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Published March 1995 | Published + Submitted
Journal Article Open

Gravitational lensing of distant field galaxies by rich clusters - II. Cluster mass distributions

Abstract

We construct a photometric catalogue of very faint galaxies (I ≲ 25.5) using deep CCD images taken with the 4.2-m William Herschel telescope of fields centred on two distant X-ray-luminous clusters: 1455+22 (z_(cl) = 0.26) and 0016+16 (z_(cl) = 0.55). Using a non-parametric procedure developed by Kaiser & Squires, we analyse the statistical image distortions in our samples to derive two-dimensional projected mass distributions for the clusters. The mass maps of 1455+22 and 0016+16 are presented at effective resolutions of 135 and 200 kpc, respectively (for H₀=50 km s⁻¹ Mpc⁻¹, q₀=0.5), with peak signal-to-noise ratios per resolution element of 17 and 14. Although the absolute normalization of these mass maps depends on the assumed redshift distribution of the I ≲ 25.5 field galaxies used as probes, the maps should be reliable on a relative scale and will trace the cluster mass regardless of whether it is baryonic or non-baryonic. We compare our 2D mass distributions on scales up to ∼1 Mpc with those defined by the spatial distribution of colour-selected cluster members and with deep high-resolution X-ray images of the hot intracluster gas. Despite the different cluster structures - one is cD-dominated and the other is not - in both cases the form of the mass distribution derived from the lensing signal is strikingly similar to that traced by both the cluster galaxies and the hot X-ray gas. We find some evidence for a greater central concentration of dark matter with respect to the galaxies. The overall similarity between the distribution of total mass and that defined by the baryonic components presents a significant new observational constraint on the nature of dark matter and the evolutionary history of rich clusters.

Additional Information

© 1995 Royal Astronomical Society. Provided by the NASA Astrophysics Data System. Accepted 1994 September 30. Received 1994 September 2; in original form 1994 February 24. Published: 15 March 1995. We wish to acknowledge the pioneering work of Tony Tyson and the Toulouse group led by Bernard Fort who first introduced us to the exciting possibilities gravitational lensing offers in cosmology. We thank Nick Kaiser and Jordi Miralda-Escude for extensive discussions on the subject of lensing. We also acknowledge useful discussions with Tereasa Brainerd, Carlos Frenk, Jean-Paul Kneib and Chris Kochanek. The support of the La Palma staff and especially Dave Carter is also gratefully acknowledged. This work was supported by the PPARC.

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Published - mnras273-02777.pdf

Submitted - 9402049.pdf

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September 15, 2023
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