Measurements made with Keck and Gemini Observatory, both on Maunakea, the Hubble Space Telescope and others showed that NGC 1052-DF2, an ultra-diffuse galaxy, followed a different path. NGC 1052-DF2 resides about 65 million light-years away in a collection of galaxies that is dominated by the giant elliptical galaxy NGC 1052. "It's so rare, particularly these days after so many years of Hubble, that you get an image of something and you say, 'I've never seen that before.' This thing is astonishing: a big blob that you can look through. It is literally a see-through galaxy".
Using the University of Toronto's Dragonfly Telescope Array, researchers found that this galaxy belonged to a recently discovered class of galaxies called ultra diffuse galaxies, those that are large but extremely low-mass.
"Finding a galaxy without dark matter is an oxymoron", says van Dokkum. That gas can then, in principle, contract and form a little galaxy (a "tidal dwarf").
Every galaxy that has been spotted contained a dark matter signature.
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Dark matter is the bedrock that all galaxies are anchored to.
Paradoxically, the authors said the discovery of a galaxy without dark matter counts as evidence that it probably does exist.
He also raised the possibility that another galaxy nearby was tweaking NGC 1052-DF2's motion through an element of MOND called the "external field effect". "NGC1052-DF2 challenges the standard ideas of how we think galaxies form", said van Dokkum. It is about the size of our own galaxy, but only one-hundredth of its stars, while - unlike ours - it does not have a black hole in its center.
Each of these would certainly have to be analyzed in information to identify if it can develop the distinctive attributes of NGC1052- DF2.
Andrew Pontzen, a cosmologist at University College London who was not involved in the work, said: "Alternative gravity theories tend to be tuned to reproduce typical galaxies, which means they can struggle to account for anything new or unusual". There's generally a lot a lot more dark issue compared to average things in many galaxies, so the writers wrap up that, "NGC1052- DF2 is exceptionally lacking in dark issue, and also a great prospect for a "baryonic galaxy" with no dark issue at all". Yet in this odd galaxy, the projected signatures of these exotic effects are not seen. This study was published in Nature. "So finding the opposite, namely an absence of dark matter, really came out of the blue for us", he said. It may have been formed from gas interaction blowing out or into a larger galaxy.
Dark matter is believed to exist because of its gravitational effects on visible matter in the cosmos. When dark matter is present, that galaxy's gravity will be bulked up, causing its stars to move faster than if just normal matter were present. The researchers figured out NGC 1052-DF2's spin speed by looking at the movement of 10 objects in the region of the galaxy. They can't agree on what it's made of, how much a single particle weighs, or the best way to construct a Play-Doh diorama of it. Because there's some regular issue right here, any kind of variation of customized gravity would certainly have that issue generate dark-matter-like impacts.