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New galaxy discovered that's light on dark matter

The galaxy NGC 1052-DF2 has been found to have very little dark matter
The galaxy NGC 1052-DF2 has been found to have very little dark matter
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The galaxy NGC 1052-DF2 has been found to have very little dark matter
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The galaxy NGC 1052-DF2 has been found to have very little dark matter

Some of the strongest evidence for dark matter to date has been discovered – and ironically, that's thanks to its absence. In a pair of studies published this week, astronomers have shed new light on dark matter through close observation of a galaxy previously found to have very little of the stuff, while the same team found a new example of a similar oddball galaxy.

The idea that the universe is full of mysterious, invisible matter first arose in 1933. Swiss astrophysicist Fritz Zwicky noticed that a cluster of galaxies was moving faster than should be possible, based on the mass of the visible matter in them. He calculated that there had to be far more mass in the cluster than they could see, and the concept of dark matter was born.

In the decades since then, dark matter has all but been confirmed indirectly, although the actual particles themselves still elude direct detection. Last year a Yale University team discovered one of the most compelling clues to date: a galaxy with almost no dark matter at all.

It's generally believed that galaxies are held together through the gravitational influence of clumps of dark matter, so to find a galaxy with little to no dark matter was a surprise. And while it might sound like a strike against the theory, it actually ends up supporting it.

Dark matter was "invented" to plug a hole between calculations and observations, and some argue that it's our understanding of the laws of physics that needs a revision instead. But if that were the case, then this same discrepancy should apply to every galaxy. Finding a galaxy that's light on dark matter shows that it is a separate substance that can vary in amount, rather than a mathematical mistake.

Now, two new studies have backed up the earlier work. In the first, astronomers took a closer look at the galaxy, known as NGC 1052-DF2 (or DF2 for short), and clocked the speed of its stars. Sure enough, the galaxy is moving at roughly 6.5 million km/h (4 million mph), which is consistent with the expected speed based on the mass of its visible matter. If the galaxy had the usual amounts of dark matter, it would be moving much faster.

The second study found that DF2 isn't a unique anomaly. Some of the scientists behind the discovery of the first dark matter-deprived galaxy have now found a second example, dubbed DF4. This galaxy has a similar size, shape and surface brightness as the first – and of course, a similarly-slow speed for the movement of its stars.

"Discovering a second galaxy with very little to no dark matter is just as exciting as the initial discovery of DF2," says Pieter van Dokkum, an author of both studies. "This means the chances of finding more of these galaxies are now higher than we previously thought. Since we have no good ideas for how these galaxies are formed, I hope these discoveries will encourage more scientists to work on this puzzle."

The researchers plan to continue scanning the sky for more examples using the Dragonfly Telephoto Array. Once candidates have been identified, they can be studied in closer detail by telescopes at the Keck Observatory.

Both studies were published in The Astrophysical Journal.

Source: Yale University

7 comments
mpc755
Dark matter is a supersolid that fills 'empty' space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity. The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do. Displaced supersolid dark matter is curved spacetime. The reason for the mistaken notion the galaxy is missing dark matter is that the galaxy is so diffuse that it doesn't displace the supersolid dark matter outward and away from it to the degree that the dark matter is able to push back and cause the stars far away from the galactic center to speed up. It's not that there is no dark matter connected to and neighboring the visible matter. It's that the galaxy has not coalesced enough to displace the supersolid dark matter to such an extent that it forms a halo around the galaxy. A galaxy's halo is not a clump of dark matter traveling with the galaxy. A galaxy's halo is displaced supersolid dark matter.
Cryptonoetic
Hello 'mpc755', May I trouble you to expand further on how spacetime, curved by dark matter, "pushes back" on a galaxy? Would I be correct in inferring that you are referring to 'negative' gravity? Thanks.
ProfessorWhat
... . . . "it's absence"??? how can there be an absence of something that clearly doesn't exist no matter how many billions we pour into looking for dark matter/energy!!
Daniel Gregory
Quantum Inertia elegantly fills the holes in the bad math that lead to the creation of "dark matter" theories. Not only does it remove the need for Dark Matter in explaining the motion of galaxies, but it's also something that we can test and see the immediate effects of. It also explains why something like a resonance engine works rather than people throwing their arms up in the air saying it "breaks the laws of thermodynamics". Because we've built one and it works. No dark matter required.
Jerome Morley Larson Sr eAIA
Dark matter is time; time is the force that expands logorithmically, quantum inertia is the result of time spinnng the atom causing centrifugal force that expands — the differential expansion of large mass like Earth compared to the stuff upon it is the inertial energy we call gravity — proof is that all objects “fall” to earth at the same speed, instantly starting and constantly accelerating — the time dark matter of space acts upon each object in space from all directions, causing a shadow of less force between objects which becomes stronger as they near each other, causing an attraction which we also call gravity. Time itself varies in frequency depending upon the medium, causing differential expansion that enhances/depresses other causes; perhaps time is infinitely variable as Einstein postulated, relating it to speed; which is the same thing.
kurt12
for years I have talked about this - gravity gets stronger as it travels there is not any dark matter - all forces get stronger as they travel - magnetic fields of galaxies are a lot like gravity of galaxies - magnetic fields decrease less fast than 1/rr through a galaxy - magnetic fields decrease less fast than 1/rr between galaxies - far from a cluster of galaxies magnetic fields are extreme strong Kurt sStocklmeir
Paul Muad'Dib
Dark matter strongly interacts with ordinary matter? You should google that professor mpc755.