"The void" is more than a metaphor for gnawing existential pain. In fact, new research from an international team of scientists suggests that a huge void outside our extragalactic neighbourhood could be impacting the way our galaxy — and others around it — move.
Image: NASA/ESA/Hubble Heritage Team
Professor Yehuda Hoffman of The Hebrew University in Jerusalem and his colleagues studied this spooktacular void — called the dipole repeller — that is repelling our Local Group of galaxies away from it. While scientists have long believed that a large, high-density cluster of galaxies called the Shapley Concentration pulls the Milky Way (and others) toward it, this new evidence shows the low-density void is also responsible for shifting galaxies. The authors hypothesise that these two points control the movement of our Local Group of galaxies, hence the name "dipolar". The team's findings were published on January 30 in Nature Astronomy.
The group used the Hubble Telescope among other powerful tools to create 3D models that charted the flow of matter from regions of low to high density. The team was able to confirm that galaxies were in fact floating away from the dipole repeller void and toward the Shapley Concentration.
"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," Prof. Yehuda Hoffman said in a press release. "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."
This new evidence will help scientists understand the direction in which the Milky Way and our neighbouring galaxies are headed as our universe expands. "Future ultra-sensitive surveys at optical, near-infrared and radio wavelengths are required to directly identify the handful of galaxies expected to lie in this void and directly confirm the flow of galaxies away from empty regions and towards regions of high mass concentration," Nature reports.
If you're lost in space, it's good to have a map, I guess.