Discrepancies between CFHTLenS cosmic shear and Planck: new physics or systematic effects?
File(s)
Published version
OA Location
Author(s)
Kitching, TD
Verde, L
Heavens, AF
Jimenez, R
Type
Journal Article
Abstract
There is currently a discrepancy in the measured value of the amplitude of matter clustering, parametrized using σ8, inferred from galaxy weak lensing, and cosmic microwave background (CMB) data, which could be an indication of new physics, such as massive neutrinos or a modification to the gravity law, or baryon feedback. In this paper we make the assumption that the cosmological parameters are well determined by Planck, and use weak lensing data to investigate the implications for baryon feedback and massive neutrinos, as well as possible contributions from intrinsic alignments and biases in photometric redshifts. We apply a non-parametric approach to model the baryonic feedback on the dark matter clustering, which is flexible enough to reproduce the OWLS (OverWhelmingly Large Simulations) and Illustris simulation results. The statistic we use, 3D cosmic shear, is a method that extracts cosmological information from weak lensing data using a spherical-Bessel function power spectrum approach. We analyse the CFHTLenS weak lensing data and, assuming best-fitting cosmological parameters from the Planck CMB experiment, find that there is no evidence for baryonic feedback on the dark matter power spectrum, but there is evidence for a bias in the photometric redshifts in the CFHTLenS data, consistent with a completely independent analysis by Choi et al., based on spectroscopic redshifts, and that these conclusions are robust to assumptions about the intrinsic alignment systematic. We also find an upper limit, of <0.28 eV (1σ), to the sum of neutrino masses conditional on other Λ-cold-dark-matter parameters being fixed.
Date Issued
2016-06-11
Date Acceptance
2016-03-21
Citation
Monthly Notices of the Royal Astronomical Society, 2016, 459 (1), pp.971-981
ISSN
1365-2966
Publisher
Oxford University Press (OUP)
Start Page
971
End Page
981
Journal / Book Title
Monthly Notices of the Royal Astronomical Society
Volume
459
Issue
1
Copyright Statement
© 2016 The Authors
Published by Oxford University Press on behalf of the Royal Astronomical Society
Published by Oxford University Press on behalf of the Royal Astronomical Society
Sponsor
Imperial College Trust
Imperial College Trust
Grant Number
N/A
NA
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
gravitational lensing: weak
cosmological parameters
MATTER POWER SPECTRUM
TELESCOPE LENSING SURVEY
DARK ENERGY
PHOTOMETRIC REDSHIFTS
PRECISION COSMOLOGY
GALAXY ALIGNMENTS
HALO MODEL
WEAK
CONSTRAINTS
TOMOGRAPHY
Publication Status
Published