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Look at dark matter under a new light



Look at dark matter under a new light

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7;s impression of a galaxy surrounded by gravitational distortion caused by dark matter. Galaxies live inside larger concentrations of invisible dark matter (purple in this figure), however the effects of dark matter can be seen by looking at the distortion of galaxies. background. Credit: Swinburne Astronomy Productions – James Josephides

A small group of astronomers have found a new way to ‘see’ elusive dark matter haloes surrounding galaxies, with a new technique 10 times more accurate than the best method. before. Works are published in Royal Astronomical Society monthly announcement.


Scientists currently estimate that up to 85% of the mass in the universe is invisible. This “dark matter” cannot be observed directly, because it does not interact with light in the same way that ordinary matter makes up the stars, planets and life on Earth.

So how do we measure what cannot be seen? It is important to measure the effect of the gravitational force that dark matter exerts.

Pol Gurri, Ph.D. “It’s like looking at a flag to try to know how much wind is. You can’t see the wind, but the movement of the flag,” explained a student at Swinburne University of Technology. tells you how strong the wind is blowing. “

The new study focuses on an effect called the weak gravitational lens, a feature of Einstein’s general theory of relativity. Associate professor Edward Taylor, who was also involved in the study, said: “Dark matter will very little distort the image of whatever is behind it. “The effect is a bit like reading a newspaper through the bottom of a wine glass.”

Look at dark matter under a new light

The processed image of a spiral galaxy, as can be observed after the lens effects have distorted the true shape of the galaxy. By measuring the orbital motion of gas in a distant galaxy (seen here in pink), the gravitational distortions can be measured much more accurately than before. Photo Provider: Original images of ESA / Hubble & NASA / Flickr users in Det58, image editing by Pol Gurri

A weak gravitational lens has been one of the most successful ways to map the dark matter content of the Universe. Now, the Swinburne team has used the 2.3m ANU Telescope in Australia to map how galaxies with gravitational lenses are rotating. “Because we know how stars and gas are thought to move inside galaxies, we know almost what that galaxy will look like,” Gurri said. “By measuring the amount of distortion in the real galactic image we can then figure out how much dark matter to explain what we see.”

This new study shows how this velocity information allows for much more precise measurement of lens effects than just using shape. “With our new view of dark matter, we hope to get a clearer picture of where dark matter is and its role in how galaxies form,” Gurri said.

Look at dark matter under a new light

An image of the 2.3m telescope taken by the Australian National University (ANU) at the Siding Spring Observatory. Credit: Australian National University

Future space missions such as NASA’s Nancy Grace Roman Space Telescope and the European Space Agency’s Euclid Space Telescope are partly designed to make these types of measurements based on geometry. form of hundreds of millions of galaxies. “We have shown that we can make a real contribution to these global efforts with a relatively small telescope built in the 1980s, just by thinking about the problem,” said Taylor. deals in a different way.


Dark matter and large galaxies


More information:
Pol Gurri et al. First cut measurements from a weak, precise lens, Royal Astronomical Society monthly announcement (Year 2020). DOI: 10.1093 / mnras / staa2893

Provided by the Royal Astronomical Society

Quote: Seeing dark matter in new light (2020, November 6) retrieved November 7, 2020 from https://phys.org/news/2020-11-dark.html

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