Sound velocity bound and neutron stars

Abstract

It has been conjectured that the velocity of sound in any medium is smaller than the velocity of light in vacuum divided by $\sqrt{3}$. Simple arguments support this bound in non-relativistic and/or weakly coupled theories. The bound has been demonstrated in several classes of strongly coupled theories with gravity duals and is saturated only in conformal theories. We point out that the existence of neutron stars with masses around two solar masses combined with the knowledge of the equation of state of hadronic matter at "low" densities is in strong tension with this bound.

arXiv comment5 pages, 2 figures

References in corpus (28)

• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• The QCD equation of state with dynamical quarks
• The Nuclear Equation of State and Neutron Star Masses
• On Renormalization Group Flows in Four Dimensions
• Equation of state and neutron star properties constrained by nuclear physics and observation
• Effective Field Theory for Few-Nucleon Systems
• QCD at finite isospin density
• Constraining the Symmetry Parameters of the Nuclear Interaction
• The maximum mass and radius of neutron stars and the nuclear symmetry energy
• The Neutron Star Mass-Radius Relation and the Equation of State of Dense Matter
• Chiral three-nucleon forces and neutron matter
• Generic conditions for stable hybrid stars
• Constraints on neutron star radii based on chiral effective field theory interactions
• Thermodynamics of the brane
• Connecting Neutron Star Observations to Three-Body Forces in Neutron Matter and to the Nuclear Symmetry Energy
• Systematic and statistical errors in a bayesian approach to the estimation of the neutron-star equation of state using advanced gravitational wave detectors
• Constraints on the Symmetry Energy Using the Mass-Radius Relation of Neutron Stars
• Neutron Star Masses and Radii from Quiescent Low-Mass X-ray Binaries
• Nuclear energy density optimization: Shell structure
• Improved Mass and Radius Constraints for Quiescent Neutron Stars in Omega Cen and NGC 6397
• Sound waves in strongly coupled non-conformal gauge theory plasma
• Upper Limit Set by Causality on the Rotation and Mass of Uniformly Rotating Relativistic Stars
• The equation of state of neutron matter, symmetry energy, and neutron star structure
• A bound on the speed of sound from holography
• Hydrodynamics of Sakai-Sugimoto model in the quenched approximation
• Holography and the speed of sound at high temperatures
• New Constraints on Chiral Gauge Theories

Cited by in corpus (224)

• Stringent constraints on neutron-star radii from multimessenger observations and nuclear theory
• Constraining the speed of sound inside neutron stars with chiral effective field theory interactions and observations
• Nonparametric constraints on neutron star matter with existing and upcoming gravitational wave and pulsar observations
• Quarkyonic Matter and Neutron Stars
• Properties of hot and dense matter from relativistic heavy ion collisions
• How well do we know the neutron-matter equation of state at the densities inside neutron stars? A Bayesian approach with correlated uncertainties
• Neutron star tidal deformability and equation of state constraints
• Evidence for a maximum mass cut-off in the neutron star mass distribution and constraints on the equation of state
• Gravitational waves from neutron star mergers and their relation to the nuclear equation of state
• On the Sound Speed in Neutron Stars
• Impact of the PSR J0740+6620 radius constraint on the properties of high-density matter
• Towards Understanding Astrophysical Effects of Nuclear Symmetry Energy
• Dense Nuclear Matter Equation of State from Heavy-Ion Collisions
• The equation of state for dense nucleonic matter from a meta-modeling. II. Predictions for neutron stars properties
• Equation of state sensitivities when inferring neutron star and dense matter properties
• Limiting masses and radii of neutron stars and their implications
• Trace anomaly as signature of conformality in neutron stars
• Tidal deformability with sharp phase transitions in (binary) neutron stars
• Neutron Star Equation of State in light of GW190814
• Three-Nucleon Forces: Implementation and Applications to Atomic Nuclei and Dense Matter
• Constraining and applying a generic high-density equation of state
• Effects of dark matter on the nuclear and neutron star matter
• Mapping neutron star data to the equation of state using the deep neural network
• Neutron Star Radii, Universal Relations, and the Role of Prior Distributions
• Symmetric nuclear matter from the strong interaction
• Dynamical Derivation of the Momentum Space Shell Structure for Quarkyonic Matter
• Bayesian modeling of the nuclear equation of state for neutron star tidal deformabilities and GW170817
• Holographic quark matter and neutron stars
• Hot and dense quark-gluon plasma thermodynamics from holographic black holes
• PSR J0030+0451, GW170817 and the nuclear data: joint constraints on equation of state and bulk properties of neutron stars
• Relativistic description of dense matter equation of state and compatibility with neutron star observables: a Bayesian approach
• Holographic Axion Model: a simple gravitational tool for quantum matter
• Stellar properties and nuclear matter constraints
• Cool baryon and quark matter in holographic QCD
• Holographic QCD in the Veneziano limit and neutron stars
• Dark Sector to Restore Cosmological Concordance
• Extreme Matter meets Extreme Gravity: Ultra-heavy neutron stars with crossovers and first-order phase transitions
• Bayesian analysis of neutron-star properties with parameterized equations of state: the role of the likelihood functions
• Equation of state constraints from nuclear physics, neutron star masses, and future moment of inertia measurements
• Scale-Invariant Hidden Local Symmetry, Topology Change and Dense Baryonic Matter II
• Breaking the sound barrier in AdS/CFT
• Signatures for quark matter from multi-messenger observations
• Inference of the sound speed and related properties of neutron stars
• A general, scale-independent description of the sound speed in neutron stars
• Characteristics of hybrid compact stars with a sharp hadron-quark interface
• Holographic modeling of nuclear matter and neutron stars
• Bounds on the speed of sound in dense matter, and neutron star structure
• Quark-nuclear hybrid equation of state for neutron stars under modern observational constraints
• Hybrid and quark star matter based on a non-perturbative equation of state
• Unified weak/strong coupling framework for nuclear matter and neutron stars
• Plausible presence of new state in neutron stars with masses above $0.98M_{\mathrm{TOV}}$
• Hot QCD Phase Diagram From Holographic Einstein-Maxwell-Dilaton Models
• Delta baryons and diquark formation in the cores of neutron stars
• Hot quark matter and (proto-) neutron stars
• Future Physics Perspectives on the Equation of State from Heavy Ion Collisions to Neutron Stars
• Stiffening of matter in quark-hadron continuity
• Far-from-equilibrium search for the QCD critical point
• Extensive Studies of the Neutron Star Equation of State from the Deep Learning Inference with the Observational Data Augmentation
• Impact of large-mass constraints on the properties of neutron stars
• g-mode Oscillations in Hybrid Stars: A Tale of Two Sounds
• Large Sound Speed in Dense Matter and the Deformability of Neutron Stars
• The slope, the hill, the drop, and the swoosh: Learning about the nuclear matter equation of state from the binary Love relations
• Relativistic mean-field theories for neutron-star physics based on chiral effective field theory
• The effect of $f(R,T)$ modified gravity on mass and radius of pulsar HerX1
• Deconfined, Massive Quark Phase at High Density and Compact Stars: A Holographic Study
• Hydrodynamics of phase transition fronts and the speed of sound in the plasma
• QCD color superconductivity in compact stars: color-flavor locked quark star candidate for the gravitational-wave signal GW190814
• Merger of compact stars in the two-families scenario
• Constraining hadron-quark phase transition parameters within the quark-mean-field model using multimessenger observations of neutron stars
• Speed of sound constraints from tidal deformability of neutron stars
• Phase Transition Phenomenology with Nonparametric Representations of the Neutron Star Equation of State
• Bayesian inference of strange star equation of state using the GW170817 and GW190425 data
• Excluded-volume model for quarkyonic Matter: Three-flavor baryon-quark Mixture
• Sensitivity of Au+Au collisions to the symmetric nuclear matter equation of state at 2 -- 5 nuclear saturation densities
• Phase transitions and critical behavior in hadronic transport with a relativistic density functional equation of state
• On the minimum radius of very massive neutron stars
• On the maximum mass limit of neutron stars in scalar-tensor gravity
• Quarkyonic stars with isospin-flavor asymmetry
• The role of strangeness in hybrid stars and possible observables
• Bayesian nonparametric inference of neutron star equation of state via neural network
• Constraining the neutron-matter equation of state with gravitational waves
• Momentum Shell in Quarkyonic Matter from Explicit Duality: A Dual Model for Cold, Dense QCD
• Speed of sound from fundamental physical constants
• On the nature of the mass-gap object in the GW190814 event
• Stiff phases in strongly coupled gauge theories with holographic duals
• The high-density equation of state in heavy-ion collisions: Constraints from proton flow
• Large and massive neutron stars: Implications for the sound speed in dense QCD
• Colour-Flavour Locked Quark Stars in Light of the Compact Object in HESS J1731-347 and the GW190814 Event
• Remarks on nuclear matter: how an ${\omega }_0$ condensate can spike the speed of sound, and a model of $Z(3)$ baryons
• Constraints on the phase transition and nuclear symmetry parameters from PSR $\mathrm{J}0740+6620$ and multimessenger data of other neutron stars
• Predicting the moment of inertia of pulsar J0737-3039A from Bayesian modeling of the nuclear equation of state
• Speed of sound and baryon cumulants in heavy-ion collisions
• Probing Quarkyonic Matter in Neutron Stars with the Bayesian Nuclear-Physics Multi-Messenger Astrophysics Framework
• Universal Bounds on Transport in Holographic Systems with Broken Translations
• From the microscopic to the macroscopic world: from nucleons to neutron stars
• Bayesian inference of signatures of hyperons inside neutron stars
• Excluded-volume model for quarkyonic matter II: Three-flavor shell-like distribution of baryons in phase space
• Confront $f(R,T)=\mathcal{R}+\beta T$ modified gravity with the massive pulsar PSR J0740+6620
• Quark Models and Radial Oscillations: Decoding the HESS J1731-347 Compact Object's Equation of State
• Sound velocity in dense stellar matter with strangeness and compact stars
• A model-agnostic analysis of hybrid stars with reactive interfaces
• Neutron star collapse and gravitational waves with a non-convex equation of state
• Interacting $ud$ and $uds$ quark matter at finite densities and quark stars
• Equation of state of cold and dense QCD matter in resummed perturbation theory
• GW190814: Circumstantial Evidence for Up-Down Quark Star
• Trace of the energy-momentum tensor and macroscopic properties of neutron stars
• Sound velocity peak and conformality in isospin QCD
• Insights on the peak in the speed of sound of ultradense matter
• nEoS: Neutron Star Equation of State from hadron physics alone
• Effects of $\varphi$-meson on properties of hyperon stars in density dependent relativistic mean field model
• Sound velocity and tidal deformability in compact stars
• Universal Formula for the Holographic Speed of Sound
• Two first-order phase transitions in hybrid compact stars: higher-order multiplet stars, reaction modes and intermediate conversion speeds
• Phenomenological QCD equations of state for neutron star dynamics: Nuclear-2SC continuity and evolving effective couplings
• Bayesian refinement of covariant energy density functionals
• A pseudo-conformal structure in dense baryonic matter
• Speed of sound constraints on maximally rotating neutron stars
• Structure in the speed of sound: from neutron stars to heavy-ion collisions
• Structure of Quark Star: A Comparative Analysis of Bayesian Inference and Neural Network Based Modeling
• Mass and radius relations of quarkyonic stars using an excluded volume model
• Hadron matter in neutron stars in view of gravitational wave observations
• Implications of the Conformal Constraint on Sound Speed on the Radius of PSR J0952-0607 within Rastall Gravity
• Delta baryons in neutron stars
• Nuclear matter fourth-order symmetry energy in non-relativistic mean-field models
• Equation-of-state-insensitive measure of neutron star stiffness
• Hot and Dense Homogeneous Nucleonic Matter Constrained by Observations, Experiment, and Theory
• Neutron stars and phase diagram in a hard-wall AdS/QCD model
• Searching for New Physics in Ultradense Environment: a Review on Dark Matter Admixed Neutron Stars
• From quarks and gluons to color superconductivity at supranuclear densities
• Radial Oscillations in Neutron Stars with Delta Baryons
• Hypernuclei and the hyperon problem in neutron stars
• Speed of sound and quark confinement inside neutron stars
• Symmetry energy and neutron star properties constrained by chiral effective field theory calculations
• Central Speed of Sound, Trace Anomaly and Observables of Neutron Stars from Perturbative Analyses of Scaled TOV Equations
• Effect of nuclear saturation parameters on possible maximum mass of neutron stars
• Topology and emergent symmetries in dense compact star matter
• Speed of sound in dense matter and two families of compact stars
• How the QCD trace anomaly behaves at the core of twin stars?
• Highly compact neutron stars and screening mechanisms. I. Equilibrium and stability
• Core States of Neutron Stars from Anatomizing their Scaled Structure Equations
• Speed of sound in dense strong-interaction matter
• Gluon effects on the equation of state of color superconducting strange stars
• Pressure and speed of sound in two-flavor color-superconducting quark matter at next-to-leading order
• The interplay of astrophysics and nuclear physics in determining the properties of neutron stars
• A Bayesian study of quark models in view of recent astrophysical constraints
• Causality violation and the speed of sound of hot and dense quark matter in the Nambu--Jona-Lasinio model
• Speed of Sound for Hadronic and Quark Phases in a Magnetic Field
• The impact of quark masses on pQCD thermodynamics
• Analyzing the speed of sound in neutron star with machine learning
• Holographic cold dense matter constrained by neutron stars
• Bayesian constraints on covariant density functional equations of state of compact stars with new NICER mass-radius measurements
• Radial oscillations in neutron stars from QCD
• Speed of sound bounds and first-order phase transitions in compact stars
• Novel Scalings of Neutron Star Properties from Analyzing Dimensionless Tolman--Oppenheimer--Volkoff Equations
• I-Love-Q to the extreme
• Bayesian Inference of dense matter equation of state of neutron star with antikaon condensation
• Hybrid Stars Built with Density Dependent Models
• Properties of First-Order Hadron-Quark Phase Transition from Inverting Neutron Star Observables
• Decoding the flow evolution in Au+Au reactions at $1.23A$ GeV using hadron flow correlations and dileptons
• Properties of condensed matter from fundamental physical constants
• Aspects of univalence in holographic axion models
• Prospect of unraveling the first-order phase transition in neutron stars with $f$ and $p_1$ modes
• Constraining Quadratic $f(R)$ Gravity from Astrophysical Observations of the Pulsar J0704+6620
• Scale symmetry and composition of compact star matter
• Quarkyonic Mean Field Theory
• Gravitational-wave imprints of non-convex dynamics in binary neutron star mergers
• Anomalous dynamics triggered by a non-convex equation of state in relativistic flows
• Hyperons, deconfinement and the speed of sound in neutron stars
• Constraining Palatini gravity with GR-independent equations of state for neutron stars
• Comparison of different relativistic models applied to dense nuclear matter
• Neutron Stars and Gravitational Waves: the Key Role of Nuclear Equation of State
• Equation of State of Neutron-Rich Matter in $d$-Dimensions
• Analyzing the dense matter equation of states in the light of the compact object HESS J1731-347
• Delineating chiral separation effect in two-color dense QCD
• Holography with a Landau pole
• The remnant of GW170817: a trapped neutron star with a hypermassive incompressible superfluid core
• Relativistic stellar modeling with perfect fluid core and anisotropic envelope fluid
• Strong Gravity Extruding Peaks in Speed of Sound Profiles of Massive Neutron Stars
• The equation of state in two-, three-, and four-color QCD at non-zero temperature and density
• Equation of state of asymmetric nuclear matter and the tidal deformability of neutron star
• Quark matter with strong magnetic field and possibility of the third family of compact stars
• Conditions for the existence of stable strange quark matter
• Composition of scalar mesons and their effects on nuclear matter properties in an extended linear sigma model
• Upper Limit of Sound Speed in Nuclear Matter: A Harmonious Interplay of Transport Calculation and Perturbative Quantum Chromodynamic Constraint
• Unraveling Trace Anomaly of Supradense Matter via Neutron Star Compactness Scaling
• Tangled magnetic field model of QPOs
• Strangeness thermodynamic instabilities in hot and dense nuclear matter
• Neutron-quark stars: Discerning viable alternatives for the higher-density part of the equation of state of compact stars
• Neutron stars in the large-$N_c$ limit
• Gravo-thermal catastrophe in gravitational collapse and energy progenitor of Gamma-Ray Bursts
• Fundamental Oscillation Modes in Neutron Stars with Hyperons and Delta Baryons
• Speed of sound peak in isospin QCD: a natural prediction of the Medium Separation Scheme
• Thermal phonon fluctuations and stability of the magnetic dual chiral density wave phase in dense QCD
• Non-Radial Oscillation Modes in Hybrid Stars with Hyperons and Delta Baryons
• Axion-Polaritons in quark stars: a possible solution to the missing pulsar problem
• Investigating the Impact of Higher-Order Phase Transitions in Binary Neutron-Star Mergers
• Properties of compact objects in quadratic non-metricity gravity
• Love-C relations for elastic hybrid stars
• Exploring Radial Oscillations in Slow Stable and Hybrid Neutron Stars
• Dense matter equation of state and neutron star properties from nuclear theory and experiment
• Equation of state for hyperonic neutron-star matter in SU(3) flavor symmetry
• Density Functional Equation of State and Its Application to the Phenomenology of Heavy-Ion Collisions
• Towards a holographic quark-hadron continuity
• Analytical model on mass limit of strange stars
• The "Folk Theorem" on Effective Field Theory: How Does It Fare in Nuclear Physics?
• How Neutron Star Observations Point Towards Exotic Matter: Existing Explanations and a Prospective Proposal
• Thermodynamic properties of non-Hermitian Nambu--Jona-Lasinio models
• Exceeding the conformal limit inside rotating neutron stars: Implications to modified theories of gravity
• Wheeler-DeWitt Universe Wave Function in the presence of stiff matter
• Is The Trace Anomaly at its Minimum Value at Neutron Star Centers?
• Numerical evaluation of the exact post-Newtonian parameters in Brans-Dicke and entangled relativity theories
• Nonlinear analysis of causality for heat flow in heavy-ion collisions: constraints from equation of state
• Observability of sharp phase transitions in neutron stars
• Effects of a Brueckner-Hartree-Fock-corrected effective mass on speed of sound, conformality, and observables of dark matter-admixed neutron stars
• Impact of hyperons on structural properties of neutron stars and hybrid stars within the regularized four-dimensional Einstein-Gauss-Bonnet gravity
• Neutron stars as extreme gravity probes
• From pQCD to neutron stars: matching equations of state to constrain global star properties
• Examining the possibility of a thick crust in the compact stellar object HESS J1731-347
• Unified nonparametric equation-of-state inference from the neutron-star crust to perturbative-QCD densities
• Tracing the Trace Anomaly of Dense Matter inside Neutron Stars
• Recurring region for neutron-star observables
• Holography in Quark-Gluon Plasma and Neutron Stars
• Bayesian Constraints on the Neutron Star Equation of State with a Smooth Hadron-Quark Crossover
• Finite density nuclear matter and neutron stars in hard-wall AdS/QCD model