A galaxy without dark matter


A galaxy without dark matter

Astronomers first discovered the galaxy in 2000 as a smudge on old photographic plates. It is located about 65 million light-years away in the constellation of Cetus.

"If there is no dark matter in this galaxy, it will be minimal". But DF2 may as well be called F-U, because that's what it's saying to scientists who thought they understood galaxies, dark matter, and really anything about our universe. NGC1052-DF2 was discovered while scientists were searching for large, ultra-diffuse galaxies to study.

"How did we get a gas cloud of that size that was able to form a galaxy, that was able to have enough gravity?" says Risa Wechsler, an astronomer at Stanford University who was not involved in the new research.

"It challenges the standard ideas of how we think galaxies work", said Dokkum. NGC1052-DF2 isn't just missing dark matter it also only has about one star for every 200 found in the Milky Way. From the W.M. Keck Observatory, they measured the velocity of clusters of stars (called globular clusters) within DF2 and found they were moving slower than expected. More generally, how do you form a galaxy without dark matter?

"Finding a galaxy without dark matter is unexpected, because this invisible, mysterious substance is the most dominant aspect of any galaxy", said lead study author Pieter van Dokkum, from Yale University. Thus, it is being speculated that the formation of this particular galaxy ought to be very different from the formation of the other galaxies that consist dark matter.

Paradoxically, by finding a galaxy with little-to-no dark matter, it further suggests that dark matter does in fact exist.

The team's results will appear in the March 29, 2018, issue of the journal Nature. In fact, the research team had previously looked at galaxies of the same class as NGC1052-DF2 and found they were made up nearly entirely of dark matter. By following the movement of 10 inserted star clusters, the group could decide how much mass is tucked into the system.

Scientists have various theories on how this galaxy came to be. If dark matter only served to explain the effect of the gravity from regular matter, it should still be visible in NGC1052-DF2. Perhaps it formed from the gas flung out as two other galaxies merged.

"The hunt is on", van Dokkum said.

Gemini then assisted by showing the galaxy was not interacting with other galaxies. With measurements from the telescopes, van Dokkum and colleagues calculated how fast those clusters moved.

Despite how little we know about dark matter, we can tell when it's there, from the way it impacts galaxies and causes odd movements that don't fit the laws of gravity. Utilizing the quantity of light given off by the galaxy created a quote of the overall mass of celebrities in the galaxy that was likewise in the neighborhood of 108. Indeed, if the mass of DF2 is equal to the sum of the masses of its stars, gas, and dust, it's because it contains no or nearly no dark matter! Some physicists have postulated that there is no such thing as dark matter, however, and that what we perceive as giant, starlight-bending clumps of heavy, invisible material is actually something else that is profoundly misunderstood.

More work has to be done by the team which is conducting this research and after that, the actual occurrence of the galaxy and the non-occurrence of the dark matter will be proved.

Each of these would certainly have to be analyzed in information to identify if it can develop the distinctive attributes of NGC1052- DF2.

"It's sort of non-negotiable", said van Dokkum of the baffling conclusion, which is being taken seriously by other scientists working in the field.



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