KiDS-450: cosmological constraints from weak-lensing peak statistics - II: Inference from shear peaks using N-body simulations

Journal
Date Issued
2018
Author(s)
Martinet, Nicolas
•
Schneider, Peter
•
Hildebrandt, Hendrik
•
Shan, HuanYuan
•
Asgari, Marika
•
Dietrich, Jörg P.
•
Harnois-Déraps, Joachim
•
Erben, Thomas
•
•
Heymans, Catherine
•
Hoekstra, Henk
•
Klaes, Dominik
•
Kuijken, Konrad
•
•
Nakajima, Reiko
DOI
Abstract
We study the statistics of peaks in a weak-lensing reconstructed mass map of the first 450 deg2 of the Kilo Degree Survey (KiDS-450). The map is computed with aperture masses directly applied to the shear field with an NFW-like compensated filter. We compare the peak statistics in the observations with that of simulations for various cosmologies to constrain the cosmological parameter S_8 = σ _8 √{Ω _m/0.3}, which probes the (Ωm, σ8) plane perpendicularly to its main degeneracy. We estimate S8 = 0.750 ± 0.059, using peaks in the signal-to-noise range 0 ≤ S/N ≤ 4, and accounting for various systematics, such as multiplicative shear bias, mean redshift bias, baryon feedback, intrinsic alignment, and shear-position coupling. These constraints are ∼ 25 per cent tighter than the constraints from the high significance peaks alone (3 ≤ S/N ≤ 4) which typically trace single-massive haloes. This demonstrates the gain of information from low-S/N peaks. However, we find that including S/N < 0 peaks does not add further information. Our results are in good agreement with the tomographic shear two-point correlation function measurement in KiDS-450. Combining shear peaks with non-tomographic measurements of the shear two-point correlation functions yields a ∼20 per cent improvement in the uncertainty on S8 compared to the shear two-point correlation functions alone, highlighting the great potential of peaks as a cosmological probe.
Volume
474
Issue
1
Start page
712
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2018MNRAS.474..712M
Rights
open.access
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