The Atacama Cosmology Telescope: Dynamical Masses and Scaling Relations for a Sample of Massive SunyaevZel'dovich Effect Selected Galaxy Clusters
Abstract
We present the first dynamical mass estimates and scaling relations for a sample of SunyaevZel'dovich effect (SZE) selected galaxy clusters. The sample consists of 16 massive clusters detected with the Atacama Cosmology Telescope (ACT) over a 455 deg^{2} area of the southern sky. Deep multiobject spectroscopic observations were taken to secure intermediateresolution (R ~ 700800) spectra and redshifts for ≈60 member galaxies on average per cluster. The dynamical masses M _{200c } of the clusters have been calculated using simulationbased scaling relations between velocity dispersion and mass. The sample has a median redshift z = 0.50 and a median mass M_{200c}\simeq 12\times 10^{14}\,h_{70}^{1}\,M_\odot with a lower limit M_{200c}\simeq 6\times 10^{14}\,h_{70}^{1}\,M_\odot, consistent with the expectations for the ACT southern sky survey. These masses are compared to the ACT SZE properties of the sample, specifically, the matchfiltered central SZE amplitude \widetilde{y_0}, the central Compton parameter y _{0}, and the integrated Compton signal Y _{200c }, which we use to derive SZEmass scaling relations. All SZE estimators correlate with dynamical mass with low intrinsic scatter (lsim 20%), in agreement with numerical simulations. We explore the effects of various systematic effects on these scaling relations, including the correlation between observables and the influence of dynamically disturbed clusters. Using the threedimensional information available, we divide the sample into relaxed and disturbed clusters and find that ~50% of the clusters are disturbed. There are hints that disturbed systems might bias the scaling relations, but given the current sample sizes, these differences are not significant; further studies including more clusters are required to assess the impact of these clusters on the scaling relations.
 Publication:

The Astrophysical Journal
 Pub Date:
 July 2013
 DOI:
 10.1088/0004637X/772/1/25
 arXiv:
 arXiv:1201.0991
 Bibcode:
 2013ApJ...772...25S
 Keywords:

 cosmic background radiation;
 cosmology: observations;
 galaxies: clusters: general;
 galaxies: distances and redshifts;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 15 pages, 4 figures. Accepted for publication in The Astrophysical Journal