Structure of neutron stars in R-squared gravity

Abstract

The effects implied for the structure of compact objects by the modification of General Relativity produced by the generalization of the Lagrangian density to the form f(R)=R+αR^2, where R is the Ricci curvature scalar, have been recently explored. It seems likely that this squared-gravity may allow heavier Neutron Stars (NSs) than GR. In addition, these objects can be useful to constrain free parameters of modified-gravity theories. The differences between alternative gravity theories is enhanced in the strong gravitational regime. In this regime, because of the complexity of the field equations, perturbative methods become a good choice to treat the problem. Following previous works in the field, we performed a numerical integration of the structure equations that describe NSs in f(R)-gravity, recovering their mass-radius relations, but focusing on particular features that arise from this approach in the profiles of the NS interior. We show that these profiles run in correlation with the second-order derivative of the analytic approximation to the Equation of State (EoS), which leads to regions where the enclosed mass decreases with the radius in a counter-intuitive way. We reproduce all computations with a simple polytropic EoS to separate zeroth-order modified gravity effects.

9 pages, 12 figures, accepted for publication in General Relativity and Gravitation

References in corpus (8)

• Shapiro delay measurement of a two solar mass neutron star
• Models of f(R) Cosmic Acceleration that Evade Solar-System Tests
• Spectra and Light Curves of Six Type Ia Supernovae at 0.511 < z < 1.12 and the Union2 Compilation
• Disappearing cosmological constant in f(R) gravity
• Constraints on a phenomenologically parameterized neutron-star equation of state
• Structure of neutron stars in R-squared gravity
• Robust approach to f(R) gravity
• Gravity with Perturbative Constraints: Dark Energy Without New Degrees of Freedom

Cited by in corpus (9)

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• Structure of neutron stars in R-squared gravity
• Rapidly rotating neutron stars in $R$-squared gravity
• Spherically symmetric black holes with electric and magnetic charge in extended gravity: Physical properties, causal structure, and stability analysis in Einstein's and Jordan's frames
• Modified Einstein's gravity as a possible missing link between sub- and super-Chandrasekhar type Ia supernovae
• Neutron stars in Scalar-Tensor-Vector Gravity
• Structure of Compact Stars in R-squared Palatini Gravity
• Self-gravitating systems in Extended Gravity
• Role of $\sigma R^2+\gamma R_{\mu \nu }{T}^{\mu \nu }$ Model on Anisotropic Polytropes