Our Galaxy Is Being Pulled Into a ‘Basin of Attraction’
Since the confirmation of its existence in 2014, the Laniakea supercluster was thought to be our ultimate cosmic neighborhood—home to the Virgo supercluster, the local cluster, and the good old Milky Way.
Now, a new study suggests that the Laniakea itself might be part of an even larger structure, known as a basin of attraction.
Understanding these cosmic pockets of matter and their influences on the universe (past and present) will give us better data for exploring questions of dark matter distribution and universal expansion.
The human mind has a tough time comprehending just how big the universe really is. Take, for example, Earth’s cosmic address. We lie, of course, in the Milky Way Galaxy. That is in turn part of the local cluster, the Virgo cluster, and the even larger Virgo supercluster, which stretches 110 million light-years and contains around 110 galaxies and clusters. That means if you wanted to travel across the supercluster at the speed of light, you’d only just now be wrapping up that journey—if you started during the early Cretaceous period.
That’s pretty big, but really, we’re just getting started. With evidence of other, bigger superclusters emerging in the 1980s, scientists discovered an even larger cosmic neighborhood called the Laniakea Supercluster, which contains 100,000 galaxies and has a diameter of roughly 520 million light-years. Now, an international team of researchers reports that even Laniakea is actually part of an even larger “basin of attraction,” or BOA, known as the Shapley Concentration (named after U.S. scientist Harlow Shapley, who first observed this concentration in the 1930s).
Although a perfect name for a space-themed Harlequin romance novel, basins of attraction are actually areas of the universe that contain a concentration of galaxies and clusters, the combined masses of which act as an “attractor.” According to the researchers (following the Lambda Cold Dark Matter model), these basins and structures formed from quantum fluctuations during the early moments of the universe’s rapid expansion. These fluctuations then created galaxies and clusters, which attracted surrounding matter to form cosmic BOAs.
“Our universe is like a giant web,” R. Brent Tully, a co-author of the study from the University of Hawai’i, told Universe Today, “with galaxies lying along filaments and clustering at nodes where gravitational forces pull them together. Just as water flows within watersheds, galaxies flow within cosmic basins of attraction. The discovery of these larger basins could fundamentally change our understanding of cosmic structure.”
Tully’s team measures cosmic flows by studying the movements of distant galaxies, and those movements point to a larger basin (even greater than Laniakea) that is directing those flows. However, the Shapley concentration (which is a staggering ten times the volume of Laniakea) is only half the size of the largest-known structure in space—the Sloan Great Wall. Feeling insignificant yet?
“The dominance of the Sloan Wall basin of attraction over the Shapley basin is truly surprising,” Yehuda Hoffman, a co-author of the study from the Hebrew University of Jerusalem, told The Debrief. “All previous studies, including our own, suggested that Shapley is the main player.”
Because of this detailed view of the Milky Way’s place in the universe, scientists now have a better grasp of the universe’s past, and how the gravitational forces of basins of attraction could impact its evolution going forward.
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