Journal article

Hubble space telescope observations of BL Lacertae environments

JE Pesce, CM Urry, M O'Dowd, R Scarpa, R Falomo, A Treves

NEW ASTRONOMY REVIEWS | ELSEVIER SCI LTD | Published : 2002

Abstract

We analyze images of BL Lacertae objects obtained with the Hubble Space Telescope WFPC2 and the F814W filter. The nine objects cover a redshift range of 0.19 to 0.997. The relatively deep images are sufficient to detect galaxies at least one magnitude below MI* ( 21.4) and in most cases to three magnitudes below M*. Galaxy enhancement over the average background is found around four out of the nine objects. Results for some cases are confirmed by ground-based imaging. In the other cases, the redshifts of the target BL Lac objects may be incorrect or they are truly isolated. These findings reinforce the idea that on average, BL Lac objects are found in regions of above average galaxy density...

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University of Melbourne Researchers