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Mass variance from archival X-ray properties of Dark Energy Survey Year-1 galaxy clusters

A. Farahi, X. Chen, A. E. Evrard, D. Hollowood, R. Wilkinson, S. Bhargava, P. M. Giles, A. K. Romer, T. Jeltema, M. Hilton, A. Bermeo, J. A. Mayers, C. Vergara Cervantes, E. Rozo, E. S. Rykoff, C. A. Collins, M. Costanzi, S. Everett, A. R. Liddle, R. Mann, A. Mantz, P. J. Rooney, M. Sahlén, J. P. Stott, P. T. P. Viana, Y.-Y. Zhang, J. Annis, S. Avila, D. H. Brooks, E. Buckley-Geer, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, F. J. Castander, L. N. da Costa, J. De Vicente, S. Desai, H. T. Diehl, J. P. Dietrich, P. Doel, B. Flaugher, P. Fosalba, J. A. Frieman, J. García-Bellido, E. Gaztanaga, D. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, K. Honscheid, D. J. James, E. Krause, K. Kuehn, N. Kuropatkin, M. Lima, M. A. G. Maia, J. L. Marshall, P. Melchior, F. Menanteau, R. Miquel, R. L. C. Ogando, A. A. Plazas, E. Sanchez, V. Scarpine, M. Schubnell, S. Serrano, I. Sevilla-Noarbe, M. Smith, F. Sobreira, E. Suchyta, M. E. C. Swanson, G. Tarle, D. Thomas, D. L. Tucker, V. Vikram, A. R. Walker, J. Weller, DES Collaboration

Abstract
Using archival X-ray observations and a lognormal population model, we estimate constraints on the intrinsic scatter in halo mass at fixed optical richness for a galaxy cluster sample identified in Dark Energy Survey Year-One (DES-Y1) data with the redMaPPer algorithm. We examine the scaling behaviour of X-ray temperatures, TX, with optical richness, λRM, for clusters in the redshift range 0.2 < z < 0.7. X-ray temperatures are obtained from Chandra and XMM observations for 58 and 110 redMaPPer systems, respectively. Despite non-uniform sky coverage, the TX measurements are >50 per cent complete for clusters with λRM > 130. Regression analysis on the two samples produces consistent posterior scaling parameters, from which we derive a combined constraint on the residual scatter, σlnT|λ=0.275±0.019⁠. Joined with constraints for TX scaling with halo mass from the Weighing the Giants program and richness–temperature covariance estimates from the LoCuSS sample, we derive the richness-conditioned scatter in mass, σlnM|λ=0.30±0.04(stat)±0.09(sys)⁠, at an optical richness of approximately 100. Uncertainties in external parameters, particularly the slope and variance of the TX–mass relation and the covariance of TX and λRM at fixed mass, dominate the systematic error. The 95 per cent confidence region from joint sample analysis is relatively broad, σlnM|λ∈[0.14,0.55]⁠, or a factor 10 in variance.

Keywords
galaxies: clusters: general; X-rays: galaxies: clusters; Astrophysics - Cosmology and Nongalactic Astrophysics; Astrophysics - Astrophysics of Galaxies

Monthly Notices of the Royal Astronomical Society
Volume 490, Issue 3, Page 3341
2019 December

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia