The world's most sensitive digital camera has begun peering into deep space, and the barred spiral galaxy NGC 1365 looks to be staring right back. Some 60 million light-years from Earth, NGC 1365 stars among the first pictures from the new 570-megapixel Dark Energy Camera, released Tuesday.
Built at the U.S. Department of Energy's Fermi National Accelerator Laboratory in Illinois, the extremely sensitive camera is now perched atop a Chilean mountain—the better to absorb the faint light of galaxies as far as eight billion light-years away.
Beautiful as the new pictures may be, the real work begins in December with the kickoff of the largest galaxy survey yet, which scientists hope will shed light on one of astronomy's biggest puzzles.
"The expansion of the universe is speeding up, and that's one of the great mysteries of science, because gravity pulls things together and should be slowing this down," said Dark Energy Survey director Josh Frieman. "So there must be something else pushing it apart. Dark energy is a name for this phenomenon that we don't understand."
The silver-domed Victor Blanco Four-Meter Telescope at the National Science Foundation's Cerro Tololo Inter-American Observatory (CTIO) in Chile is home to the Dark Energy Camera.
A few cameras on other telescopes boast more megapixels, but the Dark Energy Camera has an extremely wide field of view, which enables the machine to cover more sky, said Frieman, an astronomer with the University of Chicago.
"Our plan is to use it to survey about one-eighth of the entire sky and measure 300 million galaxies and 4,000 supernovae over the next five years," Frieman explained.
The camera is also especially sensitive to very red light. That's useful because the expansion of the universe stretches light from very distant sources in such away that it appears red—a phenomenon known as redshift. (Dark energy fast facts: why the universe is expanding.)
Photograph courtesy NOAO/NSF
Proof of Concept
In an undated picture scientists build a prototype of the Dark Energy Camera, which is now operational and achieved first light on September 12.
Dark energy is an unexplained, gravity-repelling force that appears to make up 75 percent of the universe's total mass. The force had no name until the 1990s and still can't be observed directly or even explained plausibly. But its observable impact on the universe's expansion likely means that it's either an exotic state of matter that exerts a gravitational force opposite to that of known matter—or that the laws of physics may need a rewrite.
The Dark Energy Survey will use the new camera's 62 tile-like image sensors to quantify the two main effects of dark energy in the sky.
The force "speeds up expansion of the universe," Frieman said, "so we can try to measure the history of the cosmic expansion much more precisely than ever before"—possible because light from, say, eight billion light-years away yields images of the universe as it existed eight billion years ago.
"And because [dark energy] competes with gravity, it affects how structures in the universe form," he said. Capturing the differing shapes of star clusters from ten billion years ago versus five billion years ago, for example, could facilitate the measurement of the effects of dark energy.
Photograph courtesy Reider Hahn, Fermilab
A mosaic of pictures—each "tile" from a single image sensor on the Dark Energy Camera—pieces together the center of a globular star cluster called 47 Tucanae, some 17,000 light-years from Earth. The crisp, clear atmospheric conditions of the Chilean Andes will be a boon to the camera's galaxy survey.
Image courtesy Dark Energy Survey Collaboration
Seen as a band of greenish stars, the Small Magellanic Cloud, a satellite of our own Milky Way galaxy, stretches across a Dark Energy Camera composite picture. In addition to probing its namesake mystery, the camera will be made available to scientists around the world exploring everything from local asteroids to the ultimate fate of the universe.