Cluster mass calibration at high redshift: HST weak lensing analysis of 13 distant galaxy clusters from the South Pole Telescope Sunyaev–Zel'dovich Survey

Abstract

We present an HST/ACS weak gravitational lensing analysis of 13 massive highredshift (z median = 0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev-Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass-observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in V − I colour. Our estimate of the source redshift distribution is based on CANDELS data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the concentrationmass relation using simulations. In combination with temperature estimates from Chandra we constrain the normalisation of the mass-temperature scaling relation ln E(z)M 500c /10 14 M = A + 1.5 ln (kT /7.2keV) to A = 1.81 +0.24 −0.14 (stat.)±0.09(sys.), consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to c 200c = 5.6 +3.7 −1.8 .

The richness-to-mass relation of CAMIRA galaxy clusters from weak-lensing magnification in the Subaru Hyper Suprime-Cam survey

“…One of the most important tasks to carry out such a magnification analysis is to select a clean sample of background galaxies at sufficiently high redshift, with a very low level of contamination. A possible improvement in future is to include near-Infrared data to select higher-redshift background populations (Schrabback et al 2018). With the whole HSC-Wide coverage (≈ 1400 deg 2 ), we expect that the normalization of the N-M relation could be determined to better than 8% precision, which will allow us to place competitive cosmological constraints using galaxy clusters.…”

Scientific Synergy between LSST and Euclid

“…is high. Optical color selection from deep LSST photometry (here -< g z 0.4) is sufficient for selecting most of these distant background galaxies (see also Schrabback et al 2017). The plotted histograms show the expected source density for Euclid based on CANDELS/COSMOS photometric redshifts (Skelton et al 2014).…”

“…The required background source galaxies at  z 1.5 are still well resolved in the Euclid VIS data for shape measurements. Even if individual galaxy photo-z's may be too noisy, the faint high-redshift tail of the expected galaxy distribution can still be selected from deep LSST colors (and calibrated on the deep fields) with low to moderate contamination from the foreground and cluster galaxies (see Figure 1 and Schrabback et al 2017). This strategy is particularly effective (i) at high ecliptic latitudes, where the Euclid data are deeper because of lower zodiacal background, (ii) where deep photometry is available from LSST, and (iii) if new shape measurement techniques, which yield robust results for galaxies with lower S/N, are employed (e.g., Bernstein et al 2016).…”

Precise Mass Determination of SPT-CL J2106-5844, the Most Massive Cluster at z > 1

“…We use the published photo-z catalogs. Red solid line represents our color threshold (F606W − F814W < 1.0) while blue solid line shows the Schrabback et al (2018) threshold (F606W − F814W < 0.2). Three blue dashed lines indicate our experimental color thresholds whose impacts are shown in the middle and bottom panels.…”

“…Follow-up studies with SZ (e.g., Williamson et al 2011;Reichardt et al 2013;Bleem et al 2015) and X-ray (e.g., Amodeo et al 2016; Bartalucci et al 2017) observations consistently provided high masses for the system. Schrabback et al (2018) (hereafter S18) presented the first weak-lensing (WL) measurement of SPT2106 using the Advanced Camera for Surveys (ACS) in the Hubble Space Telescope (HST) data and obtained M 200c = 8.8 +5.0 −4.6 × 10 14 M . The central value of this measurement is somewhat lower than the previous non-WL estimates (e.g., ∼30% smaller than the F11 value).…”