Dynamical Study of A1689 from Wide-Field VLT/VIMOS Spectroscopy: Mass Profile, Concentration Parameter, and Velocity Anisotropy
Abstract
We examine the dynamics structure of the rich cluster A1689, combining VLT/VIMOS spectroscopy with Subaru/Suprime-Cam imaging. The radial velocity distribution of ~500 cluster members is bounded by a pair of clearly defined velocity caustics, with a maximum amplitude of ~|4000| km s^(–1) at ≃ 300 h^(–1) kpc, beyond which the amplitude steadily declines, approaching zero velocity at a limiting radius of ~2 h^(–1) Mpc. We derive the three-dimensional velocity anisotropy and galaxy number density profiles using a model-independent method to solve the Jeans equation, simultaneously incorporating the observed velocity dispersion profile, the galaxy counts from deep Subaru imaging, and our previously derived cluster mass profile from a joint lensing and X-ray analysis. The velocity anisotropy is found to be predominantly radial at large radius, becoming increasingly tangential towards the center, in accord with expectations. We also analyze the galaxy data independently of our previous analysis using two different methods: The first is based on a solution of the Jeans equation assuming an Navarro-Frenk-White (NFW) form for the mass distribution, whereas in the second method the caustic amplitude is used to determine the escape velocity. The cluster virial mass derived by both of these dynamical methods is in good agreement with results from our earlier lensing and X-ray analysis. We also confirm the high NFW concentration parameter, with results from both methods combined to yield c_(vir) > 13 (1σ). The inferred virial radius is consistent with the limiting radius where the caustics approach zero velocity and where the counts of cluster members drop off, suggesting that infall onto A1689 is currently not significant.
Additional Information
© 2009 American Astronomical Society. Print publication: Issue 2 (2009 August 20); received 2009 January 7; accepted for publication 2009 June 17; published 2009 July 31. We thank Oliver Czoske for providing the redshift survey information for A1689 and for many helpful discussions. We also acknowledge discussions with Sharon Sadeh, Antonaldo Diaferio, Masataka Fukugita, Hagai Netzer, and the referee for useful comments. We wish to thank the referee for a thorough reading of a previous version of the paper, and for several useful suggestions. This paper was partly written while D.L. and T.B. were visitors of the Institute for the Physics and Mathematics of the Universe, University of Tokyo, which we thank for its generous hospitality. R.B. is grateful for support from the ICRR in Tokyo, Japan, the Moore Distinguished Scholar program at Caltech, and the John Simon Guggenheim Memorial Foundation. K.U. is partially supported by the National Science Council of Taiwan under the grant NSC97-2112-M-001-020-MY3.Attached Files
Published - Lemze2009p5724Astrophys_J.pdf
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Additional details
- Eprint ID
- 15428
- Resolver ID
- CaltechAUTHORS:20090828-153619884
- ICRR, Tokyo, Japan
- Moore Distinguished Scholar Program, Caltech
- John Simon Guggenheim Memorial Foundation
- NSC97-2112-M-001-020-MY3
- National Science Council of Taiwan
- Created
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2009-09-11Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field