KiDS+VIKING-450 cosmology with Bayesian hierarchical model redshift distributions
Abstract
Tomographic redshift distributions from photometric data are crucial ingredients in cosmic shear analysis, since they are required for the theoretical calculation of the signal based on the redshift distribution of the galaxies where the shear field is sampled. In this paper, we develop as a proof of concept Leistedt et al.'s template-based Bayesian Hierarchical Model framework into an application to weak lensing data by sampling the redshift distributions of the galaxies in the KiDS+VIKING-450 survey. We also use a principal component analysis to provide a set of representative templates drawn from a large superset. For computational tractability, subsets of $10^5$ galaxies are chosen to determine the redshift distributions, and we test the sensitivity of the cosmological inference to the subset chosen, finding it to be subdominant compared to the statistical error. We marginalise over the inferred redshift distributions and find that the Bayesian method increases the clustering parameter compared with previous studies, alleviating the $S_8$ tension with Planck, where $S_{8}\equivσ_{8}\sqrt{Ω_{\tm{m}}/0.3}=0.756\pm 0.039$, assuming flat $Λ$CDM. The tension with Planck for this survey is reduced from $2.3σ$ to $1.9σ$. We also infer a value for the matter density, $Ω_{\tm{m}}=0.31\pm 0.10$.
Authors 6
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Affiliation as printed
Imperial Centre for Inference and Cosmology (ICIC) , Imperial Astrophysics , Imperial College , Blackett Laboratory , Prince Consort Road , London , SW7 2AZ , UK
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University of Oxford · Imperial College London
Affiliation as printed
Imperial Centre for Inference and Cosmology (ICIC) , Imperial Astrophysics , Imperial College , Blackett Laboratory , Prince Consort Road , London , SW7 2AZ , UK
Oxford Astrophysics , Department of Physics , University of Oxford , Denys Wilkinson Building , Keble Road , Oxford , OX1 3RH , UK
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Institut d'Astrophysique de Paris · Sorbonne Université · Imperial College London
Affiliation as printed
Imperial Centre for Inference and Cosmology (ICIC) , Imperial Astrophysics , Imperial College , Blackett Laboratory , Prince Consort Road , London , SW7 2AZ , UK
Sorbonne Université , UMR 7095 , Institut d'Astrophysique de Paris , 98 bis boulevard Arago , F-75014 Paris , France
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Affiliation as printed
Imperial Centre for Inference and Cosmology (ICIC) , Imperial Astrophysics , Imperial College , Blackett Laboratory , Prince Consort Road , London , SW7 2AZ , UK
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Centre National de la Recherche Scientifique
Affiliation as printed
CNRS &
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory , Leiden University , P.O. Box 9513 , 2300 RA Leiden , The Netherlands