2006/09/30 by Tomi Koivisto, David F. Mota
Physics and Astronomy · #Astrophysics #Baryon acoustic oscillations #Big Bang (financial markets) #Big Bang nucleosynthesis #Classical mechanics #Cold dark matter #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark energy #Dark matter #Einstein #Galaxies: Formation, Evolution, Phenomena #Gauss–Bonnet theorem #Lambda-CDM model #Matter power spectrum #Nucleosynthesis #Physics #Quantum mechanics #Quintessence #Scalar field #Scalar field dark matter #Supernova #Theoretical physics #astro-ph #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.75.023518
published as Phys.Rev.D75:023518,2007 · 20 pages, 21 figures. New figures and new matterial is included to the astrophysical constraint sections. Several disscussions were extended and improved. Abstract rewriten to comply with the new material in the text. Typos corrected. References added
arxiv created 2006/11/03 · openalex publication_date 2007/01/19 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We investigate a string-inspired dark energy scenario featuring a scalar field with a coupling to the Gauss-Bonnet invariant. We discuss extensively the cosmological and astrophysical implications of the coupled scalar field. Such coupling can trigger the onset of late dark energy domination after a scaling matter era. The universe may then cross the phantom divide and perhaps also exit from the acceleration. The evolution of fluctuations in the scalar field and their impact on the clustering of matter are studied in detail and model independently. The small-scale limit is derived for the perturbations and their stability is addressed. The general equations for scalar perturbations are also presented and solved numerically, confirming that the Gauss-Bonnet coupling can be compatible with the observed spectrum of cosmic microwave background radiation as well as the matter power spectrum inferred from large-scale surveys. Data from the solar system, supernovae Ia, cosmic microwave background radiation, large-scale structure, and big bang nucleosynthesis are used to constrain the parameters of the model. The geometric constraints from background expansion favor exponential potentials with a shallow slope, which is in tension with the nucleosynthesis bound on early quintessence. Also, high values for the present matter density are required. Including the baryon oscillation scale, one could rule out the model at about 99% confidence level. A discussion of how to overcome such possible problems in more elaborate models is included, together with considerations of the validity of these constraints in the present context. Interestingly, one also finds that a good Newtonian limit may require fixing the coupling.