Weak lensing analysis of codex clusters using dark energy camera legacy survey: mass–richness relation

Rykoff

Clerc

et al. 2020

A&A

Context. Large area catalogs of galaxy clusters constructed from ROSAT All-Sky Survey provide the basis for our knowledge of the population of clusters thanks to long-term multiwavelength efforts to follow up observations of these clusters. Aims. The advent of large area photometric surveys superseding previous, in-depth all-sky data allows us to revisit the construction of X-ray cluster catalogs, extending the study to lower cluster masses and higher redshifts and providing modeling of the selection function. Methods. We performed a wavelet detection of X-ray sources and made extensive simulations of the detection of clusters in the RASS data. We assigned an optical richness to each of the 24 788 detected X-ray sources in the 10 382 square degrees of the Baryon Oscillation Spectroscopic Survey area using red sequence cluster finder redMaPPer version 5.2 run on Sloan Digital Sky Survey photometry. We named this survey COnstrain Dark Energy with X-ray (CODEX) clusters. Results. We show that there is no obvious separation of sources on galaxy clusters and active galactic nuclei (AGN) based on the distribution of systems on their richness. This is a combination of an increasing number of galaxy groups and their selection via the identification of X-ray sources either by chance or by groups hosting an AGN. To clean the sample, we use a cut on the optical richness at the level corresponding to the 10% completeness of the survey and include it in the modeling of the cluster selection function. We present the X-ray catalog extending to a redshift of 0.6. Conclusions. The CODEX suvey is the first large area X-ray selected catalog of northern clusters reaching fluxes of 10−13 ergs s−1 cm−2. We provide modeling of the sample selection and discuss the redshift evolution of the high end of the X-ray luminosity function (XLF). Our results on z < 0.3 XLF agree with previous studies, while we provide new constraints on the 0.3 < z < 0.6 XLF. We find a lack of strong redshift evolution of the XLF, provide exact modeling of the effect of low number statistics and AGN contamination, and present the resulting constraints on the flat ΛCDM.

Section: Codex Catalogsupporting

confidence: 78%

CODEX clusters

Rykoff

Clerc

et al. 2020

A&A

“…Relatively flat slopes found in this and in LoCuSS work could be attributed to a combination of probing small-mass range and that intrinsic scatter in richness could increase with decreasing mass σ intr ln λ (m) ∝ 1/m. Although, our mass slope is only 1σ away from the slope found by McClintock et al (2019), a steeper slope of α = 1.0 +0.22 −0.22 was robustly established in low-z CODEX studies (Phriksee et al 2020), and was attributed to CODEX X-ray clusters being less prone to possible contamination by projected low mass groups of galaxies along line of sight than purely optically selected clusters, such as McClintock et al (2019).…”

Section: R E S U Lt S a N D Discussionsupporting

confidence: 49%

“…Our comparison to the results of the dynamical mass modelling, presented in Capasso et al (2019), indicate marginally lower mass for a given richness at richness values around 80. Considering other weak lensing calibrations, performed on X-ray clusters, we quote from Phriksee et al (2020) that at z < 0.15 the weak lensing calibration of CODEX clusters of Phriksee et al (2020) agrees well with Capasso et al (2019), while we find from Fig. 5 that LoCuSS (Mulroy et al 2019) results (0.15 < z < 0.3) are in significant tension with Capasso et al (2019).…”

Section: R E S U Lt S a N D Discussionmentioning

confidence: 57%

“…The richnesses of the clusters are estimated using the REDMAPPER algorithm and matched with DES Y3 RM catalog to calibrate the richness-mass relation, taking the SPT selection into account. This sample is closest to ours in terms of sample definition, as both X-ray and SZ signal require the presence of hot intracluster medium (ICM), which cleans the contamination of optical samples.In a recently published CODEX weak lensing analysis byPhriksee et al (2020), a mass-richness comparison was made toCapasso et al (2019), with 279 clusters in the optical richness range at 20 ≤ λ ≤ 110, and 0.1 ≤ z ≤ 0.2. They found an excellent agreement with both dynamical mass estimates and weak lensing mass estimates at z ≤ 0.15.We use the COLOSSUS PYTHON package(Diemer 2018) to convert the M 500c , and M 200m to M 200c when necessary, and evaluate the slope and intercept at M 200c, piv = 10 14.81 M , in order to compare our constraints with other results.…”

mentioning

confidence: 99%

See 1 more Smart Citation

CODEX weak lensing mass catalogue and implications on the mass–richness relation

Kiiveri

Monthly Notices of the Royal Astronomical Society

Erben

et al. 2020

The COnstrain Dark Energy with X-ray clusters (CODEX) sample contains the largest flux limited sample of X-ray clusters at 0.35 < z < 0.65. It was selected from ROSAT data in the 10 000 square degrees of overlap with BOSS, mapping a total number of 2770 high-z galaxy clusters. We present here the full results of the CFHT CODEX programme on cluster mass measurement, including a reanalysis of CFHTLS Wide data, with 25 individual lensing-constrained cluster masses. We employ lensfit shape measurement and perform a conservative colour–space selection and weighting of background galaxies. Using the combination of shape noise and an analytic covariance for intrinsic variations of cluster profiles at fixed mass due to large-scale structure, miscentring, and variations in concentration and ellipticity, we determine the likelihood of the observed shear signal as a function of true mass for each cluster. We combine 25 individual cluster mass likelihoods in a Bayesian hierarchical scheme with the inclusion of optical and X-ray selection functions to derive constraints on the slope α, normalization β, and scatter σln λ|μ of our richness–mass scaling relation model in log-space: ${\langle {\rm In}\,\, \lambda\!\!\mid\!\!\mu\rangle = \alpha\mu + \beta,} $ with μ = ln (M200c/Mpiv), and Mpiv = 1014.81M⊙. We find a slope $\alpha = 0.49^{+0.20}_{-0.15}$, normalization $\exp (\beta) = 84.0^{+9.2}_{-14.8}$, and $\sigma _{\ln \lambda | \mu } = 0.17^{+0.13}_{-0.09}$ using CFHT richness estimates. In comparison to other weak lensing richness–mass relations, we find the normalization of the richness statistically agreeing with the normalization of other scaling relations from a broad redshift range (0.0 < z < 0.65) and with different cluster selection (X-ray, Sunyaev–Zeldovich, and optical).

“…In order to constrain cosmology, a sample assembled using one (or more) of these methods also requires estimates of cluster mass. Arguably the most direct and accurate massmeasurement technique is weak lensing (Murata et al 2019;McClintock et al 2019a;Phriksee et al 2020;Umetsu 2020). In the case that lensing data are not available, cluster massproxies such as core-excised X-ray luminosity, integrated SZ effect signal, velocity dispersion, optical richness, etc.…”

mentioning

confidence: 99%

Cosmological constraints from CODEX galaxy clusters spectroscopically confirmed by SDSS-IV/SPIDERS DR16

Chitham

Comparat

Monthly Notices of the Royal Astronomical Society

et al. 2020

This paper presents a cosmological analysis based on the properties of X-ray selected clusters of galaxies from the CODEX survey which have been spectroscopically followed up within the SPIDERS programme as part of the sixteenth data release (DR16) of SDSS-IV. The cosmological sub-sample contains a total of 691 clusters over an area of 5,350deg2 with newly measured optical properties provided by a reanalysis of the CODEX source catalogue using redMaPPer and the DESI Legacy Imaging Surveys (DR8). Optical richness is used as a proxy for the cluster mass, and the combination of X-ray, optical and spectroscopic information ensures that only confirmed virialised systems are considered. Clusters are binned in observed redshift, $\tilde{z} \in \left[0.1, 0.6 \right)$ and optical richness, $\tilde{\lambda } \in \left[25, 148 \right)$ and the number of clusters in each bin is modelled as a function of cosmological and richness-mass scaling relation parameters. A high-purity sub-sample of 691 clusters is used in the analysis and best fit cosmological parameters are found to be $\Omega _{m_{0}}=0.34^{+0.09}_{-0.05}$ and $\sigma _8=0.73^{+0.03}_{-0.03}$. The redshift evolution of the self-calibrated richness-mass relation is poorly constrained due to the systematic uncertainties associated with the X-ray component of the selection function (which assumes a fixed X-ray luminosity-mass relation with h = 0.7 and $\Omega _{m_{0}}=0.30$). Repeating the analysis with the assumption of no redshift evolution is found to improve the consistency between both cosmological and scaling relation parameters with respect to recent galaxy cluster analyses in the literature.