On the microwave background anisotropy produced by Great Attractor-like structures

Abstract

We model the effect on the cosmic microwave background of Great Attractor-like structures located at various distances from us. These structures are described by using the Tolman-Bondi solution of the Einstein equations. Two values of the density parameter, Omega <SUB>0</SUB> = 0.2 and Omega<SUB>0</SUB> = 1, are considered. Physical initial profiles of the energy density and the peculiar velocity lead to both compensated and uncompensated models. Nonlinear gauge-invariant computations give the angular distribution of the microwave background temperature. Angular sizes, amplitudes, and angular temperature profiles of various separable contributions to the total anisotropy are estimated and compared among them. These contributions are produced by the gravitational field, the peculiar velocities of the observer and the emitter, and the temperature fluctuations of the last scattering surface induced by Great Attractor-like structures. Compatibility with observational evidence is analyzed. It is proved that the greatest anisotropies are produced by Great Attractor-like objects located near the last scattering surface. Suitable angular scales for the future detection of these anisotropies are proposed. For fixed proportions of baryon and dark matter, results strongly depend on the value of the density parameter Omega<SUB>0</SUB>; the smallest anisotropies correspond to Omega<SUB>0</SUB> = 1.