Dynamical and gravitational instability of an oscillating-field dark energy and dark matter

Journal Article · Mon Sep 15 04:00:00 EDT 2008 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.78.063010· OSTI ID:21250804

Johnson, Matthew C; Kamionkowski, Marc ^[1]

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1. California Institute of Technology, Mail Code 130-33, Pasadena, California 91125 (United States)

Coherent oscillations of a scalar field can mimic the behavior of a perfect fluid with an equation-of-state parameter determined by the properties of the potential, possibly driving accelerated expansion in the early Universe (inflation) and/or in the Universe today (dark energy) or behaving as dark matter. We consider the growth of inhomogeneities in such a field, mapping the problem to that of two coupled anharmonic oscillators. We provide a simple physical argument that oscillating fields with a negative equation-of-state parameter possess a large-scale dynamical instability to growth of inhomogeneities. This instability renders these models unsuitable for explaining cosmic acceleration. We then consider the gravitational instability of oscillating fields in potentials that are close to, but not precisely, harmonic. We use these results to show that if axions make up the dark matter, then the small-scale cutoff in the matter power spectrum is around 10{sup -15}M{sub +}.

• OSTI ID: 21250804
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 6 Vol. 78; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCELERATION
ANHARMONIC OSCILLATORS
AXIONS
EQUATIONS OF STATE
FIELD THEORIES
GRAVITATIONAL INSTABILITY
IDEAL FLOW
INFLATION
NONLUMINOUS MATTER
OSCILLATIONS
POTENTIALS
SCALAR FIELDS
SPECTRA
UNIVERSE