THE GREAT WALL IN THE CFA SURVEY - ITS ORIGIN AND IMPRINT ON THE MICROWAVE BACKGROUND-RADIATION

The Great Wall (GW) found in the latest CfA survey has clearly started out as an aspherical overdense region. We model its evolution after recombination and the imprint its time-dependent gravitational potential leaves in the microwave background radiation (MBR). We show that within the framework of the Zel'dovich approximation the (pre)GW region can be treated as ellipsoid. Consequently we approximate the GW as an oblate ellipsoid that started at recombination with an almost spherical shape, but with initial density contrast, delta(i), much smaller than it had to be in the spherical model in order to reach the observed density contrast of delta(f) approximately 5. The resultant delta(i) is compatible with the rms value of delta-rho/rho on the GW scale at recombination for models with the n < 0 power spectrum of the primordial density field. We show that the time-dependent potential of the GW will induce a detectable fluctuation in MBR. The amplitude of the resultant DELTA-T/T would depend on OMEGA and the overall density contrast of the mass distribution (or bias parameter), and therefore, MBR observations in that direction can further constrain these parameters. We also discuss the possibility of similar structures located at higher redshifts producing measurable and perhaps dominant statistical MBR anisotropies by this effect.