![]() ![]() “The first stars in the Universe turned on the radio signal, while the dark matter collided with the ordinary matter and cooled it down. "I realised that this surprising signal indicates the presence of two actors: the first stars, and dark matter," says Professor Rennan Barkana of Tel Aviv University. One striking possibility is that dark matter interactions may explain the effect. The signal that Bowman’s team untangled was twice as intense as models had predicted, suggesting that either the hydrogen gas so soon after the Big Bang was colder than expected or that background radiation levels were significantly hotter than the photons of the CMB. The NSF funds the Experiment to Detect the Global EoR (Epoch of Reionisation) Signature (EDGES) project, the antenna which detected this archaic signal and an instrument that looks much like a glass table randomly placed in the outback of Western Australia.ĭetecting the signal is cause enough for celebration, however an unanticipated result gleaned from the data suggests that something else might be at play too. However distinguishing these signals from the medley of radio-signals that are produced by the inhabitants of our planet, is like trying to hear the flap of a hummingbird's wing in the middle of a hurricane, commented Peter Kurczynski, program director for the National Science Foundation (NSF). "Telescopes cannot see far enough to directly image such ancient stars, but we've seen when they turned on in radio waves arriving from space,” added Bowman. These atoms also began to absorb surrounding CMB photons causing a small dip in its intensity, a feature that would be noticeable in the CMB signals that eventually reached Earth. Previous research had indicated that the first stars would have released tremendous amounts of ultraviolet (UV) light and that this light could have interacted with free-floating hydrogen atoms. So astronomers looked to other means in which to identify the light. As such optical telescopes would struggle to see any light that was emitted from these behemoths before they likely exploded as supernovas. It has long been suspected that the first stars would be massive and therefore short-lived. "Finding this minuscule signal has opened a new window on the early universe," says astronomer Judd Bowman of the University of Arizona, the lead investigator on the project. The signal, which has left its imprint in the cosmic microwave background (CMB) – the background electromagnetic radiation that permeates the Universe – confirms that the ancient suns were active within 180 million years of the Big Bang. This prodigious breakthrough is even more remarkable, because the detection was made not with a large array of telescopes but with a radio antenna not much larger than a refrigerator. Two different teams of astronomers have not only detected light from the first stars that shone in the Universe but have also unexpectedly stumbled upon "dark matter,” the mysterious matter that does not absorb, reflect or emit light and is roughly six times more abundant than the visible material we see around us. ![]()
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