Einstein rings get us closer to solving dark matter debate

Physicists imagine many of the matter within the universe is made up of an invisible substance that we solely learn about by its oblique results on the celebrities and galaxies we are able to see.

We’re not loopy! With out this “dark matter,” the universe as we see it might make no sense.

However the nature of dark matter is a longstanding puzzle. Nevertheless, a new study by Alfred Amruth on the College of Hong Kong and colleagues, revealed in Nature Astronomy, makes use of the gravitational bending of sunshine to convey us a step nearer to understanding.

Invisible however omnipresent

The explanation we predict dark matter exists is that we are able to see the results of its gravity within the habits of galaxies. Particularly, dark matter appears to make up about 85 p.c of the universe’s mass, and many of the distant galaxies we are able to see look like surrounded by a halo of the thriller substance.

Nevertheless it’s referred to as dark matter as a result of it doesn’t give off mild, or take in or replicate it, which makes it extremely tough to detect.

So what’s these items? We predict it have to be some sort of unknown elementary particle, however past that we’re unsure. All makes an attempt to detect dark matter particles in laboratory experiments to this point have failed, and physicists have been debating its nature for many years.

Scientists have proposed two main hypothetical candidates for dark matter: comparatively heavy characters referred to as weakly interacting large particles (or WIMPs), and very light-weight particles referred to as axions. In idea, WIMPs would behave like discrete particles, whereas axions would behave much more like waves on account of quantum interference.

It has been tough to tell apart between these two potentialities — however now mild bent round distant galaxies has supplied a clue.

Gravitational lensing and Einstein rings

When mild touring via the universe passes an enormous object like a galaxy, its path is bent as a result of — in accordance with Albert Einstein’s idea of basic relativity — the gravity of the huge object distorts space and time round itself.

Because of this, generally once we have a look at a distant galaxy we are able to see distorted photographs of different galaxies behind it. And if issues line up completely, the sunshine from the background galaxy might be smeared out right into a circle across the nearer galaxy.

This distortion of sunshine known as “gravitational lensing,” and the circles it could possibly create are referred to as “Einstein rings.”

By finding out how the rings or different lensed photographs are distorted, astronomers can study in regards to the properties of the dark matter halo surrounding the nearer galaxy.

Axions versus WIMPs

And that’s precisely what Amruth and his crew have finished of their new examine. They checked out a number of programs the place a number of copies of the identical background object had been seen across the foreground lensing galaxy, with a particular give attention to one referred to as HS 0810+2554.