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Dark energy constraints and correlations with systematics from CFHTLS weak lensing, SNLS supernovae Ia and WMAP5

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Date
2009
Lien vers un document non conservé dans cette base
http://arxiv.org/abs/0810.5129v2
Indexation documentaire
Sciences connexes (physique, astrophysique)
Subject
cosmology: observations; cosmology: cosmological parameters; methods: statistical
Nom de la revue
Astronomy & Astrophysics
Volume
497
Numéro
3
Date de publication
2009
Pages article
677-688
Nom de l'éditeur
EDP Sciences
DOI
http://dx.doi.org/10.1051/0004-6361/200811247
URI
https://basepub.dauphine.fr/handle/123456789/12637
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Auteur
Kilbinger, M.
Benabed, K.
Guy, J.
Astier, P.
Tereno, I.
Fu, L.
Wraith, Darren
Coupon, J.
Mellier, Y.
Balland, C.
Bouchet, F.R.
Hamana, T.
Hardin, D.
McCracken, H.J.
Pain, R.
Regnault, N.
Schultheis, M.
Yahagi, H.
Type
Article accepté pour publication ou publié
Résumé en anglais
Aims. We combine measurements of weak gravitational lensing from the CFHTLS-Wide survey, supernovae Ia from CFHT SNLS and CMB anisotropies from WMAP5 to obtain joint constraints on cosmological parameters, in particular, the dark-energy equation-of-state parameter w. We assess the influence of systematics in the data on the results and look for possible correlations with cosmological parameters. Methods. We implemented an MCMC algorithm to sample the parameter space of a flat CDM model with a dark-energy component of constant w. Systematics in the data are parametrised and included in the analysis. We determine the influence of photometric calibration of SNIa data on cosmological results by calculating the response of the distance modulus to photometric zero-point variations. The weak lensing data set is tested for anomalous field-to-field variations and a systematic shape measurement bias for high-redshift galaxies. Results. Ignoring photometric uncertainties for SNLS biases cosmological parameters by at most 20% of the statistical errors, using supernovae alone; the parameter uncertainties are underestimated by 10%. The weak-lensing field-to-field variance between 1 deg2-MegaCam pointings is 5-15% higher than predicted from N-body simulations. We find no bias in the lensing signal at high redshift, within the framework of a simple model, and marginalising over cosmological parameters. Assuming a systematic underestimation of the lensing signal, the normalisation $\sigma_8$ increases by up to 8%. Combining all three probes we obtain -0.10 < 1 + w < 0.06 at 68% confidence ( -0.18 < 1 + w < 0.12 at 95%), including systematic errors. Our results are therefore consistent with the cosmological constant $\Lambda$. Systematics in the data increase the error bars by up to 35%; the best-fit values change by less than 0.15$\sigma$.

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