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Ghostly galaxy without dark matter stuns astronomers

To find an explanation, the team is already hunting for more dark-matter deficient galaxies as they analyse Hubble images of 23 ultra-diffuse galaxies

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UFO religion as a concept is now becoming a part of popular understanding.
Countless galaxies exist in the universe, each hiding secrets that humankind is yet to unearth. Pixabay
  • Astronomers discovered galaxy missing its dark matter
  • Dark matter is believed to be integral to any galaxy
  • It is the glue which holds everything together

In a shocking discovery, astronomers have found a galaxy that is missing most — if not all — of its dark matter. This discovery of the galaxy NGC 1052-DF2, detailed in the journal Nature, challenges currently-accepted theories of and galaxy formation and provides new insights into the nature of dark matter.

Black hole in milky way
Astronomers discovered a galaxy missing its dark matter. VOA

“Dark matter is conventionally believed to be an integral part of all galaxies — the glue that holds them together and the underlying scaffolding upon which they are built,” explained study co-author Allison Merritt from Yale University in the US and the Max Planck Institute for Astronomy, Germany.

“This invisible, mysterious substance is by far the most dominant aspect of any galaxy. Finding a galaxy without any is completely unexpected; it challenges standard ideas of how galaxies work,” said lead researcher Pieter van Dokkum of Yale University. “There is no theory that predicts these types of galaxies — how you actually go about forming one of these things is completely unknown,” Merritt said.

For the study, the researchers used the NASA/European Space Agency’s Hubble Space Telescope and several other observatories. Hubble helped to accurately confirm the distance of NGC 1052-DF2 to be 65 million light-years and determined its size and brightness.

Saraswati
Dark matter is the glue which holds everything together in a galaxy. Wikimedia

Based on these data the team discovered that the newly discovered galaxy is larger than the Milky Way, but contains about 250 times fewer stars, leading it to be classified as an ultra diffuse galaxy. “I spent an hour just staring at this image,” van Dokkum said as he recalled first seeing the Hubble image of NGC 1052-DF2.

“This thing is astonishing: a gigantic blob so sparse that you see the galaxies behind it. It is literally a see-through galaxy,” he added. Further measurements of the dynamical properties of 10 globular clusters orbiting the galaxy allowed the team to infer an independent value of the galaxies mass.

This mass is comparable to the mass of the stars in the galaxy, leading to the conclusion that NGC 1052-DF2 contains at least 400 times less dark matter than astronomers predict for a galaxy of its mass, and possibly none at all.

Also Read: Milky Way’s neighbouring galaxy is of same size, not bigger

This discovery is unpredicted by current theories on the distribution of dark matter and its influence on galaxy formation. The discovery of NGC 1052-DF2 demonstrates that dark matter is somehow separable from galaxies. This is only expected if dark matter is bound to ordinary matter through nothing but gravity.

Cosmic rays
Dark matter is integral to all galaxies. Pixabay

Meanwhile, the researchers already have some ideas about how to explain the missing dark matter in NGC 1052-DF2. Did a cataclysmic event such as the birth of a multitude of massive stars sweep out all the gas and dark matter? Or did the growth of the nearby massive elliptical galaxy NGC 1052 billions of years ago play a role in NGC 1052-DF2’s dark matter deficiency?

These ideas, however, still do not explain how this galaxy formed. To find an explanation, the team is already hunting for more dark-matter deficient galaxies as they analyse Hubble images of 23 ultra-diffuse galaxies — three of which appear to be similar to NGC 1052-DF2. IANS

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Astronomers Use Massive Cluster of Galaxies as X-Ray Magnifying Glass to Spot Tiny Dwarf Galaxy

What they detected appears to be a blue speck of an infant galaxy, about 1/10,000 the size of our Milky Way, in the midst of churning out

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Astronomers, Galaxies, X-Ray
While galaxy clusters have been used to magnify objects at optical wavelengths, this is the first time scientists have leveraged these massive gravitational giants to zoom in on extreme, distant, X-ray-emitting phenomena. Pixabay

Using a massive cluster of galaxies as an X-ray magnifying glass, astronomers have spotted a tiny dwarf galaxy in the first, super-energetic stages of star formation.

The new lens technique allowed the astronomers to peer back in time, to nearly 9.4 billion years ago.

While galaxy clusters have been used to magnify objects at optical wavelengths, this is the first time scientists have leveraged these massive gravitational giants to zoom in on extreme, distant, X-ray-emitting phenomena.

What they detected appears to be a blue speck of an infant galaxy, about 1/10,000 the size of our Milky Way, in the midst of churning out its first stars — supermassive, cosmically short-lived objects that emit high-energy X-rays, which the researchers detected in the form of a bright blue arc.

Astronomers, Galaxies, X-Ray
The new lens technique allowed the astronomers to peer back in time, to nearly 9.4 billion years ago. Pixabay

“It’s this little blue smudge, meaning it’s a very small galaxy that contains a lot of super-hot, very massive young stars that formed recently,” said Matthew Bayliss, a research scientist in Massachusetts Institute of Technology’s Kavli Institute for Astrophysics and Space Research.

“This galaxy is similar to the very first galaxies that formed in the universe … the kind of which no one has ever seen in X-ray in the distant universe before.”

The detection of this single, distant galaxy is proof that scientists can use galaxy clusters as natural X-ray magnifiers, to pick out extreme, highly energetic phenomena in the universe’s early history, Bayliss said.

“With this technique, we could, in the future, zoom in on a distant galaxy and age-date different parts of it — to say, this part has stars that formed 200 million years ago, versus another part that formed 50 million years ago, and pick them apart in a way you cannot otherwise do,” said Bayliss.

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The findings have been published in the journal Nature Astronomy. (IANS)