Four-Year COBE DMR Cosmic Microwave Background Observations: Maps and Basic Results
Abstract
In this Letter we present a summary of the spatial properties of the cosmic microwave background radiation based on the full 4 yr of COBE Differential Microwave Radiometer (DMR) observations, with additional details in a set of companion Letters. The anisotropy is consistent with a scale-invariant power-law model and Gaussian statistics. With full use of the multifrequency 4 yr DMR data, including our estimate of the effects of Galactic emission, we find a power-law spectral index of n = 1.2 +/- 0.3 and a quadrupole normalization Qrms-PS = 15.3^{+3.8}_{-2.8} mu K. For n = 1 the best-fit normalization is Qrms-PS|n=1 = 18 +/- 1.6 mu K. These values are consistent with both our previous 1 yr and 2 yr results. The results include use of the l = 2 quadrupole term; exclusion of this term gives consistent results, but with larger uncertainties. The final DMR 4 yr sky maps, presented in this Letter, portray an accurate overall visual impression of the anisotropy since the signal-to-noise ratio is ~2 per 10 deg sky map patch. The improved signal-to-noise ratio of the 4 yr maps also allows for improvements in Galactic modeling and limits on non-Gaussian statistics.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1996
- DOI:
- arXiv:
- arXiv:astro-ph/9601067
- Bibcode:
- 1996ApJ...464L...1B
- Keywords:
-
- COSMOLOGY: COSMIC MICROWAVE BACKGROUND;
- COSMOLOGY: OBSERVATIONS;
- Astrophysics
- E-Print:
- 11 pages plus 2 PostScript figures. Figures 2 and 4 are not included, but are available upon request to bennett@stars.gsfc.nasa.gov. Submitted to The Astrophysical Journal (Letters)