A team led by an Israeli astrophysicist has discovered a void in the universe which is responsible for pushing our Milky Way galaxy through space at immense speed.
It has long been known that a supercluster of galaxies, known as the Shapley Concentration, is pulling the Milky Way towards it, but for years scientists have suspected that another force was also contributing to the Milky Way’s velocity. Now, Professor Yehuda Hoffman and his team at Hebrew University have identified a void they call the Dipole Repeller, which is almost entirely empty of galaxies, meaning it has the effect of repelling the Milky Way.
“We approached the problem in a different way,” explained Professor Hoffman. “Rather than looking at the distribution of the galaxies we looked at a sample of about 8,000 galaxies and measured their velocity which is a very challenging task.”
The team was able to construct a 3D map showing how nearby galaxies flow away from the Dipole Repeller and towards the Shapley Concentration.
Through this process the team of Israeli, French and American astrophysicists, established the existence of the Dipole Repeller. They concluded that the Shapley Concentration and the Dipole Repeller are working in conjunction to create the speed of 630 kilometers per second, (1.4 million miles per hour) at which the Milky Way is travelling.
“The novelty is that we completed the picture,” said Professor Hoffman. “We showed the push in addition to the pull and that they are working equally to create our motion.”
Professor Hoffman said work of this kind allowed scientists to travel back into the past and then simulate the evolution of the universe from the past to the present. “This is akin to experimenting with the formation of the universe on the computer,” he explained.
The research was originally published in the journal Nature Astronomy.