Overview of the Canadian hydrogen intensity mapping experiment (CHIME)

The Baryon Acoustic Oscillations (BAO) which occurred in the early universe have left a distinctive imprint in subsequent large-scale structure, thereby providing a standard, cosmological ruler. Measurements of the apparent diameter of BAO over an appreciable period of cosmic time thus reveal the expansion history of the universe and can provide valuable new data for constraining models of dark energy. Intensity mapping of hydrogen's 21 cm line over a broad range in frequencies is an exciting new prospect for determining the large scale, three-dimensional structure of the universe in pursuit of this goal.