Stability of neutron stars in Horndeski theories with Gauss-Bonnet couplings

Abstract

In Horndeski theories containing a scalar coupling with the Gauss-Bonnet (GB) curvature invariant $R_{\mathrm{GB}}^2$, we study the existence and linear stability of neutron star (NS) solutions on a static and spherically symmetric background. For a scalar-GB coupling of the form $\alpha \xi (\varphi )R_{\mathrm{GB}}^2$, where $\xi$ is a function of the scalar field $\varphi$, the existence of linearly stable stars with a nontrivial scalar profile without instabilities puts an upper bound on the strength of the dimensionless coupling constant $|\alpha |$. To realize maximum masses of NSs for a linear (or dilatonic) GB coupling ${\alpha }_{\mathrm{GB}}\varphi R_{\mathrm{GB}}^2$ with typical nuclear equations of state, we obtain the theoretical upper limit $\sqrt{|{\alpha }_{\mathrm{GB}}|}<0.7\mathrm{km}$. This is tighter than those obtained by the observations of gravitational waves emitted from binaries containing NSs. We also incorporate cubic-order scalar derivative interactions, quartic derivative couplings with nonminimal couplings to a Ricci scalar besides the scalar-GB coupling and show that NS solutions with a nontrivial scalar profile satisfying all the linear stability conditions are present for certain ranges of the coupling constants. In regularized 4-dimensional Einstein-GB gravity obtained from a Kaluza-Klein reduction with an appropriate rescaling of the GB coupling constant, we find that NSs in this theory suffer from a strong coupling problem as well as Laplacian instability of even-parity perturbations. We also study NS solutions with a nontrivial scalar profile in power-law $F(R_{\mathrm{GB}}^2)$ models, and show that they are pathological in the interior of stars and plagued by ghost instability together with the asymptotic strong coupling problem in the exterior of stars.

27 pages, 5 figures

References in corpus (37)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Dynamics of dark energy
• Beyond the Cosmological Standard Model
• Approaches to Understanding Cosmic Acceleration
• Construction of cosmologically viable f(G) gravity models
• The Cosmology of Modified Gauss-Bonnet Gravity
• Rotating Black Holes in Dilatonic Einstein-Gauss-Bonnet Theory
• Are black holes in alternative theories serious astrophysical candidates? The case for Einstein-Dilaton-Gauss-Bonnet black holes
• Horndeski Gravity as $D\to 4$ Limit of Gauss-Bonnet
• On Taking the $D\to 4$ limit of Gauss-Bonnet Gravity: Theory and Solutions
• Derivation of Regularized Field Equations for the Einstein-Gauss-Bonnet Theory in Four Dimensions
• Slowly-Rotating Black Holes in Einstein-Dilaton-Gauss-Bonnet Gravity: Quadratic Order in Spin Solutions
• Analytical representations of unified equations of state of neutron-star matter
• Constraints on scalar-tensor models of dark energy from observational and local gravity tests
• Self-interactions and Spontaneous Black Hole Scalarization
• Effective scalar-tensor description of regularized Lovelock gravity in four dimensions
• Structure of neutron stars in R-squared gravity
• Stability of Schwarzschild-like solutions in f(R,G) gravity models
• Black Holes in the Dilatonic Einstein-Gauss-Bonnet Theory in Various Dimensions I -- Asymptotically Flat Black Holes --
• Quadrupole Moments of Rapidly Rotating Compact Objects in Dilatonic Einstein-Gauss-Bonnet Theory
• Constraints on Einstein-dilaton-Gauss-Bonnet gravity from Black Hole-Neutron Star Gravitational Wave Events
• Towards Strong Field Tests of Beyond Horndeski Gravity Theories
• Relativistic stars in 4D Einstein-Gauss-Bonnet gravity
• Extremal black holes in D=4 Gauss-Bonnet gravity
• Tidal Deformabilities of Neutron Stars in scalar-Gauss-Bonnet Gravity and Their Applications to Multimessenger Tests of Gravity
• Black Holes in the Scalar-Tensor Formulation of 4D Einstein-Gauss-Bonnet Gravity: Uniqueness of Solutions, and a New Candidate for Dark Matter
• A no-hair theorem for stars in Horndeski theories
• Jordan frame no-hair for spherical scalar-tensor black holes
• Unsuccessful cosmology with Modified Gravity Models
• Hairy Black-holes in Shift-symmetric Theories
• Relativistic star perturbations in Horndeski theories with a gauge-ready formulation
• Linear stability of black holes in shift-symmetric Horndeski theories with a time-independent scalar field
• Linear stability of black holes with static scalar hair in full Horndeski theories: generic instabilities and surviving models
• Stability of relativistic stars with scalar hairs
• Relativistic stars in a cubic Galileon Universe
• Instability of compact stars with a nonminimal scalar-derivative coupling
• Instability of hairy black holes in regularized 4-dimensional Einstein-Gauss-Bonnet gravity

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