M.R. George
Galaxies in x-ray groups. II. A weak lensing study of halo centering
George, M.R.; Leauthaud, A.; Bundy, K.; Finoguenov, A.; Ma, C.-P.; Rykoff, E.S.; Tinker, J.L.; Wechsler, R.H.; Massey, R.; Mei, S.
Authors
A. Leauthaud
K. Bundy
A. Finoguenov
C.-P. Ma
E.S. Rykoff
J.L. Tinker
R.H. Wechsler
Professor Richard Massey r.j.massey@durham.ac.uk
Professor
S. Mei
Abstract
Locating the centers of dark matter halos is critical for understanding the mass profiles of halos, as well as the formation and evolution of the massive galaxies that they host. The task is observationally challenging because we cannot observe halos directly, and tracers such as bright galaxies or X-ray emission from hot plasma are imperfect. In this paper, we quantify the consequences of miscentering on the weak lensing signal from a sample of 129 X-ray-selected galaxy groups in the COSMOS field with redshifts 0 < z < 1 and halo masses in the range 1013-1014 M ☉. By measuring the stacked lensing signal around eight different candidate centers (such as the brightest member galaxy, the mean position of all member galaxies, or the X-ray centroid), we determine which candidates best trace the center of mass in halos. In this sample of groups, we find that massive galaxies near the X-ray centroids trace the center of mass to lsim 75 kpc, while the X-ray position and centroids based on the mean position of member galaxies have larger offsets primarily due to the statistical uncertainties in their positions (typically ~50-150 kpc). Approximately 30% of groups in our sample have ambiguous centers with multiple bright or massive galaxies, and some of these groups show disturbed mass profiles that are not well fit by standard models, suggesting that they are merging systems. We find that halo mass estimates from stacked weak lensing can be biased low by 5%-30% if inaccurate centers are used and the issue of miscentering is not addressed.
Citation
George, M., Leauthaud, A., Bundy, K., Finoguenov, A., Ma, C., Rykoff, E., …Mei, S. (2012). Galaxies in x-ray groups. II. A weak lensing study of halo centering. Astrophysical Journal, 757(1), Article 2. https://doi.org/10.1088/0004-637x/757/1/2
Journal Article Type | Article |
---|---|
Publication Date | Sep 20, 2012 |
Deposit Date | Mar 21, 2013 |
Publicly Available Date | Feb 11, 2015 |
Journal | Astrophysical Journal |
Print ISSN | 0004-637X |
Electronic ISSN | 1538-4357 |
Publisher | American Astronomical Society |
Peer Reviewed | Peer Reviewed |
Volume | 757 |
Issue | 1 |
Article Number | 2 |
DOI | https://doi.org/10.1088/0004-637x/757/1/2 |
Keywords | Cosmology: observations, Galaxies: clusters: general, Galaxies: groups: general, Gravitational lensing: weak. |
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Copyright Statement
© 2012. The American Astronomical Society. All rights reserved.
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