A search for anisotropy in the cosmic microwave background on angular scales of 1 to 30 arcminutes

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5702909

Myers, S T

Observations at a frequency of 20 GHz from the Owens Valley Radio Observatory with the 40 meter diameter radiotelescope are used to place limits on the anisotropy of the cosmic microwave background radiation, believed to be a relic from the Big Bang. Two experiments, designated NCP and RING, were performed with the former consisting of deep measurements in 8 fields at the declination delta = 89 degrees and the later a survey of 96 fields at declination delta = 88 deg 10 min 42 sec. Bayesian statistical analysis of the 8 NCP field observations place a 95 percent confidence upper limit of delta T/T is less than 1.9 x 10(exp -5) and 4.2 x 10(exp -5) for 99.87 percent confidence (3 sigma) on the amplitude of fluctuations. The 96 fields of the RING experiment were observed in an interlocked ring-like geometry to enhance the sensitivity of the experiment to larger-scale anisotropies. Because of the larger area of sky covered, this data was more susceptible to contamination by discrete extragalactic radio sources and separate lower frequency observations were used to identify and correct for the contribution of these objects. The statistical analysis of the RING data results in the limits on the anisotropy of 2.5 is less than delta T/T is less than 5.0 x 10(exp -5) (95 percent) and 1.9 is less than delta T/T is less than 6.1 x 10(exp -5) (99.87 percent) for fluctuations with a correlation angle of 2.6 min. Because of the high probability of residual source contamination, these results are treated as upper limits on intrinsic background fluctuations. These experiments constrain the amplitude to be less than 3 x 10(exp -4) for correlation angles between 0.1 and 30 min (95 percent). The implications for cosmology and theories of galaxy formation are discussed, and models without significant non-baryonic matter and/or non-standard recombination are excluded by the observations.

• Research Organization: California Inst. of Tech., Pasadena, CA (USA)
• OSTI ID: 5702909
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANISOTROPY
BACKGROUND RADIATION
COSMIC RADIATION
DATA
EXPERIMENTAL DATA
GALACTIC EVOLUTION
INFORMATION
IONIZING RADIATIONS
MICROWAVE SPECTRA
NUMERICAL DATA
RADIATIONS
SPECTRA