By comparing infrared and X-ray background signals across the same stretch of sky, an international team of astronomers has discovered evidence of a significant number of black holes that accompanied the first stars in the universe.
Using data from NASA’s Chandra X-ray Observatory and NASA’s Spitzer Space Telescope, which observes in the infrared, researchers have concluded one of every five sources contributing to the infrared signal is a black hole.
"Our results indicate black holes are responsible for at least 20 percent of the cosmic infrared background, which indicates intense activity from black holes feeding on gas during the epoch of the first stars," said Alexander Kashlinsky, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md.
The cosmic infrared background (CIB) is the collective light from an epoch when structure first emerged in the universe. Astronomers think it arose from clusters of massive suns in the universe’s first stellar generations, as well as black holes, which produce vast amounts of energy as they accumulate gas.
Even the most powerful telescopes cannot see the most distant stars and black holes as individual sources. But their combined glow, traveling across billions of light-years, allows astronomers to begin deciphering the relative contributions of the first generation of stars and black holes in the young cosmos. This was at a time when dwarf galaxies assembled, merged and grew into majestic objects like our own Milky Way galaxy.
"We wanted to understand the nature of the sources in this era in more detail, so I suggested examining Chandra data to explore the possibility of X-ray emission associated with the lumpy glow of the CIB," said Guenther Hasinger, director of the Institute for Astronomy at the University of Hawaii in Honolulu, and a member of the study team.
Hasinger discussed the findings Tuesday at the 222nd meeting of the American Astronomical Society in Indianapolis. A paper describing the study was published in the May 20 issue of The Astrophysical Journal.