A massive void outside our extragalactic community could be affecting the way the Milky Way as well as other galaxies move, a new study from an international team of researchers reveals.
The new research, suggesting that our galaxy is being both pushed and pulled, studied the huge void, called the Dipole Repeller, that is responsible for repelling our Local Group of galaxies.
Push And Pull Through The Universe
Scientists previously assumed that the Great Attractor, a neighborhood of a half-dozen rich clusters of galaxies situated 150 million light-years from the Milky Way, is pulling our galaxy toward it. They then focused on another area of more than two dozen clusters, this time called the Shapley Concentration, sitting 600 million light-years beyond the Great Attractor.
The new evidence points to the void as the likely key for shifting galaxies, with the authors hypothesizing that the two points are controlling the group of galaxies’ movement, hence the term “dipolar.”
"By 3D-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,” explained lead researcher and professor Yehuda Hoffman in a statement. “Because it repels rather than attracts, we call this region the Dipole Repeller.”
Apart from being pulled toward the Shapley Concentration, our galaxy is also being repelled from the Dipole Repeller — the pushing and pulling serving as key in the Milky Way’s location, he added.
As The Universe Expands
The original force behind the motion of galaxies is the Big Bang explosion, but some galaxies move faster or slower now than such impetus from the groundbreaking event occurring more than 14 billion years ago.
We live in an expanding universe, Hoffman told Haaretz, and if there is uniform density there would be nothing that can lead a galaxy to deviate from its original trajectory and speed.
With respect to the remainder of the universe, the Milky Way is moving at around 630 kilometers per second, or about 2.3 million kilometers per hour (1.4 million miles per hour). This motion has always puzzled researchers since it was discovered four decades earlier.
The scientists used the Hubble Space Telescope to construct a three-dimensional map charting the flow of matter from low- to high-density regions. From there they confirmed the push and pull occurring in the great wide galactic neighborhood.
Through the new scientific evidence, scientists will be able to better analyze the direction in which the Milky Way as well as its neighboring galaxies are heading toward as the universe continues to expand. Future inquiries using ultra-sensitive tools at varying wavelengths are expected to directly see the galaxies lying in this void.
The findings are discussed in the journal Nature Astronomy.
In related news, the universe is found to grow at a faster pace than scientists have previously thought, with the Hubble constant now upgraded to 44.7 miles per second per megaparsec by a team of astronomers. The new number was derived by a team of scientists from the Max Planck Institute for Astrophysics in Germany and the école Polytechnique Fédérale de Lausanne in Switzerland.