The virial theorem and the dark matter problem in hybrid metric-Palatini gravity
- Dipartimento di Scienze Fisiche, Università di Napoli ''Federico II'', Napoli (Italy)
- Department of Mathematics, University College London, Gower Street, London WC1E 6BT (United Kingdom)
- Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway)
- Centro de Astronomia e Astrofísica da Universidade de Lisboa, Campo Grande, Ed. C8 1749-016 Lisboa (Portugal)
Hybrid metric-Palatini gravity is a recently proposed theory, consisting of the superposition of the metric Einstein-Hilbert Lagrangian with an f(R) term constructed à la Palatini. The theory predicts the existence of a long-range scalar field, which passes the Solar System observational constraints, even if the scalar field is very light, and modifies the cosmological and galactic dynamics. Thus, the theory opens new possibilities to approach, in the same theoretical framework, the problems of both dark energy and dark matter. In this work, we consider the generalized virial theorem in the scalar-tensor representation of the hybrid metric-Palatini gravity. More specifically, taking into account the relativistic collisionless Boltzmann equation, we show that the supplementary geometric terms in the gravitational field equations provide an effective contribution to the gravitational potential energy. We show that the total virial mass is proportional to the effective mass associated with the new terms generated by the effective scalar field, and the baryonic mass. In addition to this, we also consider astrophysical applications of the model and show that the model predicts that the mass associated to the scalar field and its effects extend beyond the virial radius of the clusters of galaxies. In the context of the galaxy cluster velocity dispersion profiles predicted by the hybrid metric-Palatini model, the generalized virial theorem can be an efficient tool in observationally testing the viability of this class of generalized gravity models.
- OSTI ID:
- 22282803
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2013, Issue 07; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ASTROPHYSICS
BARYONS
BOLTZMANN-VLASOV EQUATION
EFFECTIVE MASS
GALAXY CLUSTERS
GEOMETRY
GRAVITATIONAL FIELDS
LAGRANGIAN FUNCTION
LIMITING VALUES
METRICS
NONLUMINOUS MATTER
POTENTIAL ENERGY
RELATIVISTIC RANGE
SCALAR FIELDS
SOLAR SYSTEM
TENSORS
VIRIAL THEOREM
VISIBLE RADIATION