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Exploring uncertainties in dark energy constraints using current observational data with Planck 2015 distance priors

Wang, Yun and Dai, Mi (2016) Exploring uncertainties in dark energy constraints using current observational data with Planck 2015 distance priors. Physical Review D, 94 (8). Art. No. 083521. ISSN 1550-7998 . http://resolver.caltech.edu/CaltechAUTHORS:20160718-151753061

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Abstract

We present the distance priors that we have derived from the 2015 Planck data, and use these in combination with the latest observational data from Type Ia supernovae (SNe Ia) and galaxy clustering, to explore the systematic uncertainties in dark energy constraints. We use the joint light-curve analysis (JLA) set of 740 SNe Ia, galaxy clustering measurements of H(z)s and DA(z)/s (where s is the sound horizon at the drag epoch) from the Sloan Digital Sky Survey (SDSS) at z = 0.32 and z = 0.57 (BOSS DR12). We find that the combined dark energy constraints are insensitive to the assumptions made in the galaxy clustering measurements (whether they are for BAO only or marginalized over RSD), which indicates that as the analysis of galaxy clustering data becomes more accurate and robust, the systematic uncertainties are reduced. On the other hand, we find that flux-averaging SNe Ia at z ≥ 0.5 significantly tightens the dark energy constraints and excludes a flat universe with a cosmological constant at 68% confidence level, assuming a dark energy equation of state linear in the cosmic scale factor. Flux averaging has the most significant effect when we allow the dark energy density function X(z) to be a free function given by the cubic spline of its values at z = 0, 1/3, 2/3, 1; the measured X(z) deviates from a cosmological constant at more than 95% confidence level for 0.4 ≲ z ≲ 0.7. Since flux averaging reduces the bias in the SN distance measurements, this may be an indication that we have arrived in the era when the SN distance measurements are limited by systematic uncertainties.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1103/PhysRevD.94.083521DOIArticle
http://journals.aps.org/prd/abstract/10.1103/PhysRevD.94.083521PublisherArticle
http://arxiv.org/abs/1509.02198arXivDiscussion Paper
Additional Information:© 2016 American Physical Society. (Received 9 September 2015; published 21 October 2016) We are grateful to Rick Kessler and Ranga Chary for helpful discussions, and to Alex Merson for providing python scripts for making 2D contour plots. We acknowledge the use of the Planck data arXiv and CosmoMC.
Group:Infrared Processing and Analysis Center (IPAC)
Subject Keywords:Cosmology
Classification Code:PACS: 98.80.Es,98.80.-k,98.80.Jk
Record Number:CaltechAUTHORS:20160718-151753061
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160718-151753061
Official Citation:Exploring uncertainties in dark energy constraints using current observational data with Planck 2015 distance priors Yun Wang and Mi Dai Phys. Rev. D 94, 083521
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69098
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:26 Jul 2016 23:53
Last Modified:21 Oct 2016 16:59

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