Document Type
Article
Publication Date
3-1-2016
Keywords
Cosmology: observations, Galaxies: clusters: general, Galaxies: distances and redshifts, Galaxies: kinematics and dynamics
Abstract
We estimate cluster masses and velocity dispersions for 123 clusters from optical spectroscopy to compare the Sunyaev–Zeldovich (SZ) mass proxy and dynamical masses. Our new survey, HeCS-SZ (Hectospec Cluster Survey of SZ-selected clusters), includes 7721 new or remeasured redshifts from MMT/Hectospec observations of 21 SZ-selected clusters at redshifts z = 0.05–0.20. We supplement the Hectospec data with spectra from the Sloan Digital Sky Survey (SDSS) and cluster data from the Cluster Infall Regions in SDSS project and the Hectospec Cluster Survey, our Hectospec survey of clusters selected by X-ray flux. We measure the scaling relation between velocity dispersion and SZ mass estimates from the integrated Compton parameter for an SZ-complete sample of 83 clusters. The observed relation agrees very well with a simple virial scaling from mass (based on SZ) to velocity dispersion. The SZ mass estimates (calibrated with hydrostatic X-ray mass estimates) are not significantly biased compared to dynamical mass estimates under the assumption of small velocity bias of galaxies compared to dark matter particles. Significant mass bias in SZ mass estimates could relieve tension between cosmological results from Planck SZ cluster counts and Planck CMB data. In principle, SZ mass bias and velocity bias of galaxies could conspire to yield good agreement, but the required velocity bias is , outside the range of recent models of velocity bias in the literature. More likely, SZ mass bias and velocity bias are both small, and the tension between SZ cluster counts and CMB data requires another explanation.
Publication Title
The Astrophysical Journal
Volume
819
Issue
1
DOI
10.3847/0004-637X/819/1/63
Required Publisher's Statement
© 2016 The American Astronomical Society
http://dx.doi.org/10.3847/0004-637X/819/1/63
The publisher's version of the article: http://iopscience.iop.org/article/10.3847/0004-637X/819/1 /63/meta;jsessionid=F253C7065449574EB562E0081BDA03DC.c4.iopscience.cld.iop.org#top
Recommended Citation
Rines, Kenneth J.; Geller, Margaret J.; Diaferio, Antonaldo; and Hwang, Ho Seong, "HeCS-SZ: The Hectospec Survey of Sunyaev-Zeldovich-Selected Clusters" (2016). Physics & Astronomy. 25.
https://cedar.wwu.edu/physicsastronomy_facpubs/25
Subjects - Topical (LCSH)
Galaxies--Clusters; Galaxies--Evolution; Stars--Observations
Genre/Form
articles
Type
Text
Language
English
Format
application/pdf