In a new discovery related to the origins of the universe, scientists now say ancient black holes heated the gas in space later than previously thought.

Scientists at Tel Aviv University said in a press release that black holes from the universe's first stars also left radio waves signatures in space that can be detected today. Published in the journal Nature, scientists from Columbia University and Harvard College assisted in the research.

"One of the exciting frontiers in astronomy is the era of the formation of the first stars," study co-author Rennan Barkana, of the Tel Aviv School of Physics and Astronomy, said in the release. "Since the universe was filled with hydrogen atoms at that time, the most promising method for observing the epoch of the first stars is by measuring the emission of hydrogen using radio waves."

Astronomers can see the history of the universe looking out far enough into space's endless reaches. Since light can take years to reach the sight of Earth, astronomers simply have to expand their view far enough to see such ancient light. If the gas of the universe was warmed up at a later date, then astronomers no longer have search as deep in space anymore.

Several radio telescopes were designed and built with the assumption that these radio waves signatures would be too distant to see. The study would also imply these radio telescopes can detect ancient cosmic heating from the earliest black holes.

Cosmic heating is believed to be driven by explosions in pairs of stars. When the larger one exploded, it would have created a supernova that left a black hole in its place. Gas from the smaller star is pulled toward the black hole, ripped apart by gravity and re-emitted as far-reaching X-ray radiation.

"It was previously believed that the heating occurred very early," said Barkana, "but we discovered that this standard picture delicately depends on the precise energy with which the X-rays come out. Taking into account up-to-date observations of nearby black-hole binaries changes the expectations for the history of cosmic heating. It results in a new prediction of an early time (when the universe was only 400 million years old) at which the sky was uniformly filled with radio waves emitted by the hydrogen gas."