Bowman said they investigated possible explanations and reached out to close colleagues for assistance and ideas.
“It is difficult to find mechanisms that could increase the radio background at this age in the universe, whereas an explanation for how the gas might be cooler than expected was more assessable,” he said.
One colleague, Rennan Barkana from Tel Aviv University had an intriguing idea based on previous observations. The gas could have been cooled through the interaction of hydrogen with something quite cold: dark matter.
“Barkana realized that previous work exploring the possible effects of dark matter interacting with baryons — atoms, for example — could be applied to the era probed by our observations and would provide a mechanism for cooling the gas to the needed temperature,” Bowman said. “In essence, if the gas interacts — even weakly — with dark mater, it could lose energy to the dark matter and cool. This is the best explanation we have at the moment and it is very exciting if it holds.”
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Bowman added that additional ideas will likely emerge as more astrophysicists analyze their research. But, he said, it is hard to conjure up any other objects or processes that can have such an effect at these early ages.
But thanks to upgrades to the antenna and other systems of EDGES made by Bowman and fellow astronomers at ASU, MIT, and the University of Colorado, the scientists were especially intrigued to find signature of light from the first stars and that the profile of the radio waves match theoretical predictions of what would be produced if hydrogen were indeed influenced by the first stars.
"It is unlikely that we'll be able to see any earlier into the history of stars in our lifetimes," Bowman said in a statement. "This project shows that a promising new technique can work and has paved the way for decades of new astrophysical discoveries."