Positive values of the cosmological constant, lambda, have been suggested to resolve a number of problems in observational cosmology, incuding the possible discrepancy between stellar ages and the inverse of Hubble's constant. In closed cosmological models with positive lambda, a distant source can produce a "ghost image," an image lying 180 degrees away from the source (Petrosian and Saltpeter, Ap. J., 1968). Previous searches (Solheim, Nature, 1968 and Biraud & Mavrides, A. & A., 1980) have failed to find such ghost images, but were compromised because they did not consider aberration produced by the motion of the earth. We have made a much more intensive search using the recently compiled NVSS catalog and a correction for aberration, and yet have found no evidence for ghost images. Our results constrain values of lambda, and some multiply connected models for the topology of the Universe.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1997