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On optical mass estimation methods for galaxy groups

Pearson, R.J.; Ponman, T.J.; Norberg, P.; Robotham, A.S.G.; Farr, W.M.

On optical mass estimation methods for galaxy groups Thumbnail


R.J. Pearson

T.J. Ponman

A.S.G. Robotham

W.M. Farr


We examine the performance of a variety of different estimators for the mass of galaxy groups, based on their galaxy distribution alone. We draw galaxies from the Sloan Digital Sky Survey for a set of groups and clusters for which hydrostatic mass estimates based on high-quality Chandra X-ray data are available. These are used to calibrate the galaxy-based mass proxies, and to test their performance. Richness, luminosity, galaxy overdensity, rms radius and dynamical mass proxies are all explored. These different mass indicators all have their merits, and we argue that using them in combination can provide protection against being misled by the effects of dynamical disturbance or variations in star formation efficiency. Using them in this way leads us to infer the presence of significant non-statistical scatter in the X-ray based mass estimates we employ. We apply a similar analysis to a set of mock groups derived from applying a semi-analytic galaxy formation code to the Millennium dark matter simulation. The relations between halo mass and the mass proxies differ significantly in some cases from those seen in the observational groups, and we discuss possible reasons for this.


Pearson, R., Ponman, T., Norberg, P., Robotham, A., & Farr, W. (2015). On optical mass estimation methods for galaxy groups. Monthly Notices of the Royal Astronomical Society, 449(3), 3082-3106.

Journal Article Type Article
Acceptance Date Mar 2, 2015
Publication Date May 21, 2015
Deposit Date Feb 3, 2016
Publicly Available Date Feb 12, 2016
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 449
Issue 3
Pages 3082-3106
Keywords Galaxies: groups: general.


Published Journal Article (2.7 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Author Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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