Limits to global rotation and shear from the COBE DMR four-year sky maps
Abstract
Small departures from a homogeneous isotropic spacetime create observable features in the large-scale anisotropy of the cosmic microwave background. We cross correlate the maps of the cosmic microwave background anisotropy from the Cosmic Background Explorer Differential Microwave Radiometers four-year data set with template maps from Bianchi type VIIh cosmological models to limit global rotation or shear in the early universe. On the largest scales, spacetime is well described by the Friedmann-Robertson-Walker metric, with departures from isotropy about each spatial point limited to shear σ/H0<10-9 and rotation ω/H0<6×10-8 for 0.1<=Ω0<=1.
- Publication:
-
Physical Review D
- Pub Date:
- February 1997
- DOI:
- 10.1103/PhysRevD.55.1901
- arXiv:
- arXiv:astro-ph/9701090
- Bibcode:
- 1997PhRvD..55.1901K
- Keywords:
-
- 98.80.Es;
- 98.70.Vc;
- Observational cosmology;
- Background radiations;
- Astrophysics
- E-Print:
- 10 pages LaTeX including 3 PostScript figures using psfig style macro. To appear in Physical Review D15