Morphology of High Redshift 3CR Galaxies (Z>1), from High Spatial Resolution Imaging

Extract

This sample is a small one, typically 20 galaxies with z > 1, is radio flux limited and contains the most distant galaxies we presently know. Gravitational lensing by foreground galaxies and clusters of galaxies may enhance the luminosity of these galaxies by several magnitudes in both optical and radio wavelenghts. Moreover this flux limited sample should have a disproportionate number of gravitationaly amplified objects specifically because their radio fluxes are very close to the 10 Jy detection limit. When considering the spatial distribution of the 3CR galaxies with z > 1 it is found that many cases exist in which a 3CR galaxy is located near the center of a rich cluster of galaxies and/or with a foreground galaxy projected within a few arcseconds. These instances are strongly suggestive that gravitational lensing effects are likely to be present (see Hammer et al., 1986, Astr. Astroph., 169, LI, Le Fèvre et al., 1987, Nature, 326, 268). Moreover, it is not well established that these galaxies are the progenitors of lower redshift ellipticals and radio-galaxies and that they can be compared for galaxy evolution tests.