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Subaru Weak-Lensing Survey II: Multi-Object Spectroscopy and Cluster Masses

Hamana, Takashi and Miyazaki, Satoshi and Kashikawa, Nobunari and Ellis, Richard S. and Massey, Richard J. and Refregier, Alexandre and Taylor, James E. (2009) Subaru Weak-Lensing Survey II: Multi-Object Spectroscopy and Cluster Masses. Publications of the Astronomical Society of Japan, 61 (4). pp. 833-872. ISSN 0004-6264. https://resolver.caltech.edu/CaltechAUTHORS:20091130-085831695

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Abstract

We present the first results of a multi-object spectroscopic campaign to follow up cluster candidates located via weak lensing. Our main goals are to search for spatial concentrations of galaxies that are plausible optical counterparts of the weak-lensing signals, and to determine the cluster redshifts from those of member galaxies. Around each of 36 targeted cluster candidates, we obtained 15–32 galaxy redshifts. For 28 of these targets, we confirmed a secure cluster identification, with more than five spectroscopic galaxies within a velocity of ±3000km s^(-1). This includes three cases where two clusters at different redshifts are projected along the same line-of-sight. In 6 of the 8 unconfirmed targets, we found multiple small galaxy concentrations at different redshifts, each containing at least three spectroscopic galaxies. The weak-lensing signal around those systems was thus probably created by the projection of groups or small clusters along the same line-of-sight. In both of the remaining two targets, a single small galaxy concentration was found. In some candidate super-cluster systems, we found additional evidence of filaments connecting the main density peak to an additional nearby structure. For a subsample of our most cleanly measured clusters, we investigated the statistical relation between their weak-lensing mass (M_(NFW), σ_(SIS)) and the velocity dispersion of their member galaxies (σ_ν), comparing our sample with optically and X-ray selected samples from the literature. Our lensing-selected clusters are consistent with σ_ν = σ_(SIS), with a similar scatter to that of optically and X-ray selected clusters. We also derived an empirical relation between the cluster mass and the galaxy velocity dispersion, M_(200)E(z) = 11.0 x 10^(14) x (σ_ν/1000km s^(-1))^(3.0) h^(-1)M_⊙, which is in reasonable agreement with predictions of N-body simulations in the ΛCDM cosmology.


Item Type:Article
Related URLs:
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http://pasj.asj.or.jp/v61/n4/610427/610427a.htmlPublisherUNSPECIFIED
ORCID:
AuthorORCID
Miyazaki, Satoshi0000-0001-9818-1513
Ellis, Richard S.0000-0001-7782-7071
Additional Information:© 2009 Astronomical Society of Japan. Received 2008 August 28; accepted 2009 May 15. We are very grateful to Subaru astronomers: Y. Ohyama, K. Aoki, and T. Hattori for their dedicated support of the FOCAS observing. Numerical computations presented in this paper were carried out on computer system at CfCA (Center for Computational Astrophysics) of the National Astronomical Observatory Japan. Data reduction and analysis were in part carried out on a general common-use computer system at ADAC (Astronomical Data Analysis Center) of the National Astronomical Observatory of Japan. This research was supported in part by the Grants-in-Aid from Monbu- Kagakusho and Japan Society of Promotion of Science: Project number 15340065 (TH&SM) and 21740202 (TH).
Funders:
Funding AgencyGrant Number
Monbu-Kagakusho and Japan Society of Promotion of Science15340065
Monbu-Kagakusho and Japan Society of Promotion of Science21740202
Subject Keywords:cosmology: dark matter; cosmology: large-scale structure of universe; cosmology: observations; galaxies: clusters: general
Issue or Number:4
Record Number:CaltechAUTHORS:20091130-085831695
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20091130-085831695
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16824
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:05 Jan 2010 19:05
Last Modified:09 Mar 2020 13:19

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