Scientists have finally FOUND the universe's 'missing matter': Elusive substance is discovered in 10 million degree filament - addressing a decades-long mystery

Daily Mail​

19-06-2025

After 10 years of searching, scientists have finally found the universe's 'missing matter'.
For our cosmological models to work, scientists know there should be a certain amount of matter - the substance that makes up everything we can see - out in the universe.
The problem is that only a third of this matter has ever been seen, while the rest is missing.
Now, experts from the European Space Agency say they may have solved the mystery.
They believe the 'missing' matter lies in a vast filament of 10-million-degree gases stretching across the depths of the universe.
At over 23 million light-years in length, this cosmic ribbon contains 10 times as much matter as the Milky Way.
The enormous thread connects four galaxy clusters, each containing thousands of individual galaxies filled with billions of stars.
'It seems that the "missing" matter may truly be lurking in hard-to-see threads woven across the universe,' said co-author Dr Norbert Schartel, a project scientist on the European Space Agency's (ESA) XMM-Newton telescope.
The filament stretches diagonally away from Earth as part of the Shapley Supercluster - a collection of 8,000 galaxies which is one of the biggest structures in the universe.
The thread is so long that travelling its length would be like crossing the Milky Way end-to-end more than 230 times.
As its gases collapse inwards under gravity, they produce vast amounts of energy which causes the gas to become extremely hot.
However, because the gas is so spread out, filaments only give out a very faint light which is hard to distinguish from that of nearby galaxies and black holes.
Lead researcher Dr Konstantinos Migkas, of the Leiden Observatory in the Netherlands, told MailOnline: 'Throughout this thin, diffuse, low-emitting gas, there are many supermassive black holes that emit a lot of X-ray radiation, overcrowding the signal from the filaments and their gas.
'It's like trying to see a candlelight next to 10 luminous flashlights from 100 meters away.'
Without being able to isolate the light coming from the gas itself, astronomers haven't been able to work out how much of the universe's hidden mass it contains.
In a new paper, published in the journal Astronomy and Astrophysics, astronomers have managed to do this for the very first time using two powerful X-ray telescopes.
Using powerful space telescopes, astronomers were able to distinguish the gas' X-ray radiation from contaminating sources such as supermassive black holes
Why does the universe have missing matter?
To figure out how the universe has evolved, cosmologists have created simulations called models.
These models have been highly successful at predicting the distribution of galaxies and other structures.
The models also tell scientists that there should be a certain amount of normal matter in the universe.
However, only about 20 to 30 per cent of the predicted matter has ever been seen.
If this matter does exist, it might be spread out in filaments of gas connecting dense clusters of galaxies.
If not, this suggests that scientists' best models of the universe are wrong after all.
The researchers combined observations from the ESA's XMM-Newton and the Japan Aerospace Exploration Agency's (JAXA) Suzaku X-ray space telescopes.
While Suzaku mapped out gas' faint X-ray radiation over a large area, XMM-Newton was able to pinpoint sources of contaminating X-rays such as supermassive black holes.
Co-author Dr Florian Pacaud, of the University of Bonn, says: 'Thanks to XMM-Newton we could identify and remove these cosmic contaminants, so we knew we were looking at the gas in the filament and nothing else.'
For the first time ever, that has allowed scientists to work out the properties of a cosmic filament.
The exciting part for scientists is that these observations confirm that their models of the universe were correct all along.
Dr Migkas says: 'From cosmological, large-scale structure simulations that resemble the universe, we see that this still-missing matter should reside in these strings of gas and galaxies and this matter also should have a certain temperature and density.
'In our study, we confirm for the first time unambiguously that indeed, there are cosmic filaments with exactly the right density and temperature of the gas, as predicted by our current model of cosmology.'
That is a very good indication that the large-scale structure of the local universe does look like scientists' predictions suggest.
In addition to revealing a previously unseen thread of matter running through the universe, these findings show galaxy clusters are connected over vast distances.
That means some of the densest, most extreme structures in the universe could be part of a vast 'cosmic web'.
This is an invisible cobweb of filaments that may underpin the structure of everything we see around us.
Now, we are one step closer to understanding how that network fits together.
WHAT IS THE COSMIC WEB OF FILAMENTS THAT THE UNIVERSE IS MADE UP OF?
'Ordinary' matter, which makes up everything we can see, corresponds to only five per cent of the known universe. The rest is made up of so-called 'dark matter.'
For decades, at least half of this regular matter had eluded detection, but scientists have in recent years made the first direct observations of a 'cosmic web' of filaments spanning between galaxies.
These filaments are made up of gas at temperatures between 100,000°C (180,032 °F) and 10 million°C (50 million°F) and the experts believe these structures may account for the 'missing' ordinary matter.
Studies have estimated that around 95 per cent of the universe is made of a mixture of 'dark matter' and 'dark energy', which only makes its presence felt by its gravitational pull, but has never been seen directly.
What is less widely known, however, is that around half of the regular matter is also missing.
In 2015, a team led by University of Geneva scientist Dominique Eckert claimed that these 'missing baryons' - subatomic particles made up of three quarks - were detected because of their X-ray signature in a massive cluster of galaxies known as Abell 2744.
Using the XMM-Newton space telescope, the researchers found matter concentrated into a network of knots and links connected through vast filaments, known as the 'cosmic web'.
Large-scale galaxy surveys have shown that the distribution of ordinary matter in the universe is not homogeneous.
Instead, under the action of gravity, matter is concentrated into so-called filamentary structures, forming a network of knots and links called the 'cosmic web'.
The regions experiencing the highest gravitational force collapse and form the knots of the network, such as Abell 2744.
Researchers focused on Abell 2744 - a massive cluster of galaxies with a complex distribution of dark and luminous matter at its centre - to make their finding.
Comparable to neural networks, these knots then connect to one another through filaments, where the researchers identified the presence of gas, and consequently, the missing ordinary matter thought to make up the universe.