Astronomers Spot Signal From Universe’s First Stars, Hint At Dark Matter’s Influence On Early Universe

The study suggests that dark matter might have caused hydrogen gas from the earliest stars to be much colder than once thought.

Astronomers Spot Signal From Universe's First Stars, Hint At Dark Matter's Influence On Early Universe
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The study suggests that dark matter might have caused hydrogen gas from the earliest stars to be much colder than once thought.

Astronomers have gotten a glimpse of the earliest days of the universe, picking up a signal from some of the first stars created after the Big Bang. The new findings could also point to dark matter having an influence on the early universe beyond its gravitational pull, and offer some insight on the substance believed to take up a huge bulk of the universe’s composition.

According to the Los Angeles Times, the new discovery could have some serious potential to answer questions about the infancy of our universe, and the oftentimes mysterious nature of dark matter. The earliest stars were formed about 100 million years or so after the universe formed via the Big Bang, and were generally blue giants that formed from the mix of cold, neutral hydrogen gas that was a key part of the universe’s early makeup. They were also supernovas that only lasted about 100 million years before exploding and helping “forge heavier elements” that served as the building blocks of younger stars.

“They really lay the seeds for everything that comes after them,” said Arizona State University experimental astrophysicist Judd Bowman, lead author on the new study published this week in the journal Nature.

Due to the constant expansion of the universe, it’s extremely hard to prove the existence of these very early stars, even for NASA’s sophisticated Hubble Space Telescope. But astronomers have been studying the Big Bang’s cosmic microwave background (CMB) for the past few years, and had recently discovered that this radiation, once blended in with the same neutral hydrogen that gave birth to the first stars in the universe, might hold some sort of proof that those stars had existed. BBC News explained that this is due to ultraviolet starlight exciting the hydrogen atoms in such a way that the CMB is absorbed by the gas at a radio frequency of exactly 1.4 gigahertz.

Using a rather peculiar yet simple instrument, a 6.4-foot-long, dinner-table-like radio telescope at Western Australia’s Murchison observatory, the researchers attempted to spot the aforementioned signal. Although it proved hard to isolate the signal from the “sea of radio noise” from the sky, BBC News noted that the researchers found it at a much lower frequency of 78 megahertz, further deducing that the hydrogen/starlight interaction they spotted might have taken place about 180 million years after the Big Bang.

The astronomers behind the new study also concluded that the hydrogen gas was about twice as cold than originally thought, which makes it possible that the hydrogen atoms had directly come in contact with dark matter. Although there has been no confirmed interaction of this kind in scientific literature, BBC News wrote that the new discovery might be the first of its kind to suggest that the substance does more than just influence gravitational pull, and one that could encourage scientists to work hard toward finally discovering “dark matter particles.”

“I think it’s a little bit like winning the lottery, in a sense,” said MIT radio astronomer and study co-author Alan Rogers.

Harvard University theoretical astrophysicist Avi Loeb, who was not involved in the study, told the Los Angeles Times that the findings, should they be accurate, are “Noble Prize-worthy” twice over.

“Not only did they detect the signal, but it actually is bigger than one can accommodate in the standard cosmological model. And you need new physics in order to explain a signal as big as they detected.”

Regarding the theory that the hydrogen became so cold because of dark matter, Tel Aviv University researcher Rennan Barkana wrote a separate paper on the topic, also published this week in Nature. While this could effectively challenge the long-held theory that dark matter can only interact with regular matter through gravity, NPR noted that the main takeaway from the research is that another team of scientists needs to corroborate the new findings from Bowman’s study first, by spotting that very same radio signal from our universe’s first stars.