The I-Love-Q Relations for Superfluid Neutron Stars

Abstract

The I-Love-Q relations are approximate equation-of-state independent relations that connect the moment of inertia, the spin-induced quadrupole moment, and the tidal deformability of neutron stars. In this paper, we study the I-Love-Q relations for superfluid neutron stars for a general relativistic two-fluid model: one fluid being the neutron superfluid and the other a conglomerate of all charged components. We study to what extent the two-fluid dynamics might affect the robustness of the I-Love-Q relations by using a simple two-component polytropic model and a relativistic mean field model with entrainment for the equation-of-state. Our results depend crucially on the spin ratio ${\Omega }_{\mathrm{n}}/{\Omega }_{\mathrm{p}}$ between the angular velocities of the neutron superfluid and the normal component. We find that the I-Love-Q relations can still be satisfied to high accuracy for superfluid neutron stars as long as the two fluids are nearly co-rotating ${\Omega }_{\mathrm{n}}/{\Omega }_{\mathrm{p}}\approx 1$. However, the deviations from the I-Love-Q relations increase as the spin ratio deviates from unity. In particular, the deviation of the Q-Love relation can be as large as $O(10\%)$ if ${\Omega }_{\mathrm{n}}/{\Omega }_{\mathrm{p}}$ differ from unity by a few tens of percent. As ${\Omega }_{\mathrm{n}}/{\Omega }_{\mathrm{p}}\approx 1$ is expected for realistic neutron stars, our results suggest that the two-fluid dynamics should not affect the accuracy of any gravitational waveform models for neutron star binaries that employ the relation to connect the spin-induced quadrupole moment and the tidal deformability.

arXiv commentInvited contribution to Universe's Special Issue "Superfluidity and Superconductivity in Neutron Stars" (Guest Editor: Nicolas Chamel)

References in corpus (66)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Tidal Love numbers of neutron stars
• Gravitational-wave constraints on the neutron-star-matter Equation of State
• Relativistic tidal properties of neutron stars
• New constraints on radii and tidal deformabilities of neutron stars from GW170817
• Tidal Deformabilities and Radii of Neutron Stars from the Observation of GW170817
• I-Love-Q Relations in Neutron Stars and their Applications to Astrophysics, Gravitational Waves and Fundamental Physics
• I-Love-Q
• Neutron skins and neutron stars in the multi-messenger era
• Approximate Universal Relations for Neutron Stars and Quark Stars
• Relativistic effective interaction for nuclei, giant resonances, and neutron stars
• A critical examination of constraints on the equation of state of dense matter obtained from GW170817
• Maximum mass, moment of inertia and compactness of relativistic stars
• Models of Pulsar Glitches
• GW170817: constraining the nuclear matter equation of state from the neutron star tidal deformability
• Implications from GW170817 and I-Love-Q relations for relativistic hybrid stars
• Towards Understanding Astrophysical Effects of Nuclear Symmetry Energy
• Neutron star tidal deformabilities constrained by nuclear theory and experiment
• Superfluidity in nuclear systems and neutron stars
• Thermodynamics conditions of matter in neutron star mergers
• Differential rotation of relativistic superfluid in neutron stars
• Inferring physical parameters of compact stars from their f-mode gravitational wave signals
• Effectively universal behavior of rotating neutron stars in general relativity makes them even simpler than their Newtonian counterparts
• I-Q relation for rapidly rotating neutron stars
• Tidal Love numbers of a slowly spinning neutron star
• Relativistic models for Superconducting-Superfluid Mixtures
• Effects of hyperons in binary neutron star mergers
• Quasi-Normal Modes of General Relativistic Superfluid Neutron Stars
• Breakdown of I-Love-Q universality in rapidly rotating relativistic stars
• On the universality of I-Love-Q relations in magnetized neutron stars
• A new temperature dependent hyperonic equation of state: application to rotating neutron star models and I-Q-relations
• Multipolar universal relations between f-mode frequency and tidal deformability of compact stars
• How loud are neutron star mergers?
• Multipole Love Relations
• Resonant tidal excitation of superfluid neutron stars in coalescing binaries
• Surrogate model for an aligned-spin effective one body waveform model of binary neutron star inspirals using Gaussian process regression
• Slowly Rotating General Relativistic Superfluid Neutron Stars
• Constraining nuclear matter parameters with GW170817
• Oscillations of General Relativistic Superfluid Neutron Stars
• Relativistic fluid dynamics: physics for many different scales
• Why I-Love-Q
• Frequency domain model of $f$-mode dynamic tides in gravitational waveforms from compact binary inspirals
• Rotating proto-neutron stars: spin evolution, maximum mass and I-Love-Q relations
• A Relativistic Mean Field Model for Entrainment in General Relativistic Superfluid Neutron Stars
• Oscillations of General Relativistic Multi-fluid/Multi-layer Compact Stars
• Relativistic numerical models for stationary superfluid Neutron Stars
• Universal relations for differentially rotating relativistic stars at the threshold to collapse
• Tidal deformations of neutron stars with elastic crusts
• Anti-glitches in the Ultraluminous Accreting Pulsar NGC 300 ULX-1 Observed with NICER
• Unveiling the universality of I-Love-Q relations
• Tidal deformation of a slowly rotating material body: Interior metric and Love numbers
• Tidal deformations of compact stars with crystalline quark matter
• Probing the interior of neutron stars with gravitational waves
• A superfluid perspective on neutron star dynamics
• Discovery of a Glitch in the Accretion Powered Pulsar SXP 1062
• Two-layer compact stars with crystalline quark matter: Screening effect on the tidal deformability
• Universal relations for the Keplerian sequence of rotating neutron stars
• Unified description of astrophysical properties of neutron stars independent of the equation of state
• Numerical models for stationary superfluid neutron stars in general relativity with realistic equations of state
• New quasi-universal relations for static and rapid rotating neutron stars
• Relativistic tidal properties of superfluid neutron stars
• Slowly Rotating General Relativistic Superfluid Neutron Stars with Relativistic Entrainment
• Universal relations for innermost stable circular orbits around rapidly rotating neutron stars
• Gravitational waveforms of binary neutron star inspirals using post-Newtonian tidal splicing
• Effect of superfluid matter of neutron star on the tidal deformability
• Isospin dependence of entrainment in superfluid neutron stars in a relativistic model

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• Tidal Deformability of Dark Matter Admixed Neutron Stars
• $I-$Love$-C$ relation for an anisotropic neutron star
• Rotating dark matter admixed neutron stars
• Rotating Love: The dynamical tides of spinning Newtonian stars
• Dynamical tides in superfluid neutron stars
• Universal relations for anisotropic interacting quark stars
• Fully general relativistic simulations of rapidly rotating quark stars: Oscillation modes and universal relations
• Universal Relations For Generic Family Of Neutron Star Equations Of State
• A revised formalism for slowly-rotating superfluid neutron stars in general relativity
• I-C-Q relations for rapidly rotating stable hybrid stars
• Equation-of-State Independent Relations in Rapidly Rotating Hybrid Stars
• Mass-radius relation, moment of inertia, and tidal love numbers of anisotropic neutron stars in f (R,T) gravity
• Rotation-dependent $I$-Love-$Q$-$\delta M$ relations in perturbation theory
• I-Love-Q Relations of Fermion-Boson Stars