TOWARD UNBIASED GALAXY CLUSTER MASSES FROM LINE-OF-SIGHT VELOCITY DISPERSIONS

We study the use of red-sequence-selected galaxy spectroscopy for unbiased estimation of galaxy cluster masses by using a publicly available simulated galaxy catalog. We explore the impact of selection using galaxy color, projected separation from the cluster center, galaxy luminosity, and spectrosc...

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Bibliographic Details
Published in:The Astrophysical journal 2013-07, Vol.772 (1), p.1-17
Main Authors: SARO, ALEX, Mohr, Joseph J, Bazin, Gurvan, Dolag, Klaus
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CALIBRATION
Clusters
COLOR
Dispersions
Galactic clusters
GALAXIES
GALAXY CLUSTERS
LUMINOSITY
MASS
Populations
RADIO NOISE
RED SHIFT
SAMPLING
Scatter
SIMULATION
SPECTROSCOPY
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Summary:We study the use of red-sequence-selected galaxy spectroscopy for unbiased estimation of galaxy cluster masses by using a publicly available simulated galaxy catalog. We explore the impact of selection using galaxy color, projected separation from the cluster center, galaxy luminosity, and spectroscopic redshift. We identify and characterize each of the following sources of bias and scatter in velocity dispersion at fixed mass: the intrinsic properties of halos in the form of halo triaxiality, sampling noise, the presence of multiple kinematic populations within the cluster, and the effect of interlopers. We show that even in red-sequence and spectroscopically selected galaxy samples, the interloper fraction is significant, and that the variations in the interloper population from cluster to cluster provide the dominant contribution to the velocity dispersion scatter at fixed mass. We present measurements of the total scatter in dispersion at fixed mass as a function of the number of redshifts. Results indicate that improvements in scatter are modest beyond samples of ~30 redshifts per cluster. Our results show that while cluster velocity dispersions extracted from a few dozen red-sequence-selected galaxies do not provide precise masses on a single cluster basis, an ensemble of cluster velocity dispersions can be combined to produce a precise calibration of a cluster survey-mass-observable relation. Currently, disagreements in the literature on simulated subhalo velocity dispersion-mass relations place a systematic floor on velocity dispersion mass calibration at the 5% level in dispersion.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/772/1/47