‘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.
