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On the effects of coupled scalar fields on structure formation

Li, B.; Barrow, J.D.

On the effects of coupled scalar fields on structure formation Thumbnail


J.D. Barrow


A coupling between a scalar field (representing the dark energy) and dark matter could produce rich phenomena in cosmology. It affects cosmic structure formation mainly through the fifth force, a velocity-dependent force that acts parallel to particle’s direction of motion and proportional to its speed, an effective rescaling of the particle masses and a modified background expansion rate. In many cases, these effects entangle and it is difficult to see which is the dominant one. Here, we perform N-body simulations to study their qualitative behaviour and relative importance in affecting the key structure formation observables, for a model with exponential scalar field coupling. We find that the fifth force, a prominent example of the scalar-coupling effects, is far less important than the rescaling of particle mass or the modified expansion rate in its effects on the matter power spectrum and mass function. In particular, the rescaling of particle masses is shown to be the key factor leading to less concentration of particles in haloes than in Λcold dark matter, a pattern which is also observed in previous independent coupled scalar field simulations.

Journal Article Type Article
Publication Date May 1, 2011
Deposit Date Jan 20, 2012
Publicly Available Date May 2, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 413
Issue 1
Pages 262-270
Keywords Gravitation, Methods: numerical, Galaxies: haloes, Cosmology: theory, Dark energy, Large-scale structure of Universe.
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Published Journal Article (1 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS Published by Oxford University Press on behalf of The Royal Astronomical Society. All rights reserved.

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