Dark matter is seen for the first time in eerie image

Scientists have captured the first–ever direct evidence for dark matter, the elusive substance that makes up more than a quarter of the universe.

Using NASA's Fermi telescope, researchers have detected powerful gamma–ray radiation emerging from a 'halo–like' structure surrounding the Milky Way.

Its frequency and intensity suggest that this could be dark matter.  

According to the study's author, Professor Tomonori Totani of the University of Tokyo, this eerie image is the first time that humanity has been able to 'see' the mysterious substance. 

For almost two decades, scientists have known that there is a glow of gamma–ray radiation coming from the heart of the Milky Way called the galactic centre (GC) excess.

However, the so–called 'halo signature' surrounding our galaxy is something that no scientist has ever seen before.

Speaking to Daily Mail, Professor Totani explained: 'While the GC excess is concentrated at the very centre of the Galaxy, my halo signal is thinly spread across the halo region.

'I believe it strongly suggests radiation from dark matter.'

The invisible influence of dark matter helps explain everything from the rotation of galaxies to the expansion of the universe.

But, despite its enormous importance to modern physics, scientists have only been able to observe dark matter indirectly by measuring its gravitational effects.

Now, Professor Totani believes he has finally found a way to change this.

Many scientists believe that dark matter is made up of something called weakly interacting massive particles, or WIMPs.

WIMPS are much larger than normal particles like protons, but don't interact with conventional matter – making them almost impossible to detect.

However, when two WIMPs collide, they are annihilated and release a burst of photons in the form of gamma–ray radiation.

Using 15 years of data from NASA's Fermi Gamma–ray Space Telescope, Professor Totani looked at a region of the galaxy where dark matter was thought to collect.

There, he found that gamma rays with an 'extremely large amount of energy' extend in a large halo–like structure, emerging from the galactic centre.

What is dark matter?

Dark matter outweighs visible matter roughly six to one, making up about 27 per cent of the universe. 

Unlike normal matter, dark matter does not interact with the electromagnetic force. 

This means it does not absorb, reflect or emit light, making it extremely hard to spot.

In fact, researchers have been able to infer the existence of dark matter only from the gravitational effect it seems to have on visible matter. 

Source: CERN 

This energy was emerging from the exact place where previous studies had predicted dark matter would be most concentrated.

Even more excitingly, this energy level is exactly what some scientists had predicted colliding particles of dark matter should produce.

This could very well be the first time that scientists have found a way of looking at dark matter itself.

Professor Totani told Daily Mail: 'Since we are directly observing the gamma rays emitted by dark matter, I personally believe it can be considered "direct observation".'

Importantly, the halo signature is completely distinct from previous observations of the GC excess.

Not only is the halo signature more spread out, but it is also 10 times more powerful than the gamma radiation found in the GC excess.

This is critical because there are no known types of stars or black holes which produce this type of energy.

Dr Moorts Muru, a dark matter expert from the Leibniz Institute for Astrophysics who was not involved in the study, told Daily Mail: 'None of the known stellar objects radiates energy at such high levels, and thus, Totani leans strongly towards the dark matter hypothesis.'

While Dr Muru says this is not 'definitive proof', he adds that it is a 'significant boost to understanding dark matter'.

However, not everyone is convinced.

Professor Joe Silk, a dark matter researcher from Johns Hopkins University who was not involved in the study, told Daily Mail he thinks the claim of dark matter detection is 'premature'.

Firstly, Professor Totani's predictions for how much energy a WIMP should produce are much higher than some scientists' calculations.

'Of course, our predictions could be wrong, but if he is correct, we should have seen a gamma ray signal from nearby dwarf galaxies that are dark matter–dominated,' says Professor Silk.

Additionally, Professor Silk argues that these strong gamma rays could be the product of a huge explosion that emanated from the galaxy's central black hole about 10 billion years ago.

This explosion created the massive structures known as the 'Fermi bubbles' that extend on either side of the galaxy, but could have also started a powerful chain reaction.

Professor Silk says: 'What he did not consider is the fact that such an explosion that caused the Fermi bubbles is associated with violent shock fronts with turbulent magnetic fields that are known to be giant particle accelerators.

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'So they could have injected many energetic particles whose subsequent diffusion and interaction with the ambient gas would have generated an additional gamma ray glow. In which case, we have no evidence for dark matter.'

In his paper, published in the Journal of Cosmology and Astroparticle Physics, Professor Totani acknowledges that more observations will be needed to prove this really is dark matter.

If other regions that should have lots of dark matter, like nearby dwarf galaxies, have similar gamma–ray signatures, it would be strong evidence for his claim.

However, the researcher remains confident that more data in the future will only provide more evidence that gamma–rays originate from dark matter.