Cosmological Changes in Fundamental Constants of Nature

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

AST-0707480 Stocke This is a project to measure the change in certain fundamental "constants" of nature over cosmic time, using molecular absorption lines in the spectra of very distant sources. Determining whether fundamental constants vary is a frontier study both in modern cosmology and in particle physics. The aim is both to increase the sensitivity of such measurements by a factor of three to five, and to increase the range of cosmic times over which determinations can be made. This involves a search for new, highly-redshifted molecular absorbers, and their use to determine, or set limits on, the rate of change of the fine structure constant, the proton gyromagnetic ratio, and the ratio of proton mass to electron mass. The methodology, focusing on the use of the "conjugate" lines of the OH molecule, offers significant advantages compared to other approaches, such as more accurate frequency calibration and minimizing systematic errors due to relative gas motion of different species. As well as considering secular changes in physical constants, this work will measure the molecular gas mass as a function of redshift, make in-situ measurements of the Cosmic Microwave Background temperature, find new examples of compact symmetric radio galaxies, test the radio-loud model for Active Galactic Nuclei, and determine the changing physical conditions in star-forming molecular clouds over cosmic time. In addition to training a new generation of radio astronomers in observing techniques at both the high- and low-frequency ends of the radio spectrum, this study includes developing a planetarium talk, an undergraduate introductory module, and an Aspen workshop, on the implications of the research.