Astrophysicists from McGill, UBC, UofT seek to probe mysteries of ‘dark energy’
By McGill Reporter Staff
A $4.6 million award from the Canadian Foundation for Innovation (CFI) will help astrophysicists at McGill, the University of British Columbia, the University of Toronto and the Dominion Radio Astrophysical Observatory build a novel digital radio telescope designed to map a larger volume of the universe than any previous telescope.
The collaborative project, known as the Canadian Hydrogen Intensity Mapping Experiment (CHIME), is designed to shed new light on the evolution of the universe by studying the mysterious “dark energy” that is thought to account for the universe’s accelerating expansion. The award – provided through CFI’s Leading Edge Fund – brings total funding for CHIME to $11 million, including $1.6 million from Quebec’s Ministère de l’Enseignement supérieur, de la Recherche, de la Science et de la Technologie.
CHIME will be built at the National Research Council’s radio observatory in Penticton, BC, which is legally protected from radio interference and is one of the best sites in the world for this research. The project exploits a new technique called hydrogen intensity mapping, pioneered by a team led by UofT’s Ue-Li Pen, which enables a radio telescope to survey huge volumes for a fraction of the cost of other methods. The CHIME observatory, which has no moving parts and scans half of the sky every day, will produce the largest-volume survey of cosmic structure ever measured, the researchers say.
“An enormous advantage of a digital telescope is that it does not need to be physically steered towards a particular source in the sky”, explains McGill astrophysicist Matt Dobbs. “This is done digitally, so there are no moving parts required for the telescope itself. With digital signal processing we can achieve the very high sensitivity and stability we need to find the cosmological signal.
“The signal we are looking for is very weak, and we expect it will take us at least two years to detect it,” Dobbs adds.
For most of the 20th century, physicists supposed that the mutual gravitational pull of galaxies on each other would cause the rate of expansion of the universe to continually slow down as it aged, notes UBC’s Kris Sigurdson. The discovery at the end of the century that the universe’s expansion is actually speeding up left cosmologists grappling for an explanation.
“Accelerated expansion implies either that the universe is filled with a gravitationally repulsive ‘dark energy’, or that Einstein’s general relativity is somehow wrong,” notes UofT’s Dick Bond. “Understanding the origin of cosmic acceleration is now one of the highest priorities in the physical sciences, and is CHIME’s main goal.”
CFI, through its competitive review process, “has given us the mandate to pioneer the use of digital telescopes for cosmology and the chance to bring this technology to bear on a profound new cosmic mystery”, says McGill physicist David Hanna.
Construction of a CHIME pathfinder instrument, 10% of the final size, has begun already. Its purpose is to refine mechanical and electronic design for the full telescope, whose construction will begin in mid-2014.
The CFI grant for CHIME was part of $215 million in funding, announced Jan. 16, for cutting-edge research infrastructure across Canada. That announcement also included $10.9 million for three McGill-led projects involving structural biology, nanoelectronics, and nanomedicine.