When did the first stars turn on in the universe? This grand question motivates new observations that may change the way we think about the first stars and, in a surprising turn of events, also about the mysterious dark matter in which the stars are embedded.
The discovery is reported in the most recent issue of Nature magazine by Principal Investigator Dr. Judd Bowman. Dr. Bowman and his team of astronomers used a radio telescope for this experiment which operates at frequencies close to your those of your favorite radio stations on the FM dial!
The idea is that if there were stars existing when the universe was a mere 180 million years old, then the starlight would change the absorbing properties of the abundant neutral hydrogen atoms surrounding the stars. This change would allow an absorption to be detected by the hydrogen as it interacts with the all-pervasive cosmic microwave background radiation.
Astronomers expected that there would eventually be an indirect detection of the first stars by this radio telescope approach, so at first this discovery was not so surprising. But, when the detection was finally made, the amplitude turned out to be roughly twice the strength of the predicted value.
This is a door-opening discovery to an still larger discovery. It appears that there must be some other component of matter operating in conjunction with the first stars to increase the amount of absorption in the hydrogen gas. That new component may be dark matter, according to a companion paper also presented in Nature magazine by Renan Barkana.
To explain the observations, the dark matter will need to be lighter than predicted by the models. Additional tests are needed take into account all the possible systematic errors. Even so, this discovery provides another route for astronomers and physicists to start an investigation for a new potential "low-fat" version of the elusive dark matter particle.