CAN THE LACK OF SYMMETRY IN THE COBE DMR MAPS CONSTRAIN THE TOPOLOGY OF THE UNIVERSE

Although the cubic T-3 ''small universe'' has been ruled out by COBE D ifferential Microwave Radiometer (DMR) results as an interesting cosmo logical model, we still have the possibility of living in a universe w ith a more anisotropic topology, such as a rectangular T-3 ''small uni verse'' with one or two of its dimensions significantly smaller than t he present horizon (which we refer to as T-1 and T-2 models; respectiv ely). In order to rule out these anisotropic topologies as well, we ap ply a new data analysis method that searches for the specific kind of symmetries that these models should produce. We find that the 4 year C OBE DMR data place a lower limit on the smallest cell size for T-1 and T-2 models of 3000 h(-1) Mpc, at 95% confidence, for a scale-invarian t power spectrum (n = 1). These results imply that all toroidal univer ses (cubes and rectangles) are ruled out as interesting cosmological m odels.