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Mysterious Galaxy signal comes from the past, not dark matter

An artistic illustration of the milky way Galaxy with a bulge of old stars in the core

(L Jaramillo and O pierre macias, Virginia Tech)

A mysterious cosmic signal radiates from the center of our milky way Galaxy is actually caused by old stars, rather than dark matter, according to a new study.

There is a mysterious abundance of high-energy gamma-rays in the Milky way’s core, also known as the galactic bulge. Previous studies suggested that this abundance is born from the dark matter — the mysterious, invisible substance that does not emit light or energy, but it is thought to be the largest part of the matter in the universe.

Instead, new research shows that the gamma-rays originate from thousands of fast rotating neutron stars known as millisecond pulsars, which are believed to be about 10 billion years old. Because the stars are so far away, their emissions appeared to merge into a signal that astronomers had previously interpreted as dark matter, according to a statement from the Australian National University (ANU). [Our milky way Galaxy’s Core Revealed (Photos)]

“On the distance to the center of our galaxy, the emission of many thousands of these swirling, dense stars could mix together to imitate smoothly divided signal that we expect from dark matter,” Roland Crocker, co-author of the study and a researcher from the ANU Research School of Astronomy and Astrophysics, said in the statement.

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Although dark matter cannot be directly observed, it is thought to be made of weakly interacting massive particles (Wimps). These particles may occasionally crash into each other and rays, that is a billion times more energy than visible light. That is the reason why astronomers previously thought that gamma rays-the highest energy light in the universe — to be found in the centre of the milky way Galaxy originated from dark matter, the researchers said.

Using data from the Fermi Gamma-ray Space Telescope, which have been orbiting the Earth since 2008, the researchers found that the milky way Galaxy in the gamma-ray signals mirror the distribution of the stars in the center of the milky way. This data further supports the idea that the gamma-rays come from old stars, instead of dark matter, the study said. [The Search for Dark Matter in Photos]

A mysterious cosmic signal radiates from the center of our milky way Galaxy is actually caused by old stars, rather than dark matter, according to a new study.

There is a mysterious abundance of high-energy gamma-rays in the Milky way’s core, also known as the galactic bulge. Previous studies suggested that this abundance is born from the dark matter — the mysterious, invisible substance that does not emit light or energy, but it is thought to be the largest part of the matter in the universe.

Instead, new research shows that the gamma-rays originate from thousands of fast rotating neutron stars known as millisecond pulsars, which are believed to be about 10 billion years old. Because the stars are so far away, their emissions appeared to merge into a signal that astronomers had previously interpreted as dark matter, according to a statement from the Australian National University (ANU). [Our milky way Galaxy’s Core Revealed (Photos)]

 

“On the distance to the center of our galaxy, the emission of many thousands of these swirling, dense stars could mix together to imitate smoothly divided signal that we expect from dark matter,” Roland Crocker, co-author of the study and a researcher from the ANU Research School of Astronomy and Astrophysics, said in the statement.

Although dark matter cannot be directly observed, it is thought to be made of weakly interacting massive particles (Wimps). These particles may occasionally crash into each other and rays, that is a billion times more energy than visible light. That is the reason why astronomers previously thought that gamma rays-the highest energy light in the universe — to be found in the centre of the milky way Galaxy originated from dark matter, the researchers said.

Using data from the Fermi Gamma-ray Space Telescope, which have been orbiting the Earth since 2008, the researchers found that the milky way Galaxy in the gamma-ray signals mirror the distribution of the stars in the center of the milky way. This data further supports the idea that the gamma-rays come from old stars, instead of dark matter, the study said. [The Search for Dark Matter in Photos]

 

 

 

 

 

 

 

 

 

“While the center of our galaxy may be rich in dark matter, it is also populated by old stars that there is a structure called the galactic bulge,” Crocker said in the statement.

“Current observational and theoretical work is underway to verify or refute the hypothesis that the gamma-ray signal comes from millisecond pulsars,” Croker added. However, “millisecond pulsars close to the Earth are known to be gamma-ray emitters.”

The findings were published March 12 in the journal Nature Astronomy.

Original article on Space.com.

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