"The question has been staring us in the face for 40 years," says Pierre Sokolsky, a University of Utah distinguished professor of physics and astronomy and principal investigator on the Telescope Array's current National Science Foundation grant.
"We know these particles exist, we know that they are coming from outside our galaxy and we really don't have a clue as to how nature pumps that much energy into them," Sokolsky
outlined these details of the Telescope Array expansion, which team members refer to as "TAx4" for the near-quadrupling of the area covered "Japan, which paid for about two-thirds of the existing $25 million observatory, will spend another 450 million yen (currently $3.6 million) to expand the existing array of table-like scintillation detectors that measure "air shower" particles produced when incoming cosmic rays hit nitrogen and other gases in the atmosphere.
Japan's funding is approved and a decision on the University of Utah's
grant request is expected early in 2016, Sokolsky
says the researchers also must gain approval to expand onto more public lands owned by the U.S. Bureau of Land Management and Utah's
School and Institutional Trust Lands Administration.
The existing observatory sits mostly on land owned by those two agencies and on some private land.
Expansion will delve into cosmic ray hotspot
Discovery of the hotspot was the impetus for the planned expansion, Sokolsky
The discovery was announced by an international team of 125 scientists - including 32 from the University of Utah
- in July 2014 when their findings were accepted for publication in Astrophysical Journal Letters.
The hotspot's existence "is at the statistical level where it could go either way," Sokolsky
says, adding that without the expansion, "we won't know if it's real unless you want to stick around for 40 years."
"We see this intriguing clustering of the highest-energy cosmic rays coming from one area of the sky," he
says the visitors included about 20 researchers from Japan and several more from Russia and Belgium.