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Astron. Astrophys. 321, L1-L4 (1997)
Letter to the Editor
Statistical excess of foreground galaxies around high _z radiogalaxies *
N. Benítez 1, 2,
E. Martínez-González 1, and
J.M. Martín-Mirones 1, 2
1 IFCA, CSIC-UC, Fac. de Ciencias, Avda. Los Castros s/n,
E-39005 Santander, Spain
2 Dpto. de F
sica
Moderna, UC, Fac. de Ciencias, Avda. Los Castros s/n, E-39005
Santander, Spain
Received 28 February 1997 / Accepted 11 March 1997
Abstract
![[FORMULA]](img2.gif)
band imaging of a sample of 21 radiogalaxies
with ![[FORMULA]](img3.gif)
reveals the existence of a statistical
association of foreground galaxies with the positions of the
radiosources. The excess is detected within a 1' radius at a high
significance level (![[FORMULA]](img4.gif)
). K -band light is a
good tracer of stellar mass, so this result indicates the existence of
an association between foreground mass perturbations and background
radiosources, as expected from the magnification bias effect, and
confirms previous results obtained for other high
![[FORMULA]](img1.gif)
radio-loud AGN.
Key words: radiogalaxies 
gravitational
lensing
magnification bias
* Based on observations made with the 2.2m Telescope at Calar Alto
Send offprint requests to: N. Benítez
Contents
- 1. Introduction
- 2. Observations and data reduction
- 3. Statistical analysis and results
- 4. Discussion and conclusions
- Acknowledgements
- References
© European Southern Observatory (ESO) 1997
Online publication: June 30, 1998
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