When you hear the name Fermi National Accelerator Laboratory, or Fermilab for short, cosmology likely isn’t the first thing to cross your mind. But Fermilab researchers are busy building an astronomical camera that could help confirm that dark energy rules the current universe — or the unsettling alternative that scientists don’t understand gravity very well.
In 1998, cosmologists first learned that gravity’s influence has been dwindling ever since the Big Bang. Early in cosmic history, gravity’s attractive force slowed down the universe’s expansion. But roughly 5 billion years ago, the expansion rate started to speed up. The current best guess: A mysterious anti-gravity force, dubbed “dark energy,” has taken over. Scientists think dark energy now constitutes nearly three-quarters of the mass and energy in the universe.
But being scientists, they want to know for sure. Enter the DES. This survey will measure some 300 million galaxies out to a distance of about 9 billion light-years. It will study dark energy using four methods: the abundance of massive galaxy clusters, the gravitational lensing of light by galaxies and clusters, the large-scale clustering of galaxies, and the brightnesses of distant supernovae.
To accomplish the survey, Fermilab scientists will attach the Dark Energy Camera to the 4-meter Blanco Telescope at Cerro Tololo, Chile. The 4-meter scope offers a perfect combination of a wide field of view and the ability to go deep. The 570-megapixel camera contains 74 CCD chips, and a single image captures an area of sky 20 times the size of a Full Moon. The camera will operate 105 nights per year starting in September 2011, and continue for 5 years.
Related blog:Road trip: Fermi National Accelerator Laboratory, by Liz Kruesi, associate editor