Researchers from NASA's Goddard Space Flight Center in Maryland believe they have captured traces of radiation from long-extinguished stars that were "born" during the universe's infancy.
The research represents the first tangible - but not conclusive - evidence of these earliest stars, which are thought to have produced the raw materials from which future stars, including our sun, were created.
The Big Bang, the explosion believed to have created the universe, is thought to have occurred 13.7 billion years ago. About 100 million years later, hydrogen atoms began to merge and ignite, creating brightly burning stars. Just what these stars were like wasn't clear.
Kashlinsky's team used NASA's Spitzer Space Telescope to measure the cosmic radiation, which is infrared light invisible to the human eye, in a small sliver of the sky. The team then subtracted the radiation levels of all known galaxies and suggested that the leftover measurements include radiation given off by those earliest stars.
If the team's conclusions are correct, the study will advance understanding of how the universe originally lit up.
Avi Loeb, a Harvard astronomy professor who was not involved in the research, said the early universe was probably dark for half a million years. Later, hydrogen coalesced into brightly burning stars that were hundreds to a million times more massive than the sun, and these are the stars whose fingerprints Kashlinsky's team hopes it has found.
Ned Wright, an astronomy professor at UCLA, was more doubtful. He argued that the process of removing the radiation contribution of other stars is too imprecise to make the team's conclusions valid.
"I'm very skeptical of this result. I think it's wrong," he said. "I think what they're seeing is incompletely subtracted residuals from nearby sources," Reuters quoted Wright as saying.
The strike was defensive in nature and came in response to three attacks on the US military in February