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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 Detect Mysterious Radio Wave Far Away From Milky Way

CHIME is composed of four, 100-meter long half-pipe cylinders of metal mesh, which reconstruct images of the sky by processing the radio signals recorded by more than a thousand antennas.

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Space, astronomers
Part of a 64-dish radio telescope system is seen during an official unveiling ceremony, July 13, 2018, in Carnarvon, South Africa. A Canadian radio telescope has detected repeating radio waves from deep space. VOA

Astronomers in Canada have detected a mysterious volley of radio waves from far outside our galaxy, according to two studies published Wednesday in Nature.

What corner of the universe these powerful waves come from and the forces that produced them remain unknown.

The so-called repeating fast radio bursts were identified during the trial run last summer of a built-for-purpose telescope running at only a fraction of its capacity.

Known by its acronym CHIME, the world’s most powerful radio telescope, spread across an area as big as a football pitch, is poised to detect many more of the enigmatic pulses now that it is fully operational.

“At the end of the year, we may have found 1,000 bursts,” said Deborah Good, a PhD student at the University of British Columbia and one of 50 scientists from five institutions involved in the research.

 

Saraswati, astronomers
Earth is part of the Milky way galaxy. Wikimed

 

High energy bursts

Fast radio bursts (FRBs) flash only for a micro-instant, but can emit as much energy as the sun does in 10,000 years.

Exactly what causes these high-energy surges of long waves at the far end of the electromagnetic spectrum remains the subject of intense debate.

More than 60 bursts have been cataloged since 2007, but only one other, observed in 2012 at the Arecibo Observatory in Puerto Rico, was a repeater.

“FRBs, it seems, are likely generated in dense, turbulent regions of host galaxies,” Shriharsh Tendulkar, a corresponding author for both studies and an astronomer at McGill University, told AFP.

Cosmic convulsions created by the turbulent gas clouds that give rise to stars, or stellar explosions such a supernovae, are both possible incubators.

But consecutive radio bursts are a special case.

Space, Astronomers
The world’s largest single-dish radio telescope at the Arecibo Observatory in Arecibo, Puerto Rico, photographed July 13, 2016. Dwindling funds from the U.S. government and construction of bigger, more powerful telescopes are threatening this telescope’s future. VOA

No little green men

“The fact that the bursts are repeated rules out any cataclysmic models in which the source is destroyed while generating the burst,” Tendulkar added.

“An FRB emitted from a merger of two neutron stars, or a neutron star and a black hole, for example, cannot repeat.”

It is not yet clear whether the breeding grounds of repeating bursts are different from those that produce only a single radio pulse.

Significantly, the 2012 and 2018 “repeaters” have strikingly similar properties.

CHIME (Canadian Hydrogen Intensity Mapping Experiment) also spotted a dozen single burst radio waves, but with an unusual profile.

Most FRBs spotted so far have wavelengths of a few centimeters, but these had intervals of nearly a meter, opening up a whole new line of inquiry for astronomers.

Could these enigmatic radio pulses point to intelligence elsewhere in the Universe? Might they be messages in a bottle?

SpaceX, Astronomers
The night sky is lit up above Vandenberg Air Force Base, California, during the launch of a SpaceX rocket carrying an Argentine Earth-observation satellite. VOA

“It is extremely, extremely unlikely,” Tendulkar said.

“As a scientist I can’t rule it out 100 percent. But intelligent life is not on the minds of any astronomer as a source of these FRBs.”

Constructed in British Columbia, CHIME is composed of four, 100-meter long half-pipe cylinders of metal mesh, which reconstruct images of the sky by processing the radio signals recorded by more than a thousand antennas.

Also Read: Astronauts Would Be Able to Grow Beans in Space in 2021: NASA

“This signal processing system is the largest of any telescope on Earth,” the researchers said in a communique.

The other institutions with leading roles are the University of Toronto, the National Research Council of Canada, and the Perimeter Institute. (VOA)