2016/08/10 by Hui–Yiing Chang, Robert J. Scherrer, Chang, Hui-Yiing +1
Physics and Astronomy · #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Noncommutative and Quantum Gravity Theories #Particle physics theoretical and experimental studies
paper · pdf · doi:10.48550/arxiv.1608.03291
openalex publication_date 2016/08/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We examine a quintessence model with a modified exponential potential given by V(ϕ) = V0(1+e-λϕ). Unlike quintessence with a standard exponential potential, our model can yield an acceptable accelerated expansion at late times, while producing a distinct "early dark energy" signature at high redshift. We determine the evolution of the equation of state parameter, wϕ, and the density parameter, Ωϕ, as a function of the scale factor. The strongest constraints on the model come from cosmic microwave background observations rather than supernova data. The former give the limit λ> 13. This model predicts a value of the effective neutrino number during Big Bang nucleosynthesis larger than the standard model value. It also provides a partial solution to the coincidence problem, in that the ratio of the quintessence energy density is always within a few orders of magnitude of the background radiation or matter density from the early universe up to the present, but it does not explain why the accelerated expansion is beginning near the present day, suggesting that these two different ways of characterizing the coincidence problem are not entirely equivalent.