Strong-field effects in massive scalar-tensor gravity for slowly spinning neutron stars and application to X-ray pulsar pulse profiles

Abstract

Neutron stars (NSs) in scalar-tensor (ST) theories of gravitation can acquire scalar charges and generate distinct spacetimes from those in General Relativity (GR) through the celebrated phenomenon of spontaneous scalarization. Taking on an ST theory with the mass term of the scalar field, we determine the theory parameter space for spontaneous scalarization by investigating the linearized scalar field equation. Then the full numerical solutions for slowly rotating NSs are obtained and studied in great detail. The resulted spacetime is used to calculate test-particle geodesics. The lightlike geodesics are used to construct the profile of X-ray radiation from a pair of hot spots on the surface of scalarized NSs, which potentially can be compared with the data from the Neutron star Interior Composition Explorer (NICER) mission for testing the ST theory.

15 pages, 10 figures; accepted by PRD

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• Static Neutron Stars Perspective of Quadratic and Induced Inflationary Attractor Scalar-tensor Theories
• Neutron stars in massive scalar-Gauss-Bonnet gravity: Spherical structure and time-independent perturbations
• Quasi-universality of the magnetic deformation of neutron stars in general relativity and beyond
• Uniqueness of the Inflationary Higgs Scalar for Neutron Stars and Failure of non-inflationary Approximations
• Compact Objects in Entangled Relativity
• Stringent Tests of Gravity with Highly Relativistic Binary Pulsars in the Era of LISA and SKA
• Effects from Dark Matter Halos on X-ray Pulsar Pulse Profiles
• Scalar-tensor gravity from thermodynamic and fluid-gravity perspective
• Neutron stars as extreme gravity probes