EDP Sciences
Free access
Volume 369, Number 1, April I 2001
Page(s) 16 - 25
Section Cosmology
DOI http://dx.doi.org/10.1051/0004-6361:20010093

A&A 369, 16-25 (2001)
DOI: 10.1051/0004-6361:20010093

Weak lensing observations of the "dark"cluster MG 2016+112

D. Clowe1, 2, N. Trentham3 and J. Tonry4

1  Max-Planck-Institut für Astrophysik, Karl Schwarzschild Str. 1, 85740 Garching, Germany
2  Currently at: Institut für Astrophysik und Extraterrestrische Forschung, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
3  Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
4  Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA

(Received 18 January 2000 / Accepted 9 January 2001 )

We investigate the possible existence of a high-redshift (z=1) cluster of galaxies associated with the QSO lens system MG 2016+112. From an ultra-deep R- and less deep V- and I-band Keck images and a K-band mosaic from UKIRT, we detect ten galaxies with colors consistent with the lensing galaxy within 225h-1 kpc of the z=1.01 lensing galaxy. This represents an overdensity of more than ten times the number density of galaxies with similar colors in the rest of the image. We also find a group of seven much fainter objects closely packed in a group only 27h-1 kpc north-west of the lensing galaxy. We perform a weak lensing analysis on faint galaxies in the R-band image and detect a mass peak of a size similar to the mass inferred from X-ray observations of the field, but located 64$\arcsec$ northwest of the lensing galaxy. From the weak lensing data we rule out a similar sized mass peak centered on the lensing galaxy at the $2\sigma$ level.

Key words: galaxies: clusters: individual: MG 2016+112 -- galaxies: clusters: individual: AX J2019+112 -- dark matter -- gravitational lensing

Offprint request: D. Clowe, clowe@astro.uni-bonn.de

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