Spherically symmetric isothermal fluids in $f(R,T)$ gravity

Abstract

We analyze the isothermal property in static fluid spheres within the framework of the modified $f(R,T)$ theory of gravitation. The equation of pressure isotropy of the standard Einstein theory is preserved however, the energy density and pressure are expressed in terms of both gravitational potentials. Invoking the isothermal prescription requires that the isotropy condition assumes the role of a consistency condition and an exact model generalizing that of general relativity is found. Moreover it is found that the Einstein model is unstable and acausal while the $f(R,T)$ counterpart is well behaved on account of the freedom available through an additional coupling constant. The case of a constant spatial gravitational potential is considered and the complete model is determined. This model is markedly different from its Einstein counterpart which is known to be isothermal. Dropping the restriction on the density and imposing a linear barotropic equation of state generates an exact solution and consequently a stellar distribution as the vanishing of the pressure is possible and a boundary hypersurface exists. Finally we comment on the case of relaxing the equation of state but demanding an inverse square fall-off of the density - this case proves intractable.

References in corpus (25)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• f(R) theories
• f(R,T) gravity
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Angular Power Spectrum
• Physical Acceptability of Isolated, Static, Spherically Symmetric, Perfect Fluid Solutions of Einstein's Equations
• General second order scalar-tensor theory, self tuning, and the Fab Four
• Reconstruction of some cosmological models in f(R,T) gravity
• Thermodynamics in f(R,T) Theory of Gravity
• Cosmological and Solar System Consequences of f(R,T) Gravity Models
• FRW Cosmology in F(R,T) gravity
• General Relativity and Cosmology: Unsolved Questions and Future Directions
• The Influence of Modification of Gravity on the Dynamics of Radiating Spherical Fluids
• Black Hole Solutions in Rastall Theory
• A complete cosmological scenario from $f(R,T^{\phi })$ gravity theory
• Existence of Compact Structures in $f(R,T)$ Gravity
• Exact barotropic distributions in Einstein-Gauss-Bonnet gravity
• Cosmological Evolution in f(R,T) theory with Collisional Matter
• Twenty Five Years of Asymptotic Freedom
• Configurational entropy in $f(R,T)$ brane models
• Buchdahl-Bondi limit in modified gravity: Packing extra effective mass in relativistic compact stars
• Compact objects in Horndeski gravity
• Universality of isothermal fluid spheres in Lovelock gravity
• Compact objects in pure Lovelock theory

Cited by in corpus (2)

• Gravitationally decoupled strange star model beyond standard maximum mass limit in Einstein-Gauss-Bonnet gravity
• Charged quark stars in $f(R,T)$ gravity