Title: Clustering of CODEX clusters

Abstract

The clustering of galaxy clusters links the spatial nonuniformity of dark matter halos to the growth of the primordial spectrum of perturbations. The amplitude of the clustering signal is widely used to estimate the halo mass of astrophysical objects. The advent of cluster mass calibrations enables using clustering in cosmological studies. Aims. We analyze the autocorrelation function of a large contiguous sample of galaxy clusters, the Constrain Dark Energy with X-ray (CODEX) sample, in which we take particular care of cluster definition. These clusters were X-ray selected using the ROentgen SATellite All-Sky Survey and then identified as galaxy clusters using the code redMaPPer run on the photometry of the Sloan Digital Sky Survey. We develop methods for precisely accounting for the sample selection effects on the clustering and demonstrate their robustness using numerical simulations. Methods. Using the clean CODEX sample, which was obtained by applying a redshift-dependent richness selection, we computed the two-point autocorrelation function of galaxy clusters in the 0.1 < z < 0.3 and 0.3 < z < 0.5 redshift bins. We compared the bias in the measured correlation function with values obtained in numerical simulations using a similar cluster mass range. Results. By fitting a power law, we measured a correlation length r₀ = 18.7 ± 1.1 and slope γ = 1.98 ± 0.14 for the correlation function in the full redshift range. By fixing the other cosmological parameters to their nine-year Wilkinson Microwave Anisotropy Probe values, we reproduced the observed shape of the correlation function under the following cosmological conditions: Ω_m0 = $$0.22_{-0.03}^{+0.04}$$ and S₈ = σ₈(Ω_m0/0.3)0.5 = $$0.85_{-0.08}^{+0.10}$$ with estimated additional systematic errors of σ_Ωm0 = 0.02 and σS₈ = 0.20. We illustrate the complementarity of clustering constraints by combining them with CODEX cosmological constraints based on the X-ray luminosity function, deriving Ωm = 0.25 ± 0.01 and σ₈ = $$0.81_{-0.02}^{+0.01}$$ with an estimated additional systematic error of σ_Ωm0 = 0.07 and σ_σ8 = 0.04. The mass calibration and statistical quality of the mass tracers are the dominant source of uncertainty.

Authors:

Lindholm, V.  ^[1];

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Finoguenov, A. ^[2]; Comparat, J. ^[3]; Kirkpatrick, C. C. ^[1]; Rykoff, E. ^[4]; Clerc, N. ^[5]; Collins, C. ^[6]; Damsted, S. ^[2]; Ider Chitham, J. ^[3]; Padilla, N. ^[7]

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+ Show Author Affiliations

1. Univ. of Helsinki (Finland). Dept. of Physics; Univ. of Helsinki (Finland). Helsinki Institute of Physics
2. Univ. of Helsinki (Finland). Dept. of Physics
3. Max Planck Inst. fuer Extraterrestrische Physik, Garching (Germany)
4. Stanford Univ., CA (United States). Kavli Institute for Particle Astrophysics & Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States)
5. Univ. of Toulouse (France). IRAP
6. Liverpool John Moores Univ. (United Kingdom). Astrophysics Research Institute
7. Pontifica Universidad Catolica de Chile, Santiago (Chile). Instituto de Astrofisica

Publication Date:

Fri Jan 29 00:00:00 EST 2021

Research Org.:

SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1778216

Grant/Contract Number:  

AC02-76SF00515

Resource Type:

Accepted Manuscript

Journal Name:

Astronomy and Astrophysics

Additional Journal Information:

Journal Volume: 646; Journal ID: ISSN 0004-6361

Publisher:

EDP Sciences

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; galaxy clusters; cosmology