A new study reveals that black holes, formed from the first stars in our universe, heated the gas throughout space later than previously thought.
They also imprinted a clear signature in radio waves which astronomers can now search for. The work is a major new finding about the origins of the universe.
"One of the exciting frontiers in astronomy is the era of the formation of the first stars," Prof. Rennan Barkana of Tel Aviv University's School of Physics and Astronomy, an author of the study said.
"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," Barkana said.
Astronomers explore our distant past, billions of years back in time. Unlike Earth-bound archaeologists, however, who can only study remnants of the past, astronomers can see the past directly. The light from distant objects takes a long time to reach the Earth, and astronomers can see these objects as they were back when that light was emitted. This means that if astronomers look out far enough, they can see the first stars as they actually were in the early universe.
Thus, the new finding that cosmic heating occurred later than previously thought means that observers do not have to search as far, and it will be easier to see this cosmic milestone.
The study is published in the prestigious journal Nature.