Categories: AstronomyDark Matter

A new way to map out dark matter is 10 times more precise than the previous-best method

Astronomers have to be extra clever to map out the invisible dark matter in the universe. Recently, a team of researchers have improved an existing technique, making it up to ten times better at seeing in the dark.

Dark matter is frustratingly difficult to measure. It’s completely invisible: it simply doesn’t interact with light (or normal matter) in any way, shape, or form. But we know that dark matter exists because of its gravitational influence on everything around it – including the normal matter that makes up stars and galaxies.

As an example of this, take a look at gravitational lensing. A massive object, whether made of dark or normal matter, will bend the path of any light that passes close by. It’s usually an incredibly tiny effect, but definitely measurable. We can see lensing of starlight around the sun, for example, which is how we knew that Einstein’s theory of general relativity must be correct.

When light from a very distant galaxy passes through or a near a slightly-less-distant massive object, like a galaxy cluster, that light gets bent. We can use that distortion to measure the amount of dark matter in the galaxy cluster, and is one of our primary ways of mapping dark matter in the universe.

But we usually don’t get this sort of lucky alignment, so instead we have to turn to a different technique: weak gravitational lensing. To make this work, astronomers take a survey of a whole slew of galaxies and look for tiny little distortions in each one. Individually, it’s not much, but taken together it can provide a map of a large region of dark matter.

Recently, a team of astronomers improved on this idea by adding in the rotation of the observed galaxies, as reported in a recent paper published in the Monthly Notices of the Royal Astronomical Society.

Since we know how galaxies ought to rotate, we can combine the distortions in their shapes with the distortions in their internal movements to get a lot more bang for the observational buck, yielding a technique to map dark matter up to ten times more powerful than shapes alone.

Paul M. Sutter

Astrophysicist, Author, Host |

Recent Posts

The UK is Considering Nuclear Propulsion in Space

The UK Space Agency recently contracted with the British Rolls Royce company to research nuclear…

21 hours ago

James Webb Unfolds Sunshield

It’s almost time. Soon the James Webb Space Telescope will be on its way to…

23 hours ago

Thanks to Perseverance, We’re Finally Going to Hear What Mars Sounds Like

Many consider the various rovers we’ve sent to Mars as the next best thing to…

1 day ago

NASA Has Given Up on Trying to Deploy InSight’s Mole

It's always a sad day when a mission comes to an end. And it's even…

2 days ago

Mars is Still an Active World. Here’s a Landslide in Nili Fossae

A image released by the MRO mission shows a landslide near the location where the…

2 days ago

Astronomers see a Hint of the Gravitational Wave Background to the Universe

Astronomers have found evidence of faint gravitational waves using an array of pulsars in our…

2 days ago