A see-through galaxy questions the need for dark matter

Astronomers baffled by distant galaxy that doesn't have any dark matter

Astronomers perplexed to find that distant galaxy has no dark matter

Recently, the space scientists unveiled a certain ghostly galaxy that is very unusually transparent and is nearly the same size as the Milky Way. The galaxy that is forcing scientists and astrophysicists to ask new questions is called NGC1052-DF2. In spite of the fact that we can't straightforwardly watch it, we know dark matter is there in light of the fact that we can perceive how its gravity influences ordinary matter. Dark matter is a confusing area of astrophysics but it is generally agreed upon that dark matter is a requirement of the existence of galaxies.

First identified with the Dragonfly Telephoto Array (DFA) and later observed by the Sloan Digital Sky Survey (SDSS), the NASA/ESA Hubble Space Telescope, the Gemini Observatory and the Keck Observatory, the galaxy without dark matter stunned scientists. This galaxy has very few numbers of stars but a large chunk of them are amalgamated together in bright clusters. "The stars in the galaxy can account for all of the mass, and there doesn't seem to be any room for dark matter", Van Dokkum said.The team's results demonstrate that dark matter is separable from galaxies."This discovery shows that dark matter is real - it has its own separate existence apart from other components of galaxies", said Van Dokkum. "This result also suggests that there may be more than one way to form a galaxy".

The authors of the research on this ghostly galaxy were initially looking out for a galaxy which is dark matter free; instead, they looked into ultra-diffuse galaxies.

"There's about five times more dark matter in a galaxy than regular matter", explained Dr Michelle Collins, a physicist at the University of Surrey who was not involved in the study. Stars and clusters in the outskirts of galaxies containing dark matter move at least three times faster.

In that study, the researchers found an object that could exist in a universe that has dark matter, but that would be almost unimaginable in a MOND universe: a totally normal galaxy, one that seems to operate without any dark matter-type forces. "So finding the opposite, namely an absence of dark matter, really came out of the blue for us", he said. Imaging them enabled the research study group to establish their activities orbiting the galaxy, which could, consequently, give an action of the quantity of mass that is associated with maintaining the things in position. And 10 objects isn't always enough to accurately measure a galaxy's movement."When more data are obtained, sometimes this [amount] proves to have been enough, but sometimes it proves to have been inadequate". See the distant galaxies behind it?

If there is any dark matter at all, it's very little. Some theories say that dark matter is only an illusion caused by a failure to understand the way gravity works on the grand scale of the universe.

This is highly uncommon for galaxies.

"The hunt is on", van Dokkum said. The next step is to find other galaxies, make the same measurements and see what turns up. That's when they realized that this galaxy was very, very different from other galaxies.

The astronomers measured the speeds of 10 bright globular clusters within the galaxy to calculate how much dark matter there was.

For a galaxy like NGC1052-DF2, you'd expect to see about one hundred times more dark matter than visible matter-but astronomers found it has nearly no dark matter. A lot more typically, exactly how do you create a galaxy without dark issue?

Dr Collins is cautious to conclude that the galaxy has no dark matter halo, based on the current evidence.

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.

DF2 is unique in other ways, too. This would allow the gas to form stars away from clumps of dark matter. "They're much smaller objects", she told BBC News. There's a new idea called emergent gravity that proposes there is no dark matter. "It's like you take a galaxy and also you just have the excellent halo and also globular collections, as well as it in some way neglected to earn whatever else", kept in mind van Dokkum.

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