CARA Science:
Cosmic Microwave Background Radiation Research


The Cosmic Microwave Background (CMB) has a wealth of information about the origin and evolution of the Universe in its signal. Its spectrum is that of a blackbody at 2.7 K, confirmation of the prediction made by the standard Big Bang model. Its angular power spectrum contains information on the structure that existed at decoupling. Anisotropy in the matter distribution at this time left imprinted upon the CMB a small anisotropy (deltaT/T ~10^-5) in the angular distribution of microwave power. The amplitude and spatial distribution of the anisotropy are directly related to the conditions in the early Universe which gave rise to the onset of structure formation. All current models of structure formation predict specific power spectra and morphologies for the CMB anisotropy. Within the context of a given theory, the cosmological parameters such as the Hubble constant H0, and the mass density of the Universe omega = rho/rhoc, can be estimated from observations of the anisotropy in the CMB. Determining the angular power spectrum of the fluctuations, their distribution function, and imaging the CMB anisotropy at intermediate angular scales (20 arcseconds to 1 degree) is the scientific goal of the CARA CMB program.

Measuring the angular power spectrum of the CMB fluctuations, and producing images of the primary and secondary anisotropy of the CMB, are key science goals of CARA experiments. Each experiment addresses a unique range of angular scales and frequency coverage. Together, they span a range of angular scales from 3 degrees to 2 arcminutes, and frequencies from 26 - 400 GHz.

CARA CMB instruments include:

Site characterization information.