 |
 |
Astron. Astrophys. 339, L65-L68 (1998)
Letter to the Editor
Unveiling the nature of the Cloverleaf lens-system: HST/NICMOS-2 observations *
J.-P. Kneib 1,
D. Alloin 2 and
R. Pelló 1
1 Observatoire Midi-Pyrénées, CNRS-UMR5572,
14 Av. Edouard Belin, F-31400 Toulouse, France
2 CNRS-URA2052, Service d'Astrophysique, CE Saclay, l'Orme
des Merisiers, F-91191 Gif-sur -Yvette Cedex, France
Received 17 April 1998 / Accepted 18 October 1998
Abstract
We present new elements in the identification of the Cloverleaf
lens-system based on recent NICMOS-2/F160W observations. After a
careful PSF subtraction of the 4 images of the quasar, the residual
![[FORMULA]](img1.gif)
image reveals the presence of a faint object
(H![[FORMULA]](img2.gif)
20.5) amid the 4 quasars. This object
corresponds to a single galaxy that we identify as the primary lens of
the lens-system. From the R, I and H photometry of the galaxies
surrounding the Cloverleaf we also derive a photometric redshift. We
find that most of them are consistent with belonging to a galaxy
cluster/group with mean redshift ![[FORMULA]](img3.gif)
: they are
likely to be the other component in the lens-system that provides the
additional "external" shear. Furthermore, we detect 2 very red objects
(I-H4): the faintest one has no observed optical
(![[FORMULA]](img4.gif)
and ![[FORMULA]](img5.gif)
) counterpart, and the
brightest has a predicted redshift ![[FORMULA]](img6.gif)
, and may be
identified with one of the Cloverleaf absorbers. This
gravitational-lens system constitutes an excellent target for
imaging/spectroscopy with the new generation of 8m ground-based
telescopes.
Key words: gravitational
lensing 
clusters of
galaxies
gravitational lensing: Cloverleaf (H1413+117)
* Based on observations obtained with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under the NASA contract NAS 5-26555.
Send offprint requests to: D. Alloin (alloin@eso.org)
Contents
- 1. Introduction
- 2. The HST/NICMOS-2 data
- 3. The quadruple quasar and the primary galaxy-lens
- 4. Photometric redshifts of the faint objects surrounding the Cloverleaf
- 5. Discussion and concluding remarks
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998
Online publication: October 22, 1998
helpdesk.link@springer.de