Abstract
Abstract Using a perturbative approach we solve stellar structure equations for low-density (solar-type) stars whose interior is described with a polytropic equation of state in scenarios involving a subset of modified gravity (MG) theories. Rather than focusing on particular theories, we consider a model-independent approach in which deviations from General Relativity are effectively described by a single parameter ξ. We find that for length scales below those set by stellar General Relativistic radii the modifications introduced by MG can affect the computed values of masses and radii. As a consequence, the stellar luminosity is also affected. We discuss possible further implications for higher-density stars and observability of the effects previously described.
Highlights
It is well established that General Relativity (GR) provides an accurate description of the gravitational interaction from the submillimeter scales probed by torsion balance experiments (Adelberger et al 2003, 2009) to kiloparsec distances as confirmed by recent observations of strong gravitational lensing of extragalactic objects (Collett et al 2018)
Using a model-independent approach, we have studied the effects of a subset of modified gravity (MG) theories involving one extra scalar degree of freedom on stellar structure
We find that MG can affect stellar luminosity from its ξ dependence
Summary
It is well established that General Relativity (GR) provides an accurate description of the gravitational interaction from the submillimeter scales probed by torsion balance experiments (Adelberger et al 2003, 2009) to kiloparsec distances as confirmed by recent observations of strong gravitational lensing of extragalactic objects (Collett et al 2018). Effective descriptions of alternative gravity theories have been developed in recent years aiming to encapsulate in a few parameters all the relevant modifications at a given scale (Clifton et al 2012; Silvestri et al 2013) These parameterizations have been widely employed in the analysis of structure and lensing data of galaxy surveys (Amendola et al 2018). The μ(k) parameter changes the hydrostatic equilibrium equation introducing, generically, a new length scale in the dynamics and leading to expressions that can deviate from Equation (1) This effective approach will allow us to analyze the potential modifications in the stellar structure, including radius, mass, luminosity, and temperature of stars, in a largely model-independent way.
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