Implications of a transition in the dark energy equation of state for the H_{0} and σ_{8} tensions
Abstract
We explore the implications of a rapid appearance of dark energy between the redshifts (z) of one and two on the expansion rate and growth of perturbations. Using both Gaussian process regression and a parametric model, we show that this is the preferred solution to the current set of lowredshift (z<3) distance measurements if H_{0}=73 km s^{1} Mpc^{1} to within 1% and the highredshift expansion history is unchanged from the ΛCDM inference by the Planck satellite. Dark energy was effectively nonexistent around z=2, but its density is close to the ΛCDM model value today, with an equation of state greater than 1 at z<0.5. If sources of clustering other than matter are negligible, we show that this expansion history leads to slower growth of perturbations at z<1, compared to ΛCDM, that is measurable by upcoming surveys and can alleviate the σ_{8} tension between the Planck CMB temperature and lowredshift probes of the largescale structure.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 December 2019
 DOI:
 10.1088/14757516/2019/12/035
 arXiv:
 arXiv:1905.10198
 Bibcode:
 2019JCAP...12..035K
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 24 pages, 16 figures