Collaborative Project: A Precision Measurement of the Polarization of the 2.7 K Cosmic Microwave Background Radiation

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AST-9813920 John Ruhl Dr. Ruhl and Dr. Timbie are collaborating on a two-phase program to measure the cosmic microwave background (CMB), first at large angular scales and later at small scales. This program operates in a single millimeter frequency band (26-36 GHz). .Recent measurements of the spectrum and the spatial anisotropy of the 2.7K CMB have dramatically improved our understanding of the early universe. The third characteristic of this radiation, its polarization, has not yet been detected. The amplitude of the linear polarization and its spatial distribution are extremely sensitive to both the source of the temperature anisotropy (density perturbations or gravitational waves) and the ionization history of the universe. The predicted polarization amplitude is less than or equal to 10% of the size of the COBE (Cosmic Microwave Background Explorer) anisotropy signals at 7o. The research team is using new receiver technology with 100 times more sensitivity than previous polarization experiments, as well as a novel instrument design. Detection of polarization will help to: provide details about the formation of structure in the universe; complement CMB temperature anisotropy measurements of cosmological parameters; determine if recombination was instantaneous; determine the redshift of reionization; distinguish between inflation and defect models for structure formation; probe magnetic fields in the early universe and in clusters of galaxies; understand galactic and extragalactic sources of polarized radiation. ***