclear Equation of State
• Prospects For High Frequency Burst Searches Following Binary Neutron Star Coalescence With Advanced Gravitational Wave Detectors
• A Parametrized Equation of State for Neutron Star Matter with Continuous Sound Speed
• Updated universal relations for tidal deformabilities of neutron stars from phenomenological equations of state
• The onset of spontaneous scalarization in generalised scalar-tensor theories
• The Radius of PSR J0740+6620 from NICER and XMM-Newton Data
• Highly compact neutron stars and screening mechanisms. I. Equilibrium and stability

Cited by in corpus (1)

• Systematic errors due to quasi-universal relations in binary neutron stars and their correction for unbiased model selection