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Title: Galileons and strong gravity

In the context of a cubic Galileon model in which the Vainshtein mechanism suppresses the scalar field interactions with matter, we study low-density stars with slow rotation and static relativistic stars. We develop an expansion scheme to find approximated solutions inside the Vainshtein radius, and show that deviations from General Relativity (GR), while considering rotation, are also suppressed by the Vainshtein mechanism. In a quadratic coupling model, in which the scalarisation effect can significantly enhance deviations from GR in normal scalar tensor gravity, the Galileon term successfully suppresses the large deviations away from GR. Moreover, using a realistic equation of state, we construct solutions for a relativistic star, and show that deviations from GR are more suppressed for higher density objects. However, we found that the scalar field solution ceases to exist above a critical density, which roughly corresponds to the maximum mass of a neutron star. This indicates that, for a compact object described by a polytropic equation of state, the configuration that would collapse into a black hole cannot support a non-trivial scalar field.
Authors:
 [1] ; ; ;  [2]
  1. Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX (United Kingdom)
  2. Departamento de Física, Universidad de Guanajuato, DCI, Campus León, C.P. 37150, León, Guanajuato (Mexico)
Publication Date:
OSTI Identifier:
22375772
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 10; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; BLACK HOLES; DENSITY; EQUATIONS OF STATE; GENERAL RELATIVITY THEORY; GRAVITATION; MASS; MATHEMATICAL SOLUTIONS; MATTER; NEUTRON STARS; RELATIVISTIC RANGE; ROTATION; SCALAR FIELDS; SCALARS; TENSORS