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Astron. Astrophys. 321, L1-L4 (1997)

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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 Fsica Moderna, UC, Fac. de Ciencias, Avda. Los Castros s/n, E-39005 Santander, Spain

Received 28 February 1997 / Accepted 11 March 1997


[FORMULA] band imaging of a sample of 21 radiogalaxies with [FORMULA] 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]). 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] 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

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998