The newly-developed map of the local Universe is based on the motions of 56,000 galaxies, according to a team of astrophysicists from the Leibniz Institute for Astrophysics Potsdam.
This map shows the distribution of matter in the local Universe; it shows how matter flows, i.e. along which trajectories (thin lines) the galaxies move. Image credit: Valade et al., doi: 10.1038/s41550-024-02370-0.
“Mapping the Universe has always been one of the most challenging tasks in astronomy,” said lead author Dr. Aurelien Valade and colleagues.
“Inaccurate observations, observational errors and incomplete data make this work extremely difficult.”
“In addition, the observed galaxies make up only a small part of the total mass in the Universe, as much of the matter exists in the form of invisible dark matter.”
“Furthermore, galaxies are not bound to be formed in such a way that they accurately trace the underlying matter well, which makes them an uncertain indicator of the matter distribution in the Universe.”
“Therefore, in order to create a map of our cosmic environment, we also look at the motion of galaxies.”
“On the one hand, galaxies move away from us with the expansion of the Universe, but on the other hand they also attract each other due to gravity.”
“These movements can be mapped and reveal the cosmic currents — the rivers and gulf-streams throughout the cosmos on which galaxies move.”
“Since the motion is caused by gravity, it can thus be used to see the invisible.”
To create a map of the local Universe, the authors used data on the motions of 56,000 galaxies from the Cosmic Flows-4 catalogue.
“Since the measurements of each galaxy’s velocity are error prone and fairly uncertain, there are various possible cosmographic maps that would fit the observational data,” they explained.
“Thus, we developed a new approach: a ‘probabilistic’ map of the Universe.”
“Such a map indicates how likely it is that a certain feature, such as a ‘basin of attraction,’ actually exists.”
“A basin of attraction is a region which, absent the cosmic expansion, would collapse to a single point.”
With this new method, the researchers obtained a reliable picture of the large-scale distribution of matter and revealed astonishing structures of our cosmic neighborhood.
“Laniakea, the supercluster to which many believed that our Galaxy belongs, is probably merely an appendage of the much larger Shapley basin. It may not even exist as a separate entity,” they said.
“Even more astonishing is the fact that the Sloan Great Wall — an immense wall composed of hundreds of thousands of galaxies — at around a thousand trillion trillion cubic light years is currently the largest known structure in this cosmic network of galaxies.”
“It is perhaps unsurprising that the further into the cosmos we look, we find that our home supercluster is more connected and more extensive than we thought,” said Dr. Noam Libeskind, co-author on the study.
“Discovering that there is a good chance that we are part of a much larger structure is exciting.”
“At the moment it’s just a hint: more observations will have to be made to confirm the size of our home supercluster.”
The results appear this month in the journal Nature Astronomy.
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A. Valade et al. Identification of basins of attraction in the local Universe. Nat Astron, published September 27, 2024; doi: 10.1038/s41550-024-02370-0
Source : Breaking Science News