QUIET observations of CMB polarization at 95 GHz

California Institute Of Technology, Pasadena CA

Investigators

Abstract

This research project will produce the most sensitive maps yet of Cosmic Microwave Background (CMB) polarization by extending observations with the Q and U Imaging ExperimenT (QUIET) through 2010. With prior NSF and other support, the QUIET collaboration has constructed and deployed two large receiver arrays of correlation polarimeters, one for 44 GHz (Q band) and one for 95 GHz (W band), and has completed a successful nine month campaign of Q band observations producing outstanding results. The project team are now observing with the W-band receiver, which is the largest, most sensitive polarimeter array of any experiment to date. Observations of the CMB, in particular the temperature anisotropies, are a cornerstone of precision cosmology, providing a wealth of information about the structure of the Universe and conditions at early times. CMB polarization observations add qualitatively distinct information, but only recently have reached the level of sensitivity to provide meaningful constraints on cosmological models. With more precise measurements of the angular power spectrum, QUIET will continue to test the standard cosmological model, further limiting proposed variants. This research will tighten the limits on CMB B-mode polarization signals generated either by foreground gravitational lensing or by primordial gravitational waves. These new deep observations will study polarized foregrounds, particularly synchrotron, at levels approaching those needed to extract cosmological information about primordial B-mode signals. In addition to their intrinsic interest, these foreground studies will enhance the interpretation of results from other contemporaneous CMB experiments and influence the design of future experiments. Cosmology continues to captivate the public imagination. QUIET will contribute to understanding by disseminating the results and their context to a broad range of audiences. This research collaboration continues a strong tradition of training students through research, providing both technical and collaborative experiences as a foundation for future achievements. Because the observations are from a Chilean site, there is a special interest in academic and scientific cooperation with institutions there. The outreach program allows Chilean school science classes to design and carry out their own radio astronomy observations. QUIET is a global collaboration, with strong ties among US universities, federal research centers, and institutions outside the US.