Mass calibration of distant SPT galaxy clusters through expanded weak lensing follow-up observations with HST, VLT &amp; Gemini-South

Schrabback, T.; Bocquet, S.; Sommer, M.; Zohren, H.; Busch, J. L. van den; Hernández-Martín, B.; Hoekstra, H.; Raihan, S. F.; Schirmer, M.; Applegate, D.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Dietrich, J. P.; Floyd, B.; Hilbert, S.; Hlavacek-Larrondo, J.; McDonald, M.; Saro, A.; Stark, A. A.; Weissgerber, N.

doi:10.48550/arxiv.2009.07591

Cited by 4 publications

(7 citation statements)

References 47 publications

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“…Some studies target more distant clusters (e.g. Chiu et al 2020;Schrabback et al 2020), but for our redshifts we can be sure that the shape of the BCG could be reliably measured in observations.…”

Section: General: the Simulated Samplementioning

confidence: 97%

Brightest Cluster Galaxies Trace Weak Lensing Mass Bias and Halo Triaxiality in The Three Hundred Project

Herbonnet,

Crawford,

Avestruz

et al. 2021

Preprint

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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 BCG and the halo. We find that haloes and their embedded BCGs are aligned, with an average ∼20 degree angle between their major axes. The bias in weak lensing cluster mass estimates correlates with the orientation of both the halo and the BCG. Mimicking observations, we compute the projected shape of the BCG, as a measure of the BCG orientation, and find that it is most strongly correlated to the weak-lensing mass for relaxed clusters. We also test a 2-dimensional cluster relaxation proxy measured from BCG mass isocontours. The concentration of stellar mass in the projected BCG core compared to the total stellar mass provides an alternative proxy for the BCG orientation. We find that the concentration does not correlate to the weak-lensing mass bias, but does correlate with the true halo mass. These results indicate that the BCG shape and orientation for large samples of relaxed clusters can provide information to improve weak-lensing mass estimates.

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Section: General: the Simulated Samplementioning

confidence: 97%

Brightest Cluster Galaxies Trace Weak Lensing Mass Bias and Halo Triaxiality in The Three Hundred Project

Herbonnet,

Crawford,

Avestruz

et al. 2021

Preprint

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“…We construct shear catalogs with different noise levels by varying the galaxy number density. For the main analysis, we use a value of 20 arcmin 2 for all fields, which approximately matches the setup for two-filter HST/ACS mosaics and clusters in the redshift interval 0.7 < 𝑧 < 1 in Schrabback et al (2021).…”

Section: Miscentring Distributionsmentioning

confidence: 99%

“…In addition to the miscentring distribution from convergence centers (previous subsection), we use two specific miscentring distributions derived for typical SZE observations and for typical X-ray center determinations. The distributions were derived based on the Magneticum Pathfinder Simulation (Dolag et al 2016), and are described in detail by Schrabback et al (2021). We summarize the most important points here.…”

Section: Including Miscentring In the Bias Estimationmentioning

confidence: 99%

“…Currently, uncertainties in such bi-★ E-mail: mnord@astro.uni-bonn.de (MWS) ases contribute significantly to the overall systematic error budget of mass-observable relations based on WL measurements (e.g. Applegate et al 2014;Mantz et al 2014;Planck Collaboration et al 2016;Schrabback et al 2018a;Dietrich et al 2019;Bocquet et al 2019;Schrabback et al 2021;McClintock et al 2019). It is thus crucial to obtain a better understanding of the mass bias and its dependencies.…”

Section: Introductionmentioning

confidence: 99%

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Weak lensing mass modeling bias and the impact of miscentring

Sommer,

Schrabback,

Applegate

et al. 2021

Preprint

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Parametric modeling of galaxy cluster density profiles from weak lensing observations leads to a mass bias, whose detailed understanding is critical in deriving accurate mass-observable relations for constraining cosmological models. Drawing from existing methods, we develop a robust framework for calculating this mass bias in one-parameter fits to simulations of dark matter halos. We show that our approach has the advantage of being independent of the absolute noise level, so that only the number of halos in a given simulation and the representativeness of the simulated halos for real clusters limit the accuracy of the bias estimation. While we model the bias as a log-normal distribution and the halos with a Navarro-Frenk-White profile, our method can be generalized to any bias distribution and parametric model of the radial mass distribution. We find that the log-normal assumption is not strictly valid in the presence of miscentring of halos. We investigate the use of cluster centers derived from weak lensing in the context of mass bias, and tentatively find that such centroids can yield sensible mass estimates if the convergence peak has a signal-to-noise ratio approximately greater than four. In this context we also find that the standard approach to estimating the positional uncertainty of weak lensing mass peaks using bootstrapping severely underestimates the true positional uncertainty for peaks with low signal-to-noise ratios. Though we determine the mass and redshift dependence of the bias distribution for a few experimental setups, our focus remains providing a general approach to computing such distributions.

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“…for the analysis of SPT clusters with weak-lensing mass calibration using data from the Dark Energy Survey, Bocquet et al in prep.). We note that a similar approach has been performed in Mantz et al (2015); Bocquet et al (2019); Dietrich et al (2019); Schrabback et al (2020).…”

Section: Introductionmentioning

confidence: 99%

Calibration of bias and scatter involved in cluster mass measurements using optical weak gravitational lensing

Grandis,

Bocquet,

Mohr

et al. 2021

Preprint

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Cosmological inference from cluster number counts is systematically limited by the accuracy of the mass calibration, i.e. the empirical determination of the mapping between cluster selection observables and halo mass. In this work we demonstrate a method to quantitatively determine the bias and uncertainties in weak-lensing mass calibration. To this end, we extract a library of projected matter density profiles from hydrodynamical simulations. Accounting for shear bias and noise, photometric redshift uncertainties, mis-centering, cluster member contamination, cluster morphological diversity, and line-of-sight projections, we produce a library of shear profiles. Fitting a one-parameter model to these profiles, we extract the so-called weak lensing mass 𝑀 WL . Relating the weak-lensing mass to the halo mass from gravity-only simulations with the same initial conditions as the hydrodynamical simulations allows us to estimate the impact of hydrodynamical effects on cluster number counts experiments. Creating new shear libraries for ∼1000 different realizations of the systematics, provides a distribution of the parameters of the weak-lensing to halo mass relation, reflecting their systematic uncertainty. This result can be used as a prior for cosmological inference. We also discuss the impact of the inner fitting radius on the accuracy, and determine the outer fitting radius necessary to exclude the signal from neighboring structures. Our method is currently being applied to different Stage III lensing surveys, and can easily be extended to Stage IV lensing surveys.

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Mass calibration of distant SPT galaxy clusters through expanded weak lensing follow-up observations with HST, VLT & Gemini-South

Cited by 4 publications

References 47 publications

Brightest Cluster Galaxies Trace Weak Lensing Mass Bias and Halo Triaxiality in The Three Hundred Project

Brightest Cluster Galaxies Trace Weak Lensing Mass Bias and Halo Triaxiality in The Three Hundred Project

Weak lensing mass modeling bias and the impact of miscentring

Calibration of bias and scatter involved in cluster mass measurements using optical weak gravitational lensing

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