First cosmic objects
burned brightly, astronomers say
A faint, lumpy glow from the first objects in the universe may have been detected with the best precision yet, using NASA's Spitzer Space Telescope, astronomers say.
The objects might be enormous stars or voracious black holes, the scientists add; they're too distant to make out individually, but Spitzer has captured evidence of what seems to be an overall pattern created by their light. The observations help confirm the first objects were numerous and burned furiously, astronomers claim.
"These objects would have been tremendously bright," said Alexander "Sasha" Kashlinsky of NASA's Goddard Space Flight Center in Greenbelt, Md., lead author of a paper on the findings published in The Astrophysical Journal. "We can't yet directly rule out mysterious sources for this light that could be coming from our nearby universe, but it is now becoming increasingly likely that we are catching a glimpse of an ancient epoch. Spitzer is laying down a roadmap for NASA's upcoming James Webb Telescope, which will tell us exactly what and where these first objects were."
The Spitzer telescope first caught hints of the remote pattern of light, known as the cosmic infrared background, in 2005, and again with more precision in 2007. Now, Spitzer is in an extended phase of its mission, during which it performs more in-depth studies on specific patches of the sky. Kashlinsky and his colleagues used Spitzer to look at two patches of sky for more than 400 hours each.
The team then subtracted all the known stars and galaxies in the images. Rather than being left with a black, empty patch of sky, they found faint patterns of light with several telltale characteristics of the cosmic infrared background. The lumps in the pattern are consistent with the way the very distant objects are thought to be clustered together, the researchers said.
Kashlinsky likens the observations to looking for fireworks in New York city from Los Angeles. First, you'd have to remove all the foreground lights between the two cities, as well as the blazing lights of New York itself. You ultimately would be left with a fuzzy map of how the fireworks are distributed, but they would still be too distant to make out individually.
"We can gather clues from the light of the universe's first fireworks," said Kashlinsky. "This is teaching us that the sources, or the "sparks," are intensely burning their nuclear fuel."
The universe is thought to have formed some 13.7 billion years ago in a fiery, explosive event called the Big Bang. With time, it cooled and, by around 500 million years later, the first stars, galaxies and black holes began to take shape. Astronomers say some of that "first light" might have traveled billions of years to reach the Spitzer Space Telescope. The light now appears as infrared---a low-energy form of light invisible to the unaided eye---because the universe has been expanding, a process that stretches out light waves, turning them into infrared.
The new study was designed to improve on previous observations by measuring this cosmic infrared background out to scales equivalent to two full moons---a good deal larger than what was detected before. Imagine trying to find a pattern in the noise in an old-fashioned television set by looking at just a small piece of the screen. It would be hard to know for certain if a suspected pattern was real. By seeing a larger section of the screen, you could resolve small- and large-scale patterns, further confirming your initial suspicion.
Likewise, astronomers using Spitzer have increased the amount of sky examined to obtain more definitive evidence of the cosmic infrared background. The researchers plan to explore more patches of sky in the future to gather more clues hidden in the light of that ancient time:
Courtesy of NASA Jet Propulsion Laboratory and World Science staff