Until now, it was the edges of Laniakea, our enormous ‘galactic continent’, that marked the maximum distance at which the flow of the ‘rivers of galaxies’ could affect the movements of our Milky Way. But a new map of the region of the Universe around us has just suggested that our galaxy is probably part of an even larger ‘cosmic neighborhood’.
That is the main conclusion of a new study published in ‘Nature Astronomy’ and led by researchers at the Leibniz Institute for Astrophysics in Potsdam and the Institute of Astronomy at the University of Hawaii. In it, researchers, many of whom already participated in the discovery of Laniakea in 2014, now doubt whether Laniakea is really our supercluster of origin, and even wonder if this ‘galactic continent’ really exists.
The Universe in which we live is expanding faster and faster, which means that, in general, all the objects in it are rapidly moving away from each other. But at the same time there are numerous very dense regions, called ‘basins of attraction,’ in which the opposite happens. There, gravity, which tends to bring things together, is stronger than expansion, which tends to separate them, so everything is pulled ‘in’ by the gravitational force of very massive objects, such as large galactic clusters.
Cosmic ‘Matrioskas’
The basins of attraction can be stacked one inside the other like the famous Russian Matryoshkas. Thus, the Moon rotates around the Earth, which in turn rotates around the Sun along with the rest of the planets in the Solar System, which in turn spirals around the central hole of our galaxy.
But the thing doesn’t end there. The next ‘Russian doll’ is the Local Group, which includes the Milky Way, the Andromeda Galaxy and the Triangle Galaxy, along with several dozen smaller satellite galaxies. And after that, the next layers are the Virgo Cluster, which contains about 2,000 galaxies, and the even larger Virgo Supercluster. The last known layer was precisely Laniakea (which means ‘immense sky’ in the Hawaiian language), a supercluster discovered in 2014, which contains around 100,000 galaxies and is approximately 500 million light years in diameter.
In their study, the researchers analyzed the relative motions of more than 56,000 galaxies to create a 3D ‘probabilistic’ map of all the basins of attraction that exist around the Milky Way. Which revealed that there is a good chance that our galaxy is part of a truly enormous basin of attraction, the Shapley Concentration, which has a volume up to 10 times larger than that of Laniakea. Scientists have known for a long time that the Shapley Concentration existed, but they had never thought that it could affect the Milky Way in any way.
Laniakea, an appendage of something larger
On the new map, Laniakea would be nothing more than an appendage of the Shapley Basin, and may not even exist as a separate, independent entity. The map shows numerous basins of attraction spanning billions of light years and spread around the Shapley concentration, including the South Pole Wall, the Boötes Void, and the Perseus-Pisces Supercluster. The largest of them all is the Sloan Great Wall, made up of hundreds of thousands of galaxies and which is around 1.4 billion light years in diameter.
«Perhaps – explains Noam Libeskind, co-author of the study – it is not so surprising that the further we go into the cosmos, the more we realize that our supercluster of origin is more connected and more extensive than we thought. Finding out that there is a lot of possibility for us to be part of a much larger structure is exciting.
The new map includes about 15 basins of attraction. Laniakea would only be an appendage of the Shapley basin, ten times larger
At the moment, researchers believe there is a 60% chance that the Milky Way actually resides in the Shapley Concentration. The uncertainty is largely due to the high error rates that occur when measuring the velocities of distant galaxies, as well as the presence of dark matter between galaxies, which is invisible but can still exert massive gravitational effects in large regions of the planet. space.
In the words of Libeskind, “at the moment it is just a clue: more observations will be necessary to confirm the real size of our supercluster.”
Therefore, researchers will continue to track and map the largest structures in existence, driven by the possibility that our home in the Universe is part of a system much larger and more interconnected than ever imagined.
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