Probing Cosmology with Diffuse Background Radiation Observations

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The long--term objective of my research program is to understand the origin and evolution of the universe, and to shed light on the physics of dark matter and dark energy. In collaboration with a number of other astrophysics researchers, I design, build, and operate special purpose telescopes that collect radio and microwave signals from our own galaxy - the Milky Way - and from more distant sources, some as far away as the edge of the observable universe. The data we collect comprises a valuable fossil record of conditions in the younger universe, and help us tease out how the universe formed and evolved. Existing cosmological observations have pointed to the existence of dark matter: a form of matter which does not occupy the Periodic Table of the elements; and to dark energy, which could be energy associated with the vacuum of free space itself, as posited by quantum theory. The bulk of my proposed research effort is devoted to building and operating two new telescopes: the Canadian Hydrogen Intensity Mapping Experiment (CHIME), and the Canadian Galactic Emission Mapper (CGEM), both of which are or will be located at the Dominion Radio Astrophysical Observatory, located just south of Penticton British Columbia. CHIME is a novel and complex radio telescope comprised of 4 co-linear cylindrical reflectors with 2048 receiving elements. Its primary goal is to characterize dark energy by measuring the expansion history of the universe in the redshift range z=0.8-2.5, when the universe was roughly half its present age. CHIME recently detected cosmological 21 cm emission in cross correlation with data from the Sloan Digital Sky Survey, an important milestone in the path to characterizing the dark energy. Continuing the analysis of CHIME data is a major element of my proposed research. CGEM is to be a nimble 4-metre scanning telescope which will survey the northern sky at a frequency of ~10 GHz to map polarized synchrotron emission in the Milky Way. This signal is an important source of foreground confusion for cosmic microwave background (CMB) experiments that are searching for evidence of primordial gravitational waves produced a fraction of a second after the Big Bang, by a hypothesized period of cosmic inflation. If present, the gravity wave background would produce a curl-like pattern in the CMB polarization, but existing upper limits on such a signal already indicate that it will be foreground dominated at all frequencies, hence it is crucially important to have well-characterized foreground measurements over a range of frequencies spanning the CMB frequency "window" in order to disentangle the CMB and foreground signals. This pair of relatively small astrophysics projects are akin to "tabletop" experiments in laboratory physics. Designed and purpose built in-house, but with very high-profile science goals, they attract very talented HQP and serve as ideal training grounds for students seeking to become well-rounded scientists.