The Great Wall in the CfA Survey: Its Origin and Imprint on the Microwave Background Radiation
Abstract
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 timedependent 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, δ_i_ much smaller than it had to be in the spherical model in order to reach the observed density contrast of δ_f_ ~ 5. The resultant δ_i_ is compatible with the rms value of δρ/ρ on the GW scale at recombination for models with the n < 0 power spectrum of the primordial density field. We show that the timedependent 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.
 Publication:

The Astrophysical Journal
 Pub Date:
 May 1992
 DOI:
 10.1086/171282
 Bibcode:
 1992ApJ...390..322A
 Keywords:

 Background Radiation;
 Cosmology;
 Galactic Evolution;
 Gravitation;
 Microwaves;
 Universe;
 Astronomical Models;
 Red Shift;
 Temperature Distribution;
 Astrophysics;
 COSMOLOGY: COSMIC MICROWAVE BACKGROUND;
 COSMOLOGY: LARGESCALE STRUCTURE OF UNIVERSE;
 GALAXIES: FORMATION;
 GRAVITATION