Model independent inference of the expansion history and implications for the growth of structure
Abstract
We model the expansion history of the Universe as a Gaussian process and find constraints on the dark energy density and its lowredshift evolution using distances inferred from the Luminous Red Galaxy and Lymanalpha data sets of the Baryon Oscillation Spectroscopic Survey, supernova data from the Joint LightCurve Analysis sample, cosmic microwave background data from the Planck satellite, and local measurement of the Hubble parameter from the Hubble Space Telescope (H 0 ). Our analysis shows that the cosmic microwave background, Luminous Red Galaxy, Lymanalpha, and Joint LightCurve Analysis data are consistent with each other and with a Λ CDM cosmology, but the H 0 data are inconsistent at moderate significance. Including the presence of dark radiation does not alleviate the H 0 tension in our analysis. While some of these results have been noted previously, the strength here lies in that we do not assume a particular cosmological model. We calculate the growth of the gravitational potential in General Relativity corresponding to these general expansion histories and show that they are well approximated by Ω_{m}^{0.55} given the current precision. We assess the prospects for upcoming surveys to measure deviations from Λ CDM using this modelindependent approach.
 Publication:

Physical Review D
 Pub Date:
 June 2018
 DOI:
 10.1103/PhysRevD.97.123501
 arXiv:
 arXiv:1710.04236
 Bibcode:
 2018PhRvD..97l3501J
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 13 pages, 7 figures, code available at: https://github.com/dkirkby/gphist