Telescope to Shed Light on Dark Matter

Scoping the heavens. A new 8-meter telescope will be built on this South Pole site.

Cosmologists will soon have the chance to study the sky with new eyes. On 15 August, the National Science Board, the governing body of the U.S. National Science Foundation (NSF), agreed to fund a $17 million microwave telescope at the South Pole. The as-yet-unnamed telescope, which will be up and running in roughly 4 years, offers a novel approach to mapping the distribution of matter in the universe.

The telescope will make use of the Sunyaev-Zel'dovich (SZ) effect, named after Russian physicists Rashid Sunyaev and Yakov Zel'dovich. The SZ effect is a distortion in the energies of photons left over from the early ages of the universe and occurs when those photons bump into hot electrons in galaxy clusters. Submillimeter-wavelength telescopes can detect the telltale distortion of the SZ effect, helping cosmologists find galaxy clusters too distant or dim to be spotted by other means. Those observations, in turn, can help cosmologists figure out how the clusters evolved--and possibly the location of dark matter in the universe.

The new 8-meter telescope will focus light from the sky on an array of sensitive heat-sensors called bolometers. Commonly, just a few bolometers scan the same patch of sky; having an array allows the telescope to map large areas of the sky at one time. "It will do several square degrees per day and hundreds of square degrees per year, depending on the weather," says Antony Stark of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, one of the co-investigators of the telescope project. "You will be able to see all significant clusters of galaxies in that area."

"We're really delighted" that the telescope has been approved, says John Carlstrom, an astronomer at the University of Chicago and principal investigator of the project. So are other cosmologists. "In 5 years, we'll have a much better understanding about the physics of the evolution of clusters," says August Evrard, a cosmologist at the University of Michigan, Ann Arbor, who says that galaxy clusters, along with supernova data and cosmic microwave background measurements, form a triad of crucial observations for cosmology.

Related sites
Office of Polar Programs
National Science Board

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