Published: Fri, March 02, 2018
Research | By Raquel Erickson

Astronomers detect signal of Universe's first stars

Astronomers detect signal of Universe's first stars

Scientists only know of dark matter - an enigmatic force that's thought to make up about 27 percent of the universe - through its gravitational effects.

It was not only the earliest detection of hydrogen in the universe but also proved that the first stars might have lit up around that time, making way for the cosmic dawn that moved the universe out of darkness, said Alan Rogers, the study's coauthor and a scientist at MIT's Haystack Observatory.

The earliest stars were the source of all heavy elements in the Universe, including those necessary for life to exist. Ultra-violet radiation disturbed the hydrogen atoms, leading to a characteristic signal emission. The evidence hints that the gas that made up the early Universe was colder than predicted.

What were those first stars like and when did they form? Scientists discovered signals coming from the first stars of the Universe.

"What's happening in this period is that some of the radiation from the very first stars is starting to allow hydrogen to be seen".

The signal is a fingerprint left on background radiation by hydrogen that absorbed some of this primordial light.

"The whole history of the early universe was vital for seeding all of the structures that we see in the universe today", said Carole Haswell, Head of Astronomy at the Open University.

Bowman has been searching for the elusive trace of star ignition for 12 years. "The first stars in the universe turned on the radio signal, while the dark matter collided with the ordinary matter and cooled it down".

It also potentially reveals something new about the nature of dark matter.

Even without the possible dark matter connection, the discovery is groundbreaking.

It can not be seen directly with telescopes, but astronomers know it to be out there because of its gravitational effects on known matter. For the moment, that is just a suggestion and a way of explaining the unexpected data - but if proven right could shed light on one of the greatest mysteries of the universe.

"The first indication of the signal emerged within weeks of turning on the instrument in 2015", says Judd Bowman of Arizona State University, a coauthor of the study presenting the results in Nature.

He noted that other astrophysicists may come up with differing explanations for the signal's size once they've had time to analyse it.

"These new studies open up new possibilities in this research field. As far as we know, there was only one thing in the Universe at that time that was colder than the neutral hydrogen: dark matter".

Antennae in the Australian desert listen out for signals from Space. The important detection was found among sources of noise that can be a thousand times louder than the actual signal, which Peter Kurczynski, from the USA government's National Science Foundation likened to "being in the middle of a hurricane and trying to hear the flap of a hummingbird's wing". "This project shows that a promising new technique can work and has paved the way for decades of new astrophysical discoveries".

We use the speed of light when measuring vast distances in the universe like the space between stars and galaxies. "If you think about, how did humans get here, basically the first rung on the ladder is you need something in the universe".

The current version of EDGES is the result of years of design iteration and instrument calibration in order to reach the levels of precision necessary for successfully achieving an extremely hard measurement. If the find is confirmed, it could give scientists a peek into the universe's ancient origins.

"Astronomers worldwide will be holding their breath until the result is confirmed by an independent experiment", added Karl Glazebrook of the Swinburne University of Technology in comments via the Science Media Centre in Australia.

Then, they set the equipment up at the Murchison Radio-astronomy Observatory (MRO) in Western Australia.

According to the scientist, the first stars were not similar to modern. A confirmation would be highly useful, given how fine the measurements the EDGES device was performing. "The fact that the detection is much stronger than expected, and that can be easily explained, is particularly exciting".

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