Galileons and strong gravity

Journal Article · Wed Oct 01 04:00:00 EDT 2014 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2014/10/055· OSTI ID:22375772

Chagoya, Javier ^[1]; Koyama, Kazuya; Niz, Gustavo; Tasinato, Gianmassimo ^[2]

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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)

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.

• OSTI ID: 22375772
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 10 Vol. 2014; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
APPROXIMATIONS
BLACK HOLES
DENSITY
EQUATIONS OF STATE
GENERAL RELATIVITY THEORY
GRAVITATION
MASS
MATHEMATICAL SOLUTIONS
MATTER
NEUTRON STARS
RELATIVISTIC RANGE
ROTATION
SCALAR FIELDS
SCALARS
TENSORS