Issue |
A&A
Volume 386, Number 1, April IV 2002
|
|
---|---|---|
Page(s) | 12 - 30 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20020226 | |
Published online | 15 April 2002 |
Lens magnification by CL0024+1654 in the
and
band
1
Astrophysics Group, Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BW, UK
2
Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
3
Astronomical Observatory, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
4
Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
5
NORDITA, Blegdamsvej 17, 2100 Copenhagen Ø, Denmark
6
Science Institute, Dunhaga 3, 107 Reykjavik, Iceland
Corresponding author: S. Dye, sdye01@ic.ac.uk
Received:
28
August
2001
Accepted:
8
February
2002
We estimate the total mass distribution of the galaxy
cluster CL0024+1654 from the measured source depletion due to lens
magnification in the R band. Within a radius of , a
total projected mass of
(EdS) is measured. The
error here includes shot
noise, source clustering, uncertainty in background count
normalisation and contamination from cluster and foreground
galaxies. This corresponds to a mass-to-light ratio of
. We compute the luminosity function of CL0024+1654
in order to estimate contamination of the background source counts
from cluster galaxies. Three different magnification-based
reconstruction methods are employed: 1) an estimator method using a
local calculation of lens shear; 2) a non-local, self-consistent
method applicable to axi-symmetric mass distributions; 3) a non-local,
self-consistent method for derivation of 2D mass maps. We have
modified the standard single power-law slope number count theory to
incorporate a break and applied this to our observations. Fitting
analytical magnification profiles of different cluster models to the
observed number counts, we find that CL0024+1654 is best described
either by a NFW model with scale radius
and
normalisation
or a power-law profile with slope
, central surface mass density
and assuming a core radius of
. The NFW model
predicts that the cumulative projected mass contained within a radius R scales as
. Finally, we have exploited the fact
that flux magnification effectively enables us to probe deeper than
the physical limiting magnitude of our observations in searching for a
change of slope in the U band number counts. We rule out both a total
flattening of the counts with a break up to
and
a change of slope, reported by some studies, from
up to
with 95%
confidence.
Key words: gravitational lensing / galaxies: clusters: individual: CL0024+1654 / cosmology: dark matter
© ESO, 2002
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