Our home, the Milky Way, doesn’t seem particularly strange for a galaxy. Medium-sized, spiral-shaped, with a few twists, indicates a destructive past. But astronomers have discovered an oddity not seen in any galaxy they’ve ever studied: The Milky Way is too big for its surroundings. In particular, it appears too large for the area known as the local page it resides in. This flattened arrangement of galaxies has similar velocities, bounded on either side by relatively empty space called space.

Our Local Sheet separates the Local Gap in one direction from the South Gap in the other, as an example of a “cosmological wall”. Relationships between galaxies on the Local Page seem to strongly influence their behavior; For example, their velocities are equal with respect to the expansion of the universe. Outside of the cosmological wall environment, these velocities would have a much wider range.

To determine the impact of our environment on the galaxies around us, a team of astronomers led by Miguel Aragon of the National Autonomous University of Mexico performed an analysis using simulations from the IllustrisTNG project, which models the physical universe.

They did not expect to find anything out of the ordinary.

“The Milky Way is special in a way,” says Aragon. “Earth is undoubtedly special, the only home of life as we know it. But it is not the center of the universe, or even the solar system. And the Sun is just an ordinary star among billions of stars in the Milky Way. Even our own galaxy was just another spiral galaxy among the billions of galaxies in the observable universe. ”

But when they modeled a volume of space about a billion light-years across containing millions of galaxies, a different picture emerged: Only a handful of galaxies as large as the Milky Way could be contained within the wall’s cosmological structure.

“The Milky Way has no particular mass or type. There are many spiral galaxies roughly similar to it,” says astronomer Joe Silk of the Institute for Astrophysics at the Sorbonne University in Paris, France.

“But considering its surroundings, that’s very rare. If you could easily see the nearest dozen or so large galaxies in the sky, you’d see that they’re all located almost in a ring embedded in the local layer. That’s not so much. It’s something special in itself. “It’s very rare that they have a galaxy as large as the Milky Way inside their galactic walls.”

The team’s analysis did not take into account Andromeda, the Milky Way’s largest galactic neighbor. Also a feature of the Local Page – and thus part of the same cosmological wall – is a galaxy the size of the Milky Way. Their conclusions still hold, as it would be even rarer to have two heavyweights on a cosmological wall.

However, the study highlights that when studying the Milky Way, we may need to consider our local environment rather than assuming that our home is usually in the middle of the universe.

Future studies may consider more galaxies within the Local Group, as the team’s simulations only consider the context of the Milky Way inside the cosmological wall. The researchers also note that the environmental context may help explain some previously unexplained phenomena, such as the unusual arrangement of satellite galaxies around Andromeda and the strange absence around the Milky Way.

“One should be careful when choosing properties that are considered ‘private’,” says astronomer Marc Neyrink of the Basque Science Foundation in Spain.

“If we put an absurd constraint on a galaxy such that it should include the article we wrote about it, we would certainly be the only galaxy in the observable universe. But we think this galaxy is “too big for a wall.” “