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Galaxy And Mass Assembly (GAMA) : the halo mass of galaxy groups from maximum-likelihood weak lensing.

Han, J. and Eke, V. R. and Frenk, C. S. and Mandelbaum, R. and Norberg, P. and Schneider, M. D. and Peacock, J. A. and Jing, Y. and Baldry, I. and Bland-Hawthorn, J. and Brough, S. and Brown, M. J. I. and Liske, J. and Loveday, J. and Robotham, A. S. G. (2015) 'Galaxy And Mass Assembly (GAMA) : the halo mass of galaxy groups from maximum-likelihood weak lensing.', Monthly notices of the Royal Astronomical Society., 446 (2). pp. 1356-1379.


We present a maximum-likelihood weak-lensing analysis of the mass distribution in optically selected spectroscopic Galaxy Groups (G3Cv5) in the Galaxy And Mass Assembly (GAMA) survey, using background Sloan Digital Sky Survey (SDSS) photometric galaxies. The scaling of halo mass, Mh, with various group observables is investigated. Our main results are as follows. (1) The measured relations of halo mass with group luminosity, virial volume and central galaxy stellar mass, M*, agree very well with predictions from mock group catalogues constructed from a galform semi-analytical galaxy formation model implemented in the Millennium ΛCDM N-body simulation. (2) The measured relations of halo mass with velocity dispersion and projected half-abundance radius show weak tension with mock predictions, hinting at problems in the mock galaxy dynamics and their small-scale distribution. (3) The median Mh|M* measured from weak lensing depends more sensitively on the lognormal dispersion in M* at fixed Mh than it does on the median M*|Mh. Our measurements suggest an intrinsic dispersion of σlog(M*)∼ 0.15. (4) Comparing our mass estimates with those in the catalogue, we find that the G3Cv5 mass can give biased results when used to select subsets of the group sample. Of the various new halo-mass estimators that we calibrate using our weak-lensing measurements, group luminosity is the best single-proxy estimator of group mass.

Item Type:Article
Keywords:Gravitational lensing: weak, Methods: data analysis, Dark matter, Galaxies: clusters.
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Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:15 October 2014
Date deposited:11 February 2016
Date of first online publication:17 November 2014
Date first made open access:No date available

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