Scientists may have uncovered evidence of dark matter
- Scientists announced they’ve found signals from earliest stars in the universe
- In a second paper, researcher says they also detected evidence of dark matter
- If found to be true, this would finally confirm the existence of the elusive particle
Published: 21:55 GMT, 28 February 2018 | Updated: 22:02 GMT, 28 February 2018
Scientists searching for the earliest stars in the universe have stumbled upon what could be the first direct evidence of dark matter.
The mysterious invisible substance is thought to make up roughly 27 percent of the universe – but, it’s continued to elude detection since it was first theorized, instead making its presence known only through its gravitational effects on objects in space.
Now, astrophysicists have uncovered a ‘surprising’ signal that could upend what we know about dark matter and, if confirmed, finally prove its existence.
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Though dark matter accounts for a crucial part of the standard model of cosmology – making up about 27 percent of the material in the universe and nearly 85 percent of its total mass – scientists have never directly observed it. An artist's impression of the Big Bang is shown
An international team of scientists announced today that they’ve spotted signals from the earliest stars in the universe, using the EDGES radio telescope to peer back to 180 million years after the Big Bang.
And, in doing so, they may inadvertently have made another groundbreaking discovery.
In a second paper published this week to the journal Nature based on the findings, a researcher from Tel Aviv University argues that the team has detected signals that could indicate the presence of dark matter.
‘Dark matter is the key to unlocking the mystery of what the universe is made of,’ says Professor Rennan Barkana of Tel Aviv University.
‘We know quite a bit about the chemical elements that make up the Earth, the sun, and other stars, but most of the matter in the universe is invisible and known as “dark matter.”
‘To solve it, we must travel back in time. Astronomers can see back in time, since it takes light time to reach us.
‘We see the sun as it was eight minutes ago, while the immensely distant first stars in the universe appear to us on Earth as they were billions of years in the past.’
Microwave radiation from the whole sky, captured by the European Space Agency's Planck satellite, is shown. Yellow indicates the 'relic radiation' created in the Big Bang
In the study, the researchers detected a radio wave signal at a frequency of 78 megahertz.
While its width lines up with the expectations, the scientists discovered the signal had a much larger amplitude than predicted.
This corresponds with deeper absorption, suggesting that this ancient gas was much colder than expected.
And, this may have cooled through interactions with cold, dark matter.
‘I realized that this surprising signal indicates the presence of two actors: the first stars, and dark matter,’ Barkana says.
‘The first stars in the universe turned on the radio signal, while the dark matter collided with the ordinary matter and cooled it down.
‘Extra-cold material naturally explains the strong radio signal.’
A timeline of the universe, updated to show when the first stars emerged. This timeline reflects the recent discovery that the first stars emerged by 180 million years after the Big Bang
This artist's rendering shows the universe's first, massive, blue stars embedded in gaseous filaments, with cosmic microwave background visible at the edges. Using radio observations of the distant universe, researchers discovered the influence of early stars on primordial gas
The signal also suggests that dark matter may be composed of low-mass particles, each being no heavier than several proton masses, according to the researchers.
If this is the case, dark matter would be less massive than previously suspected.
‘This insight alone has the potential to reorient the search for dark matter,’ Professor Barkana says.
The new findings could have huge implications for our understanding of the universe.
Though dark matter accounts for a crucial part of the standard model of cosmology – making up about 27 percent of the material in the universe and nearly 85 percent of its total mass – scientists have never directly observed it.
And to date, there has been no evidence that dark matter can ‘touch’ regular matter – let alone cool it, explains astrophysicist Katie Mack, in a blog post for Scientific American.
WHAT IS DARK MATTER?
Dark matter is a hypothetical substance said to make up roughly 27 per cent of the universe.
The enigmatic material is invisible because it does not reflect light, and has never been directly observed by scientists.
It cannot be seen directly with telescopes, but astronomers know it to be out there because of its gravitational effects on known matter.
The European Space Agency says: 'Shine a torch in a completely dark room, and you will see only what the torch illuminates.
Dark matter is a hypothetical substance said to make up roughly 27 per cent of the universe. It is thought to be the gravitational 'glue' that holds the galaxies together (artist's impression)
'That does not mean that the room around you does not exist.
'Similarly we know dark matter exists but have never observed it directly.'
Dark matter is thought to be the gravitational 'glue' that holds the galaxies together.
Just five per cent the observable universe consists of known material such as atoms and subatomic particles.
‘If this signal really is detecting a new kind of dark matter interaction, it’s not only the first confirmation of dark matter making its presence felt, it’s also a magnificent confirmation that dark matter is a real, tangible component of the cosmos,’ Mack writes.
‘In short, if this signal is what it looks like, it changes everything.’
For now, it’s too early to say if the signals truly confirm the presence of dark matter.
With additional studies using radio telescopes such as the Square Kilometer Array (SKA), however, the experts think it could be possible to detect the specific pattern of radio waves produced by dark matter.
Such an observation, according to Barkana, ‘would confirm that the first stars indeed revealed dark matter.’