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On the effects of coupled scalar fields on structure formation.

Li, B. and Barrow, J. D. (2011) 'On the effects of coupled scalar fields on structure formation.', Monthly notices of the Royal Astronomical Society., 413 (1). pp. 262-270.


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.

Item Type:Article
Keywords:Gravitation, Methods: numerical, Galaxies: haloes, Cosmology: theory, Dark energy, Large-scale structure of Universe.
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Publisher 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.
Date accepted:No date available
Date deposited:02 May 2014
Date of first online publication:May 2011
Date first made open access:No date available

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