Antipodal microwave

Abstract

view Abstract Citations (15) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Antipodal Microwave Durrer, Ruth ; Kovner, Israel Abstract We examine inflectional Friedmann-Lemaitre universes and find that current observations (gravitational lenses and QSO absorption lines) cannot rule out an antipode at z_a_ > 5. For z_a_ >> 1, the structure on the recombination shell is magnified, and the linear size observed at a given angular scale is much smaller than in an Einstein-de Sitter universe. In the extreme case of an antipode near or inside the shell, | z_a_ - z_r_ | <~ {DELTA}z_r_ the (linear) magnification is M_a_ 800{OMEGA}^1/2^_m0_; thus δT/T is reduced by photon diffusion and projection effects on scales <~90^deg^ (rather than <~ 8' in an Einstein-de Sitter universe). If 250 < z_a_ < infinity, we observe the microwave background radiation (MBR) emitted within a causally connected region; thus anisotropies from the Sachs-Wolfe effect are reduced. A high-redshift antipode produces anomalous ratios between the coefficients of the Taylor expansion of the MBR autocorrelation function. It can thus be ruled out or discovered when two or more such coefficients are measured. A simple test is the decrease of multibeam anisotropy measurements with the number of beams, on angular scales within some range above 8' x {OMEGA}^-1/2^_M0_ (in contrast to predictions of various theories in a flat universe). In addition, gravitational lensing by galaxies and clusters reduces MBR brightness contrasts on scales <~ 1'-1^deg^. To our knowledge, this effect has not been correctly appreciated before. We point out that it is analogous to the reflection of the Sun in an undulating water surface. However, on these scales, the antipodal magnification and the damping already reduce δT/T below the present-day sensitivity. Thus lensing by galaxies and clusters is irrelevant for current bounds on the MBR anisotropy (as it is in conventional cosmologies). An antipode at z_a_ 5-10 may produce a departure of the MBR from the blackbody spectrum, if it lies inside an infrared source. An obvious prediction, then, is large dipole and higher multipole moments of the departure, with axes uncorrelated with the known MBR dipole. Publication: The Astrophysical Journal Pub Date: June 1990 DOI: 10.1086/168814 Bibcode: 1990ApJ...356...49D Keywords: Antipodes; Cosmology; Gravitational Lenses; Quasars; Relic Radiation; Absorption Spectra; Black Body Radiation; Brightness Distribution; Computational Astrophysics; Galactic Clusters; Red Shift; Astrophysics; COSMIC BACKGROUND RADIATION; COSMOLOGY; GRAVITATIONAL LENSES full text sources ADS |