Constraints on the muon fraction and density profile in neutron stars

Abstract

Muons in neutron stars (NSs) play especially important roles in addressing several interesting new physics questions associated with detecting as well as understanding interactions and astrophysical effects of muonphilic dark matter particles. The key model inputs for studying the latter are the total muon mass $M_{\mu }$, the muon mass fraction $M_{\mu }/M_{\mathrm{NS}}$ over the NS mass $M_{\mathrm{NS}}$ and the muon radial density profile ${\rho }_{\mu }(r)$ in NSs of varying masses. We investigate these quantities within a minimum model for the core of NSs consisting of neutrons, protons, electrons, and muons using an explicitly isospin-dependent parametric Equation of State (EOS) constrained by available nuclear laboratory experiments and the latest astrophysical observations of NS masses, radii and tidal deformabilities. We found that the absolutely maximum muon mass $M_{\mu }$ and its mass fraction $M_{\mu }/M_{\mathrm{NS}}$ in the most massive NSs allowed by causality are about 0.025 $M_{\odot }$ and 1.1\%, respectively. For the most massive NS of mass 2.14 $M_{\odot }$ observed so far, they reduce to about 0.020 $M_{\odot }$ and 0.9\%, respectively. We also study respective effects of individual parameters describing the EOS of high-density neutron-rich nucleonic matter on the muon contents in NSs with varying masses. We found that the most important but uncertain nuclear physics ingredient for determining the muon contents in NSs is the high-density nuclear symmetry energy.

arXiv commentAdded more discussions and references. The Astrophysical Journal (2020) in press

References in corpus (47)

• GW170817: Measurements of Neutron Star Radii and Equation of State
• 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
• Relativistic Shapiro delay measurements of an extremely massive millisecond pulsar
• Recent Progress and New Challenges in Isospin Physics with Heavy-Ion Reactions
• Equations of state for supernovae and compact stars
• The Equation of State from Observed Masses and Radii of Neutron Stars
• Strange Quark Matter and Compact Stars
• Reaction Dynamics with Exotic Beams
• Phase Transitions in Warm, Asymmetric Nuclear Matter
• Constraining the neutron-proton effective mass splitting using empirical constraints on the density dependence of nuclear symmetry energy around normal density
• Isospin Fractionation in Nuclear Multifragmentation
• Symmetry Parameter Constraints From A Lower Bound On The Neutron-Matter Energy
• A NICER view of PSR J0030+0451: Implications for the dense matter equation of state
• Constraints on the Symmetry Energy Using the Mass-Radius Relation of Neutron Stars
• Towards Understanding Astrophysical Effects of Nuclear Symmetry Energy
• Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. I. The Millisecond Pulsar X-ray Data Set
• Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. II. Emission from Hot Spots on a Rapidly Rotating Neutron Star
• Combined Constraints on the Equation of State of Dense Neutron-Rich Matter from Terrestrial Experiments and Observations of Neutron Stars
• Hadron-Quark Crossover and Massive Hybrid Stars
• A NICER view of PSR J0030+0451: evidence for a global-scale multipolar magnetic field
• Constraining the Radii of Neutron Stars with Terrestrial Nuclear Laboratory Data
• Do we understand the incompressibility of neutron-rich matter?
• Extracting Nuclear Symmetry Energies at High Densities from Observations of Neutron Stars and Gravitational Waves
• Bayesian Inference of High-density Nuclear Symmetry Energy from Radii of Canonical Neutron Stars
• Capture of Leptophilic Dark Matter in Neutron Stars
• Critical Density and Impact of $\Delta (1232)$ Resonance Formation in Neutron Stars
• Dark matter interactions with muons in neutron stars
• Nuclear Theory and Science of the Facility for Rare Isotope Beams
• Implications of the mass $M=2.17_{-0.10}^{+0.11}$M${}_{\odot }$ of PSR~J0740+6620 on the Equation of State of Super-Dense Neutron-Rich Nuclear Matter
• NICER X-ray Observations of Seven Nearby Rotation-Powered Millisecond Pulsars
• Interplay between $\Delta$ Particles and Hyperons in Neutron Stars
• Hyperonic stars and the symmetry energy
• How tightly is nuclear symmetry energy constrained by unitary Fermi gas?
• $\Delta$ (1232) effects in density-dependent relativistic Hartree-Fock theory and neutron stars
• Equation of state of dense matter in the multimessenger era
• Delineating Effects of Nuclear Symmetry Energy on the Radii and Tidal Polarizabilities of Neutron Stars
• Constraints on Skyrme Equations of State from Properties of Doubly Magic Nuclei and Ab-Initio Calculations of Low-Density Neutron Matter
• New constraints on the nuclear equation of state from the thermal emission of neutron stars in quiescent low-mass X-ray binaries
• Constraining compact star properties with nuclear saturation parameters
• Cooling timescale for protoneutron stars and properties of nuclear matter: Effective mass and symmetry energy at high densities
• Microscopic study of neutrino trapping in hyperon stars
• Neutron star matter with strange interactions in a relativistic quark model
• Constraining the neutron star equation of state using Pulse Profile Modeling
• Catalysis of partial chiral symmetry restoration by Delta matter
• Ruling out the supersoft high-density symmetry energy from the discovery of PSR J0740+6620 with mass $2.14_{-0.09}^{+0.10}{M}_{\odot }$
• Hyperons in Neutron Stars

Cited by in corpus (17)

• A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy
• Progress in Constraining Nuclear Symmetry Energy Using Neutron Star Observables Since GW170817
• GW190814's secondary component with mass $(2.50-2.67)$ M${}_{\odot }$ as a super-fast pulsar
• Bayesian Inference of the Symmetry Energy of Super-Dense Neutron-Rich Matter from Future Radius Measurements of Massive Neutron Stars
• Bayesian inference of dense matter EOS encapsulating a first-order hadron-quark phase transition from observables of canonical neutron stars
• Curvature-slope correlation of nuclear symmetry energy and its imprints on the crust-core transition, radius and tidal deformability of canonical neutron stars
• Impact of NICER's Radius Measurement of PSR J0740+6620 on Nuclear Symmetry Energy at Suprasaturation Densities
• The Radius of PSR J0740+6620 from NICER and XMM-Newton Data
• Bayesian Inference of Fine-Features of Nuclear Equation of State from Future Neutron Star Radius Measurements to 0.1km Accuracy
• Empirical radius formulas for canonical neutron stars from bidirectionally selecting EOS features in extended Bayesian analyses of observational data
• Properties of First-Order Hadron-Quark Phase Transition from Inverting Neutron Star Observables
• Impact of the nuclear equation of state on the formation of twin stars
• Leptonic and semi-leptonic neutrino interactions with muons in the proto-neutron star cooling
• Illuminating dark matter admixed in neutron stars with simultaneous mass-radius constraints
• Imprints of high-density nuclear symmetry energy on the crustal fraction of neutron star moment of inertia
• Constraining Fundamental Constant Variations from Ultralight Dark Matter with Pulsar Timing Arrays
• Unified Equation of State for Neutron Stars Based on the Gogny Interaction