Faint distorted structures in the core of A 370: are they gravitationally lensed galaxies at redshift z of about 1?

This letter presents an analysis of deep and high resolution CCD images of the field of the cluster of galaxies Abel 370 (z=0.374). The giant arc near the center was recently identified as the image of a distant galaxy that was gravitationally lensed by the cluster core. No counter arc is found where expected, but several faint and elongated objects are detected in the field. By far bluer than all cluster members, these structures are probably gravitationally lensed, distorted and amplified background galaxies at redshift z of about 1. This reinforces the hypothesis that both dark and visible matter are essentially concentrated in the core of clustes of galaxies and act as gravitational lenses. From this observation, we predict that many such very distant and early galaxies may be detected in the near future from deep photometry of the cores of centrally concentrated clusters at intermediate redshift (z about 0.5)