ON THE ACCURACY OF WEAK-LENSING CLUSTER MASS RECONSTRUCTIONS

By Matthew R. Becker, Andrey V. Kravtsov. 2010

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We study the bias and scatter in mass measurements of galaxy clusters resulting from fitting a spherically symmetric Navarro, Frenk, & White model to the reduced tangential shear profile measured in weak-lensing (WL) observations. The reduced shear profiles are generated for ≈104 cluster-sized halos formed in a ΛCDM cosmological N-body simulation of a 1 h−1 Gpc box. In agreement with previous studies, we find that the scatter in the WL masses derived using this fitting method has irreducible contributions from the triaxial shapes of cluster-sized halos and uncorrelated large-scale matter projections along the line of sight. Additionally, we find that correlated large-scale structure within several virial radii of clusters contributes a smaller, but nevertheless significant, amount to the scatter. The intrinsic scatter due to these physical sources is ≈20% for massive clusters and can be as high as ≈30% for group-sized systems. For current, ground-based observations, however, the total scatter should be dominated by shape noise from the background galaxies used to measure the shear. Importantly, we find that WL mass measurements can have a small, ≈5%–10%, but non-negligible amount of bias. Given that WL measurements of cluster masses are a powerful way to calibrate cluster mass–observable relations for precision cosmological constraints, we strongly emphasize that a robust calibration of the bias requires detailed simulations that include more observational effects than we consider here. Such a calibration exercise needs to be carried out for each specific WL mass estimation method, as the details of the method determine in part the expected scatter and bias. We present an iterative method for estimating mass M500c that can eliminate the bias for analyses of ground-based data.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/77dc8ab9b198ec5c910d9b7d38e5a79995453bd6

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Citations in the corpus

DEPENDENCE OF THE OUTER DENSITY PROFILES OF HALOS ON THEIR MASS ACCRETION RATE (2014, background): “For example, Becker & Kravtsov (2011) showed that typical cluster-sized halos exhibit deviations from the NFW form, and that NFW profile fits to shear profiles extended to large radii can result in sizeable systematic bias in weak lensing mass measurements (see also Oguri & Hamana 2011).”
ROBUST OPTICAL RICHNESS ESTIMATION WITH REDUCED SCATTER (2011, background): “…luminosity, which is the noisiest X-ray mass estimator, has a scatter of σln M|LX = 0.25–0.32 (Vikhlinin et al. 2009; Mantz et al. 2010).18 This is comparable to the scatter in halo mass at fixed weak-lensing mass, which is also estimated to be about σln M|WL = 0.25–0.30 (Becker & Kravtsov 2011).”
Weighing the giants – IV. Cosmology and neutrino mass (2014, methodology): “In the context of cosmological constraints, however, it is interesting to note that the constraint on intrinsic scatter in the mlens–m relation, 0.18 ± 0.05, is considerably tighter than the prior (0.2 ± 0.1) and in good agreement with simulation predictions (Becker & Kravtsov 2011).”
The Canadian Cluster Comparison Project: detailed study of systematics and updated weak lensing masses (2015, background): “The triaxial nature of cluster haloes, however, leads to an additional intrinsic scatter of ∼15–20 per cent (e.g. Corless & King 2007; Meneghetti et al. 2010; Becker & Kravtsov 2011).”
Cosmological Parameters from Observations of Galaxy Clusters (2011, background): “…estimators, working over optimized radial ranges and with good knowledge of the redshift distribution of the background population, weak lensing measurements are expected to provide almost unbiased results on the mean mass (Clowe, De Lucia & King 2004; Corless & King 2009; Becker & Kravtsov 2010).”
JOINT ANALYSIS OF CLUSTER OBSERVATIONS. II. CHANDRA/XMM-NEWTON X-RAY AND WEAK LENSING SCALING RELATIONS FOR A SAMPLE OF 50 RICH CLUSTERS OF GALAXIES (2012, methodology): “This bias level is lower than the 5%–10% that is usual for numerical simulations, which also have a typical scatter of 20%–30% (Becker & Kravtsov 2011; Bahé et al. 2012; Rasia et al. 2012; High et al. 2012); the actual amount of bias depends on the range of physical radii used in the weak lensing…”
Masses of Galaxy Clusters from Gravitational Lensing (2013, methodology): “Using numerical simulations Becker & Kravtsov (2011), however, show that the correlated structures are not a major source of uncertainty and that the main source of scatter in scaling relations between lensing mass and other indicators arises from the intrinsic triaxiality of dark matter halos…”
CLASH: JOINT ANALYSIS OF STRONG-LENSING, WEAK-LENSING SHEAR, AND MAGNIFICATION DATA FOR 20 GALAXY CLUSTERS (2015, background): “Numerical simulations suggest that these mass estimates tend to be biased low (by ∼ 5%–10%; see Meneghetti et al. 2010; Becker & Kravtsov 2011; Rasia et al. 2012) because local substructures that are abundant in cluster outskirts dilute the shear tangential to the cluster center.”
COSMOLOGICAL CONSTRAINTS FROM SUNYAEV–ZEL'DOVICH-SELECTED CLUSTERS WITH X-RAY OBSERVATIONS IN THE FIRST 178 deg2 OF THE SOUTH POLE TELESCOPE SURVEY (2011, background): “Numerical simulations have also led to a better understanding of systematic biases in cluster mass estimates derived from a broad range of cluster observables (e.g., Kravtsov et al. 2006; Jeltema et al. 2008; Stanek et al. 2010; Becker & Kravtsov 2011).”
Combined strong and weak lensing analysis of 28 clusters from the Sloan Giant Arcs Survey (2011, background): “Given the uncertainty from the non-linearity of the reduced shear and the the possible bias coming from the uncertainty of the outer mass profile (Oguri & Hamana 2011; Becker & Kravtsov 2011), we restrict tangential shear fitting in the range 0.158h−1Mpc < r < 3.16h−1Mpc.”
Weighing the Giants - I. Weak-lensing masses for 51 massive galaxy clusters: project overview, data analysis methods and cluster images (2012, methodology): “…different halo center definitions, such as center-ofmass (e.g. Lacey & Cole 1994), most bound particle or potential minimum (e.g. Meneghetti et al. 2010; Hilbert & White 2010), or highest density peak (Tinker et al. 2008; Becker & Kravtsov 2011) approximate different observational definitions.”
Lensing and x-ray mass estimates of clusters (simulations) (2012, background): “Becker & Kravtsov (2011), specifically, showed that the scatter in the weak-lensing masses of low-mass halos increases more than for highmass halos as a function of line-of-sight integration length because the high-mass halos generate more shear than the low-mass halos.”
Cosmology and astrophysics from relaxed galaxy clusters - II. Cosmological constraints (2014, background): “The lensing mass measurements themselves are expected to be unbiased (see Becker & Kravtsov 2011 and WtG).”
CLASH: WEAK-LENSING SHEAR-AND-MAGNIFICATION ANALYSIS OF 20 GALAXY CLUSTERS (2014, background): “This approach, however, has a disadvantage that the cluster mass estimates can be biased low by 5−10% (Meneghetti et al. 2010b; Becker & Kravtsov 2011; Rasia et al. 2012).”
Robust weak-lensing mass calibration of Planck galaxy clusters (2014, methodology): “…since the masses recovered by weak-lensing measurements are inherently noisy (the scatter in mass from typical ground-based studies is estimated to be ∼ 30 per cent; Becker & Kravtsov 2011), relatively large samples of clusters are required to determine the mass calibration to high precision.”
Weak Lensing Measurement of the Mass--Richness Relation of SDSS redMaPPer Clusters (2016, methodology): “We set σlnM|WL = 0.25 ± 0.05 based on the results by Becker & Kravtsov (2011), and σlnM|λ = 0.25 ± 0.05 as discussed earlier.”
Weighing the Giants – III. Methods and measurements of accurate galaxy cluster weak-lensing masses (2012, methodology): “Multiple authors (e.g. Becker & Kravtsov 2011; Oguri & Hamana 2011; Bahé et al. 2012) have shown that fitting an NFW profile to arbitrarily large projected radii can result in significant mass-e timate biases.”