Cosmological attractors to general relativity and spontaneous scalarization with disformal coupling

Abstract

The canonical scalar-tensor theory model which exhibits spontaneous scalarization in the strong-gravity regime of neutron stars has long been known to predict a cosmological evolution for the scalar field which generically results in severe violations of present-day Solar System constraints on deviations from general relativity. We study if this tension can be alleviated by generalizing this model to include a disformal coupling between the scalar field $\phi$ and matter, where the Jordan frame metric ${\tilde{g}}_{\mu \nu }$ is related to the Einstein frame one $g_{\mu \nu }$ by ${\tilde{g}}_{\mu \nu }=A(\phi {)}^2(g_{\mu \nu }+\Lambda {\partial }_{\mu }\phi {\partial }_{\nu }\phi )$. We find that this broader theory admits a late-time attractor mechanism towards general relativity. However, the existence of this attractor requires a value of disformal scale of the order $\Lambda \gtrsim H_0^{-2}$, where $H_0$ is the Hubble parameter of today, which is much larger than the scale relevant for spontaneous scalarization of neutron stars $\Lambda \sim R_s^2$ with $R_s(\sim 10^{-22}{H}_0^{-1})$ being the typical radius of these stars. The large values of $\Lambda$ necessary for the attractor mechanism (i) suppress spontaneous scalarization altogether inside neutron stars and (ii) induce ghost instabilities on scalar field fluctuations, thus preventing a resolution of the tension. We argue that the problem arises because our disformal coupling involves a dimensionful parameter.

arXiv comment(v1) 10 pages, 2 figures. (v2) typos corrected. (v3) 11 pages, new references, matches published version

References in corpus (49)

• The Confrontation between General Relativity and Experiment
• Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
• Testing General Relativity with Present and Future Astrophysical Observations
• Covariant Galileon
• Dark Energy after GW170817: dead ends and the road ahead
• Strong constraints on cosmological gravity from GW170817 and GRB 170817A
• Dark Energy after GW170817 and GRB170817A
• Implications of the Neutron Star Merger GW170817 for Cosmological Scalar-Tensor Theories
• Varying constants, Gravitation and Cosmology
• Spontaneous scalarization of black holes and compact stars from a Gauss-Bonnet coupling
• Tensor-scalar gravity and binary-pulsar experiments
• Degenerate higher derivative theories beyond Horndeski: evading the Ostrogradski instability
• Horndeski theory and beyond: a review
• New Gauss-Bonnet black holes with curvature induced scalarization in the extended scalar-tensor theories
• Transforming gravity: from derivative couplings to matter to second-order scalar-tensor theories beyond the Horndeski Lagrangian
• The relativistic pulsar-white dwarf binary PSR J1738+0333 II. The most stringent test of scalar-tensor gravity
• Evasion of No-Hair Theorems and Novel Black-Hole Solutions in Gauss-Bonnet Theories
• The Relation between Physical and Gravitational Geometry
• Degenerate higher order scalar-tensor theories beyond Horndeski up to cubic order
• Extreme Gravity Tests with Gravitational Waves from Compact Binary Coalescences: (II) Ringdown
• Degenerate higher order scalar-tensor theories beyond Horndeski and disformal transformations
• New varying speed of light theories
• Scalar-tensor theories and modified gravity in the wake of GW170817
• Disformal invariance of second order tensor-scalar theories: framing the Horndeski action
• Extreme Gravity Tests with Gravitational Waves from Compact Binary Coalescences: (I) Inspiral-Merger
• Testing the universality of free fall by tracking a pulsar in a stellar triple system
• Resilience of the standard predictions for primordial tensor modes
• Neutron stars in scalar-tensor theories of gravity and catastrophe theory
• Vainshtein mechanism after GW170817
• Constraining nonperturbative strong-field effects in scalar-tensor gravity by combining pulsar timing and laser-interferometer gravitational-wave detectors
• Stability Analysis of Spherically Symmetric Star in Scalar-Tensor Theories of Gravity
• Disformal Inflation
• Neutron star transition to strong-scalar-field state in tensor scalar gravity
• Disformal Theories of Gravity: From the Solar System to Cosmology
• Spontaneous scalarization in generalised scalar-tensor theory
• Relativistic stars in scalar-tensor theories with disformal coupling
• Cosmological disformal invariance
• Disformal Gravity Theories: A Jordan Frame Analysis
• Disformal transformation of cosmological perturbations
• Towards Viable Cosmological Models of Disformal Theories of Gravity
• The Effect of Cosmological Evolution on Solar System Constraints and on the Scalarization of Neutron Stars in Massless Scalar-Tensor Theories
• Disformal invariance of cosmological perturbations in a generalized class of Horndeski theories
• Solar System Constraints on Disformal Gravity Theories
• Disformal invariance of curvature perturbation
• Spontaneous scalarization of black holes in the Horndeski theory
• Cosmological instability of scalar-Gauss-Bonnet theories exhibiting scalarization
• Multi-disformal invariance of nonlinear primordial perturbations
• Cosmological Evolution and Solar System Consistency of Massive Scalar-Tensor Gravity
• Disformally coupled inflation

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