Martinet, N, Schneider, P, Hildebrandt, H, Shan, H, Asgari, M, Dietrich, JP, Harnois-Déraps, J, Erben, T, Grado, A, Heymans, C, Hoekstra, H, Klaes, D, Kuijken, K, Merten, J and Nakajima, R (2018) KiDS-450: cosmological constraints from weak-lensing peak statistics – II: Inference from shear peaks using N-body simulations. Monthly Notices of the Royal Astronomical Society, 474 (1). pp. 712-730. ISSN 0035-8711

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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 S8=σ8Ωm/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.

Item Type:	Article
Additional Information:	This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords:	0201 Astronomical and Space Sciences
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press (OUP)
Date Deposited:	22 Jul 2020 10:41
Last Modified:	04 Sep 2021 06:57
DOI or ID number:	10.1093/mnras/stx2793
URI:	https://researchonline.ljmu.ac.uk/id/eprint/13345

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