Enormous Extragalactic Void Is Pushing Milky Way Through The Universe

Posted: Jan 31 2017, 12:50pm CST | by , Updated: Jan 31 2017, 12:56pm CST, in News | Latest Science News

 

Enormous Extragalactic Void is Pushing Milky Way Through the Universe
Illustration shows the Shapley Attractor and the Dipole Reppeler. Credit: Hoffman, Pomarede, Tully, Courtois
 

Groundbreaking study reveals that both push and pull are driving our Galaxy’s race through space

Our planet is not static. It is moving at an incredible speed on its axis, across the Universe.

Earth orbits around the sun at about 100,000 kilometer per hour, while our galaxy Milky Way itself moves at roughly 2 million km per hour. But since we all are moving along with it, we can’t feel this rotation or spin.

It has been generally assumed that cosmic dense regions are pulling Milky Way towards the universe, in the same way as gravity makes Newton’s apple fall to Earth. Initially, the Great Attractor, a gravitational anomaly that is populated with clusters of galaxies was held responsible for the motion. Then, Shapley Concentration, an area which lies 600 million lightyears beyond the Great Attractor was considered the prime suspect in the process.

But now scientists have discovered another reason why Milky Way is racing through the universe.  According to new groundbreaking report, our galaxy is not only being pushed, but also pulled. And the driving force behind this motion is a very large empty region located in our extragalactic neighborhood. This newly discovered void itself is devoid of galaxies but it exerts enormous force on our Local Group of galaxies and pushes them through the space.

The presence of this previously unknown intergalactic void had been hinted at in previous studies but it was never confirmed due to lack of solid evidence.  In this new effort, the team, led by Yehuda Hoffman from Hebrew University alongside colleagues in the USA and France, tested a new approach. Instead of finding the positions of galaxies, researchers focused their attention on galaxy motions. 

Using data from powerful telescopes like Hubble, they constructed a 3-D map of the galaxy flow field. Flow-field considers the density and velocity of a fluid over space and time and uses this to infer the underlying mass distribution.

The method allowed researchers to uncover the mysterious void that was lurking in the universe. It has been dubbed Dipole Repeller. 

“By 3-d mapping the flow of galaxies through space, we found that our Milky Way galaxy is speeding away from a large, previously unidentified region of low density. Because it repels rather than attracts, we call this region the Dipole Repeller,” said Hoffman. “In addition to being pulled towards the known Shapley Concentration, we are also being pushed away from the newly discovered Dipole Repeller. Thus it has become apparent that push and pull are of comparable importance at our location.”

The landmark discovery also enabled researchers to explain both the direction of the Milky Way's motion and its velocity relative to the rest of the Universe. Researchers believe further studies will expand their understanding of the void and its underlying features.

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Hira Bashir covers daily affairs around the world.

 

 

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