Incorporating galaxy cluster triaxiality in stacked cluster weak lensing analyses
Zhuowen Zhang, Hao-Yi Wu, Yuanyuan Zhang, Joshua Frieman, Chun-Hao To, Joseph DeRose, Matteo Costanzi, Risa H. Wechsler, Susmita Adhikari, Eli Rykoff, Tesla Jel… 展开作者
Zhuowen Zhang, Hao-Yi Wu, Yuanyuan Zhang, Joshua Frieman, Chun-Hao To, Joseph DeRose, Matteo Costanzi, Risa H. Wechsler, Susmita Adhikari, Eli Rykoff, Tesla Jeltema, August Evrard, Eduardo Rozo
Counts of galaxy clusters offer a high-precision probe of cosmology, but control of systematic errors will determine the accuracy of this measurement. Using Buzzard simulations, we quantify one such systematic, the triaxiality distribution of clusters identified with the redMaPPer optical cluster finding algorithm, which was used in the Dark Energy Survey Year-1 (DES Y1) cluster cosmology analysis. We test whether redMaPPer selection biases the clusters' shape and orientation and find that it only biases orientation, preferentially selecting clusters with their major axes oriented along the line of sight. Modeling the richness-mass relation as a log-linear relation, we find that the log-richness amplitude $\ln(A)$ is boosted from the lowest to highest orientation bin with a significance of $14σ$, while the orientation dependence of the richness-mass slope and intrinsic scatter is minimal. We also find that the weak lensing shear-profile ratios of cluster-associated dark halos in different orientation bins resemble a "bottleneck" shape that can be quantified with a Cauchy function. We test the correlation of orientation with two other leading systematics in cluster cosmology -- miscentering and projection -- and find a null correlation. Analytic templates for the triaxiality bias of observed-richness and lensing profiles are mapped as corrections to the observable of richness-binned lensing profiles for redMaPPer clusters. The resulting mass bias confirms the DES Y1 finding that triaxiality is a leading source of bias in cluster cosmology. However, the richness-dependence of the bias confirms that triaxiality does not fully resolve the tension at low-richness between DES Y1 cluster cosmology and other probes. Our model can be used for quantifying the impact of triaxiality bias on cosmological constraints for upcoming weak lensing surveys of galaxy clusters.
Galaxy clusters have a triaxial matter distribution. The weak-lensing signal, an important part in cosmological studies, measures the projected mass of all matter along the line-of-sight, and therefore changes with the orientation of the cluster. Studies suggest that the shape of the brightest cluster galaxy (BCG) in the centre of the cluster traces the underlying halo shape, enabling a method to account for projection effects. We use 324 simulated clusters at four redshifts between 0.1 and 0.6 from `The Three Hundred Project' to quantify correlations between the orientation and shape of the B…
CHEX-MATE: The Impact of Triaxiality and Orientation on Planck SZ Cluster Selection and Weak Lensing Mass Measurements
California Institute of Technology（加州理工学院）；IRFU, CEA, Université Paris-Saclay（IRFU，CEA，巴黎萨克雷大学）；Smithsonian Astrophysical Observatory（史密森尼天体物理台）；Department of Physics, Korea Advanced Institute of Science and Technology (KAIST)（韩国科学技术院物理系）；Department of Astronomy, University of Geneva（日内瓦大学天文系）；Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia（摩德纳和雷焦艾米利亚大学物理、信息学和数学系）；INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano（意大利国家天体物理研究所米兰空间天体物理学与宇宙物理学研究所）
The imprints of large-scale structures on the Cosmic Microwave Background can be studied via the CMB lensing and Integrated Sachs-Wolfe (ISW) signals. In particular, the stacked ISW signal around supervoids has been claimed in several works to be anomalously high. In this study, we find cluster and void superstructures using four tomographic redshift bins with $0<z<0.8$ from the DESI Legacy Survey, and measure the stacked CMB lensing and ISW signals around them. To compare our measurements with $Λ$CDM model predictions, we construct a mock catalogue with matched galaxy number density and bias,…
Unbiased and precise mass calibration of galaxy clusters is crucial to fully exploit galaxy clusters as cosmological probes. Stacking of weak lensing signal allows us to measure observable-mass relations down to less massive halos halos without extrapolation. We propose a Bayesian inference method to constrain the intrinsic scatter of the mass proxy in stacked analyses. The scatter of the stacked data is rescaled with respect to the individual scatter based on the number of binned clusters. We apply this method to the galaxy clusters detected with the AMICO (Adaptive Matched Identifier of Clus…
Stacked lensing is a powerful means of measuring the average mass distribution around large-scale structure tracers. There are two stacked lensing estimators used in the literature, denoted as $ΔΣ$ and $γ_+$, which are related as $ΔΣ=Σ_{\rm cr}γ_+$, where $Σ_{\rm cr}(z_l,z_s)$ is the critical surface mass density for each lens-source pair ($z_l$ and $z_s$ are lens and source redshifts, respectively). In this paper we derive a formula for the covariance matrix of $ΔΣ$-estimator focusing on `weight' function to improve the signal-to-noise ($S/N$). We assume that the lensing fields and the distri…
Cosmological constraints from current and upcoming galaxy cluster surveys are limited by the accuracy of cluster mass calibration. In particular, optically identified galaxy clusters are prone to selection effects that can bias the weak lensing mass calibration. We investigate the selection bias of the stacked cluster lensing signal associated with optically selected clusters, using clusters identified by the redMaPPer algorithm in the Buzzard simulations as a case study. We find that at a given cluster halo mass, the residuals of redMaPPer richness and weak lensing signal are positively corre…
Dark matter halos represent the highest density peaks in the matter distribution. Conversely, cosmic voids are under-dense patches of the universe. Probing the mass distribution of the universe requires various approaches, including weak gravitational lensing that subtly modifies the shape of distant sources, and Doppler lensing that changes the apparent size and magnitude of objects due to peculiar velocities. In this work, we adopt both gravitational and Doppler lensing effects to study the underlying matter distribution in and around cosmic voids/halos. We use the relativistic $N$-body code…
We present a cosmological analysis of abundances and stacked weak-lensing profiles of galaxy clusters, exploiting the AMICO KiDS-DR3 catalogue. The sample consists of 3652 galaxy clusters with intrinsic richness $λ^*\geq20$, over an effective area of 377 deg$^2$, in the redshift range $z\in[0.1,\,0.6]$. We quantified the purity and completeness of the sample through simulations. The statistical analysis has been performed by simultaneously modelling the comoving number density of galaxy clusters and the scaling relation between the intrinsic richnesses and the cluster masses, assessed through …
An essential aspect of cosmic voids is that these underdense regions provide complementary information about the properties of our Universe. Unlike dense regions, voids are avoided by matter and are less contaminated by baryonic processes. The first step to understanding the properties of cosmic voids is to correctly infer their mass profiles. In the literature, various techniques have been implemented. In this paper, we review them and implement a new technique that is based on Doppler lensing. We use a relativistic $N$-body code, \textsc{Gevolution}, to generate cosmological mass perturbatio…
Stacked strong and weak lensing united: Improved measurement of the stellar and dark matter distributions in massive early-type galaxies at $z\sim 0.5$
Department of Physics, Graduate School of Science, Chiba University（千叶大学理学研究科物理学系）；Center for Frontier Science, Chiba University（千叶大学前沿科学中心）
An optical cluster finder inevitably suffers from projection effects, where it misidentifies a superposition of galaxies in multiple halos along the line-of-sight as a single cluster. Using mock cluster catalogs built from cosmological N-body simulations, we quantify the impact of these projection effects with a particular focus on the observables of interest for cluster cosmology, namely the cluster lensing and the cluster clustering signals. We find that "observed" clusters, i.e. clusters identified by our cluster finder algorithm, exhibit lensing and clustering signals that deviate from exp…
Constraining Galaxy Cluster Triaxiality via Weak Lensing --- I. Preparation for the Rubin Data Beyond Leading Order
NSF-DOE Vera C. Rubin Observatory / SLAC National Accelerator Laboratory（NSF-DOE薇拉·C·鲁宾天文台/SLAC国家加速器实验室）；Kavli Institute for Particle Astrophysics and Cosmology, Stanford University（斯坦福大学卡弗里粒子天体物理学与宇宙学研究所）；Department of Physics and Astronomy, Stony Brook University（纽约州立大学石溪分校物理与天文学系）；Carnegie Mellon University（卡内基梅隆大学）；Faculty of Physics, Ludwig-Maximilians-Universit at（路德维希-马克西米利安大学物理学院）；University of Michigan（密歇根大学）；NSF’s National Optical-Infrared Astronomy Research Laboratory（美国国家光学红外天文研究实验室）；Istituto Nazionale di Astrofisica（意大利国家天体物理研究所）；Univ. Grenoble Alpes, CNRS, LPSC-IN2P3（格勒诺布尔阿尔卑斯大学/CNRS/LPSC-IN2P3）；Department of Physics, Brown University（布朗大学物理系）
Context. The large-scale mass distribution around dark matter haloes hosting galaxy clusters provides sensitive cosmological information. Aims. In this work, we make use of a large photometric galaxy cluster sample, constructed from the public Third Data Release of the Kilo-Degree Survey, and the corresponding shear signal, to assess cluster masses and test the concordance $Λ$-cold dark matter ($Λ$CDM) model. In particular, we study the weak gravitational lensing effects on scales beyond the cluster virial radius, where the signal is dominated by correlated and uncorrelated matter density dist…
Cluster weak lensing is a sensitive probe of cosmology, particularly the amplitude of matter clustering $σ_8$ and matter density parameter $Ω_m$. The main nuisance parameter in a cluster weak lensing cosmological analysis is the scatter between the true halo mass and the relevant cluster observable, denoted $σ_{\ln Mc}$. We show that combining the cluster weak lensing observable $ΔΣ$ with the projected cluster-galaxy cross-correlation function $w_{p,cg}$ and galaxy auto-correlation function $w_{p,gg}$ can break the degeneracy between $σ_8$ and $σ_{\ln Mc}$ to achieve tight, percent-level const…
For more than two decades, the Navarro, Frenk, and White (NFW) model has stood the test of time; it has been used to describe the distribution of mass in galaxy clusters out to their outskirts. Stacked weak lensing measurements of clusters are now revealing the distribution of mass out to and beyond their virial radii, where the NFW model is no longer applicable. In this study we assess how well the parameterised Diemer & Kravstov (DK) density profile describes the characteristic mass distribution of galaxy clusters extracted from cosmological simulations. This is determined from stacked synth…
Weak-lensing measurements of the masses of galaxy clusters are commonly based on the assumption of spherically symmetric density profiles. Yet, the cold dark matter model predicts the shapes of dark matter halos to be triaxial. Halo triaxiality, and the orientation of the major axis with respect to the line of sight, are expected to be the leading cause of intrinsic scatter in weak-lensing mass measurements. The shape of central cluster galaxies (Brightest Cluster Galaxies; BCGs) is expected to follow the shape of the dark matter halo. Here we investigate the use of BCG ellipticity as predicto…
We present a measurement of average histograms of line-of-sight velocities over pairs of galaxies and galaxy clusters. Since the histogram can be measured at different galaxy-cluster separations, this observable is commonly referred to as the stacked phase-space density. We formulate the stacked phase-space density based on a halo-model approach so that the model can be applied to real samples of galaxies and clusters. We examine our model by using an actual sample of massive clusters with known weak-lensing masses and spectroscopic observations of galaxies around the clusters. A likelihood an…
Impact of projection-induced optical selection bias on the weak lensing mass calibration of galaxy clusters
Boise State University（博伊西州立大学）；Southern Methodist University（南方卫理公会大学）；Instituto de Física Teórica (IFT), UAM–CSIC（马德里自治大学-西班牙国家研究委员会理论物理研究所）；Case Western Reserve University（凯斯西储大学）；University of Chicago（芝加哥大学）；University of California, Santa Cruz（加州大学圣克鲁兹分校）
Low density regions are less affected by the nonlinear structure formation and baryonic physics. They are ideal places for probing the nature of dark energy, a possible explanation for the cosmic acceleration. Unlike void lensing, which requires identifications of individual voids, we study the stacked lensing signals around the low-density-positions (LDP), defined as places that are devoid of foreground bright galaxies in projection. The method allows a direct comparison with numerical results by drawing correspondence between the bright galaxies with halos. It leads to lensing signals that a…
Using $\sim$140 deg$^2$ Subaru Hyper Suprime-Cam (HSC) survey data, we stack the weak lensing (WL) signal around five Planck clusters found within the footprint. This yields a 15$σ$ detection of the mean Planck cluster mass density profile. The five Planck clusters span a relatively wide mass range, $M_{\rm WL,500c} = (2-30)\times10^{14}\,M_\odot/h$ with a mean mass of $M_{\rm WL,500c} = (4.15\pm0.61)\times10^{14}\,M_\odot/h$. The ratio of the stacked Planck Sunyaev-Zel'dovich (SZ) mass to the stacked WL mass is $ \langle M_{\rm SZ}\rangle/\langle M_{\rm WL}\rangle = 1-b = 0.80\pm0.14$. This m…
Galaxy clusters are biased tracers of the underlying matter density field. At very large radii beyond about 10 Mpc/\textit{h}, the shear profile shows evidence of a second-halo term. This is related to the correlated matter distribution around galaxy clusters and proportional to the so-called halo bias. We present an observational analysis of the halo bias-mass relation based on the AMICO galaxy cluster catalog, comprising around 7000 candidates detected in the third release of the KiDS survey. We split the cluster sample into 14 redshift-richness bins and derive the halo bias and the virial m…
Scaling relations trace the formation and evolution of galaxy clusters. We exploited multi-wavelength surveys -- the XXL survey at \emph{XMM-Newton} in the X-ray band, and the Hyper Suprime-Cam Subaru Strategic Program for optical weak lensing -- to study an X-ray selected, complete sample of clusters and groups. The scalings of gas mass, temperature, and soft-band X-ray luminosity with the weak lensing mass show imprints of radiative cooling and AGN feedback in groups. From the multi-variate analysis, we found some evidence for steeper than self-similar slopes for gas mass ($β_{m_\text{g}|m}=…
We present weak lensing mass estimates for a sample of 458 galaxy clusters from the redMaPPer Sloan Digital Sky Survey DR8 catalogue using Hyper Suprime-Cam weak lensing data. We develop a method to quickly estimate cluster masses from weak lensing shear and use this method to estimate weak lensing masses for each of the galaxy clusters in our sample. Subsequently, we constrain the mass-richness relation as well as the intrinsic scatter between the cluster richness and the measured weak lensing masses. When calculating the mass-richness relation for all clusters with a richness $λ>20$, we find…
Weak gravitational lensing depends on the integrated mass along the line of sight. Baryons contribute to the mass distribution of galaxy clusters and the resulting mass estimates from lensing analysis. We use the cosmo-OWLS suite of hydrodynamic simulations to investigate the impact of baryonic processes on the bias and scatter of weak lensing mass estimates of clusters. These estimates are obtained by fitting NFW profiles to mock data using MCMC techniques. In particular, we examine the difference in estimates between dark matter-only runs and those including various prescriptions for baryoni…
Comparison of an X-ray selected sample of massive lensing clusters with the MareNostrum Universe LCDM simulation
一个长期存在的问题是星系团的强透镜效应，与“标准”宇宙学模型框架中的预测相比，观测到的巨大引力弧的高比率。最近，很少有其他的理论预期和观测之间的不一致，声称这方面的爱因斯坦环的大尺寸和高浓度的少数集群具有强透镜功能。所有这些问题都一致表明，观测到的星系团可能是比预期更强的引力透镜。我们使用从MareNostrum宇宙中提取的星系团建立模拟目录，通过它们的X射线通量选择星系团。我们使用这些物体来估计在$z>0.5$上的12个MACS集群样本的透镜截面、爱因斯坦环和浓度的概率分布，这些样本在Ebeling et al.（2007）中提出，并在Zitrin et al.（2010）中进行了讨论。我们发现，模拟集群产生的$\sim 50%$少弧比观察到的集群。爱因斯坦环尺寸分布的中位数在模拟和观测之间相差$\sim 25%$。我们估计，由于集群的三轴性和方向偏差影响的镜头与最大的横截面，从透镜分析推断的个别MACS集群的浓度应高达$\sim 2$的一个因素大于预期的$Λ$ CDM模型。弧统计，爱因斯坦环，并在强透镜团簇的浓度问题得到缓解，但没有解决的基础上，我们的分析。然而，由于大多数用于模拟MACS集群的多个图像系统缺乏红移，这项工作的结果将需要用更多的数据来验证。即将到来的CLASH程序将为扩展我们的比较提供一个理想的样本。
We constrain the scaling relation between optical richness ($λ$) and halo mass ($M$) for a sample of SDSS redMaPPer galaxy clusters within the context of the {\it Planck} cosmological model. We use a forward modeling approach where we model the probability distribution of optical richness for a given mass, $P(\ln λ| M)$. To model the abundance and the stacked lensing profiles, we use an emulator specifically built to interpolate the halo mass function and the stacked lensing profile for an arbitrary set of halo mass and redshift, which is calibrated based on a suite of high-resolution $N$-body…
The splashback radius $r_\text{sp}$ separates the physical regimes of collapsed and infalling material around massive dark matter haloes. In cosmological simulations, this location is associated with a steepening of the spherically averaged density profile $ρ(r)$. In this work, we measure the splashback feature in the stacked weak gravitational lensing signal of $27$ massive clusters from the Cluster Canadian Comparison Project with careful control of residual systematics effects. We find that the shear introduced by the presence of additional structure along the line of sight significantly af…
