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A Victory for Dark Matter in a Galaxy Without Any

30 March 2018

What has scientists so curious about this galaxy is that it is unusually transparent and appears to contain no dark matter.

"NASA's Hubble Space Telescope took an image of a freaky, ghostly looking galaxy called NGC 1052-DF2 that astronomers calculate to have little to no dark matter". "There's a pretty tight relationship between the amount of stars that formed and the dark matter there, at least when the galaxy formed". They only know dark matter does exist everywhere and has its own gravitational pull. But there is no theory as to why dark matter would be missing in galaxies when it was thought to be their building block.

Before, scientists believed that galaxies were composed of stars, gases and dark matter, all mixed together.

Roberto Abraham, left, Pieter van Dokkum, right, and their team of University of Toronto and Yale University graduate students pose with one-half of the 48-lens Dragonfly array at its home site in New Mexico.

The clusters, they found, travelled at the same speed as the galaxy, itself moving through the Universe. "So then, if you find a galaxy that appears not to have dark matter, you have to ask, 'How was it formed?'"

NGC 1052-DF2 resides about 65 million light-years away in the NGC 1052 Group, which is dominated by a massive elliptical galaxy called NGC 1052.

Dark matter and dark energy comprise the rest, and scientists have yet to directly observe either. Usllay galaxies have a larger mass than can be accounted for just by the ordinary matter inside them.

Now, while using a new telescope, known as the Dragonfly Telescope Array, astronomers looking for faint, hard-to-find objects out in the universe, have found what they call an "Ultra-Diffuse Galaxy", named NGC1052-DF2 (DF2 for short), which has them scratching their collective heads. "I spent an hour just staring at the Hubble image", van Dokkum said. That gas can then, in principle, contract and form a little galaxy (a "tidal dwarf"). One suggestion is that the gas obtained focused as it was being expelled from a galaxy merging; an additional is that it created from issue gushed out by quasars. At the observatory William Myron Keck on the island of Hawaii, they measured the mass of this galaxy.

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The researchers suggest that the somewhat-odd appearance of the globular clusters is probably related to the galaxy's unexpected properties, and they announced they're working on a paper that will describe those.

Theories that challenge dark matter's existence will need to explain away the new claim about galaxy NGC 1052-DF2 to survive.

To imagine this process, you can visualize dark matter as a diffuse collection of individual particles-unlike ordinary matter, which clumps into stars and planets.

Scientists have various theories on how this galaxy came to be.

"Instead we saw the opposite, leading to this remarkable conclusion that there's actually no room for dark matter at all in this thing", van Dokkum says. But a small, distant galaxy is challenging everything we thought we knew about galaxy formation. They followed the motion of 10 star clusters to work out how much mass the galaxy had.

Unfortunately, dark matter research is facing a hurdle, as the Trump administration's NASA budget proposal for fiscal year 2019 places the funding of the Wide-Field Infrared Survey Telescope in question. "It is completely unknown how it is possible to form such a galaxy".

Case Western Reserve astronomer Stacy McGaugh confirmed that the findings make no sense, but, well, there they are anyway.

A Victory for Dark Matter in a Galaxy Without Any