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Mass calibration of the CODEX cluster sample using SPIDERS spectroscopy - I. the richness-mass relation

Capasso, R, Mohr, JJ, Saro, A, Biviano, A, Clerc, N, Finoguenov, A, Grandis, S, Collins, CA, Erfanianfar, G, Damsted, S, Kirkpatrick, C and Kukkola, A (2019) Mass calibration of the CODEX cluster sample using SPIDERS spectroscopy - I. the richness-mass relation. Monthly Notices of the Royal Astronomical Society, 486 (2). pp. 1594-1607. ISSN 0035-8711

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We use galaxy dynamical information to calibrate the richness-mass scaling relation of a sample of 428 galaxy clusters that are members of the CODEX sample with redshifts up to z ∼ 0.7. These clusters were X-ray selected using the ROSAT All-Sky Survey (RASS) and then cross-matched to associated systems in the redMaPPer (the red sequence Matched-filter Probabilistic Percolation) catalogue from the Sloan Digital Sky Survey. The spectroscopic sample we analyse was obtained in the SPIDERS program and contains ∼7800 red member galaxies. Adopting NFW mass and galaxy density profiles and a broad range of orbital anisotropy profiles, we use the Jeans equation to calculate halo masses. Modelling the scaling relation as λαAλM200c Bλ(1 + z)γλ , we find the parameter constraints Aλ = 38.6+3.1 -4.1 ± 3.9, Bλ = 0.99+0.06 -0.07 ± 0.04, and γλ = -1.13+0.32 -0.34 ± 0.49, where we present systematic uncertainties as a second component. We find good agreement with previously published mass trends with the exception of those from stacked weak lensing analyses. We note that although the lensing analyses failed to account for the Eddington bias, this is not enough to explain the differences. We suggest that differences in the levels of contamination between pure redMaPPer and RASS + redMaPPer samples could well contribute to these differences. The redshift trend we measure is more negative than but statistically consistent with previous results. We suggest that our measured redshift trend reflects a change in the cluster galaxy red sequence (RS) fraction with redshift, noting that the trend we measure is consistent with but somewhat stronger than an independently measured redshift trend in the RS fraction. We also examine the impact of a plausible model of correlated scatter in X-ray luminosity and optical richness, showing it has negligible impact on our results.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2019 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: 0201 Astronomical and Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Date Deposited: 09 Jul 2019 08:08
Last Modified: 04 Sep 2021 09:11
DOI or ID number: 10.1093/mnras/stz931
URI: https://researchonline.ljmu.ac.uk/id/eprint/11006
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