Using archival X-ray observations and a log-normal 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 behavior 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 TXmeasurements are > 50% 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 TXscaling with halo mass from the Weighing the Giants program and richness-temperature covariance estimates from the LoCuSS sample, we derive the richnessconditioned scatter in mass, σlnM | λ = 0.30 ± 0.04(stat)± 0.09(sys), at an optical richness of approximately 70. Uncertainties in external parameters, particularly the slope and variance of the TX-mass relation and the covariance of TXand λRMat fixed mass, dominate the systematic error. The 95% confidence region from joint sample analysis is relatively broad, σlnM | λ ∈ [0.14, 0.55], or a factor ten in variance.
|Original language||English (US)|
|State||Published - Mar 19 2019|
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