Constraining the time evolution of dark energy, curvature and neutrino properties with cosmic chronometers
Date Issued
2016
Author(s)
Moresco, Michele
•
Jimenez, Raul
•
Verde, Licia
•
CIMATTI, ANDREA
•
•
Maraston, Claudia
•
Thomas, Daniel
Abstract
We use the latest compilation of observational Hubble parameter measurements estimated with the differential evolution of cosmic chronometers, in the redshift range 00, a compilation of recent baryon acoustic oscillation data, and the latest type Ia cosmological supernovae sample. From late-Universe probes alone (z<2) we find that w0 = -0.9 ± 0.18 and wa = -0.5 ± 1.7, and when combining also Planck 2015 data we obtain w0=-0.98± 0.11 and wa=-0.30±0.4. These new constraints imply that nearly all quintessence models are disfavoured by the data; only phantom models or a pure cosmological constant are favoured. This is a remarkable finding as it imposes severe constraints on the nature of dark energy. For the curvature our constraints are Ωk = 0.003 ± 0.003, considering also CMB data. We also find that H(z) data from cosmic chronometers are important to constrain parameters that do no affect directly the expansion history, by breaking or reducing degeneracies with other parameters. We find that Neff = 3.17 ± 0.15, thus excluding the possibility of an extra (sterile) neutrino at more than 5 σ, and put competitive limits on the sum of neutrino masses, Σ mν< 0.27 eV at 95% confidence level. Finally, we constrain the redshift evolution of dark energy by exploring separately the early and late-Universe, and find a dark energy equation of state evolution w(z) consistent with that in the ΛCDM model at the ± 0.4 level over the entire redshift range 0 < z < 2.
Volume
2016
Issue
12
Start page
039
Issn Identifier
1475-7516
Ads BibCode
2016JCAP...12..039M
Rights
open.access
File(s)![Thumbnail Image]()
![Thumbnail Image]()
Loading...
Name
Moresco_1604.00183.pdf
Description
preprint
Size
2.48 MB
Format
Adobe PDF
Checksum (MD5)
e76841a9af35efdc2a0ceb6bc7109731
Loading...
Name
Moresco_2016_J._Cosmol._Astropart._Phys._2016_039.pdf
Description
pdf editoriale
Size
2.77 MB
Format
Adobe PDF
Checksum (MD5)
de6acc3f695edae2f56ff917f6e51765