Origin of weak lensing convergence peaks

Abstract

Weak lensing convergence peaks are a promising tool to probe nonlinear structure evolution at late times, providing additional cosmological information beyond second-order statistics. Previous theoretical and observational studies have shown that the cosmological constraints on Ωm and σ8 are improved by a factor of up to ≈ 2 when peak counts and second-order statistics are combined, compared to using the latter alone. We study the origin of lensing peaks using observational data from the 154 deg 2 Canada-France-Hawaii Telescope Lensing Survey. We found that while high peaks (with height κ > 3.5σκ, where σκ is the r.m.s. of the convergence κ) are typically due to one single massive halo of ≈ 10 15 M , low peaks (κ < ∼ σκ) are associated with constellations of 2-8 smaller halos ( < ∼ 10 13 M ). In addition, halos responsible for forming low peaks are found to be significantly offset from the line-of-sight towards the peak center (impact parameter > ∼ their virial radii), compared with ≈ 0.25 virial radii for halos linked with high peaks, hinting that low peaks are more immune to baryonic processes whose impact is confined to the inner regions of the dark matter halos. Our findings are in good agreement with results from the simulation work by Yang el al. 2011 [1].

Effects of baryons on weak lensing peak statistics

“…The origin of weak lensing peaks has been closely investigated in Refs. [34,35]. From there we know that the highest peaks are typically caused by one single massive halo.…”

The impact of baryonic physics and massive neutrinos on weak lensing peak statistics

“…Thus, the peak statistics contain information about the Universe on both non-linear and linear scales (e.g. Yang et al 2011;Liu & Haiman 2016;Martinet et al 2018).…”

“…A consideration of a broad range of cosmological models has been explored for S/N peak distributions (e.g. Yang et al 2011;Liu & Haiman 2016;Liu et al 2016;Martinet et al 2018;Peel et al 2018) but these simulations and other works do not include both the impact of summed neutrino mass and baryonic physics. In this paper we focus on baryonic physics and massive neutrinos and restrict our consideration to the two sets of cosmologies of BAHAMAS based on the WMAP 9-yr mission (WMAP 9, Hinshaw et al 2013) and the Planck 2015 mission (Planck 2015, Planck Collaboration et al 2016c parameters.…”

The self-similarity of weak lensing peaks

“…1 above highlights two important features in the behaviour of WL peaks: the number of WL peaks and their clustering, which are respectively quantified by two commonly used statistics, the peak abundance and the peak two point correlation function (2PCF). The former is well studied and has been considered for many cosmological applications (e.g., Liu et al 2015a;Liu & Haiman 2016;Liu et al 2016b;Shirasaki et al 2017;Shirasaki 2017;Shan et al 2018;Li et al 2018;Wei et al 2018), whereas weak lensing 2PCFs are usually measured as shear-shear correlations (Fu et al 2008;Heymans et al 2012;Kilbinger et al 2013), with very few studies directly focused on the peak 2PCFs (Marian et al 2013;Shan et al 2014).…”

“…WL peaks can also be extracted from CMB lensing to provide cosmological constraints (Liu et al 2016a). Various models have been developed to accurately describe high signal-to-noise-ratio (SNR) WL peaks (e.g., Hamana et al 2004;Hennawi & Spergel 2005;Maturi et al 2005;Fan et al 2010;Marian et al 2012;Hamana et al 2012;Liu & Haiman 2016;Shan et al 2018;Wei et al 2018).…”