Galaxies aren’t spread evenly throughout space. They exist in groups, clusters, and superclusters. Our own Milky Way galaxy exists in an impossibly vast structure called the Laniakea supercluster. Laniakea was defined in 2014, and it contains over 100,000 galaxies.
Now a team of astronomers have discovered another immense feature beyond Laniakea, called the South Pole Wall.
The South Pole Wall is like an arm wrapping around the Laniakea supercluster. The name is inspired by the Earth’s south pole. In that direction, the wall is at its thickest.
The Wall arches in a great semi-circle covering 200 degrees and reaching well into the northern sky. The concentration in the direction of the south pole is 500 million light years away, and the Wall’s extended arm to the north is 300 million light years away.
“We have found it thanks to its gravitational influence, imprinted in the velocities of a sample of galaxies.”
Daniel Pomarède, Cosmic Cartographer, and staff scientist, Institute of Research into the Fundamental Laws of the Universe.
A team of astronomers have spent a decade mapping the South Pole Wall. For such a large structure, the South Pole Wall has gone unnoticed for quite some time. This is due to its location in a region of the sky that has not been completely surveyed, and where direct observations are hindered by foreground patches of galactic dust and clouds.
Astronomers have also mapped out other massive features, like the Shapley Supercluster and the Great Attractor, which is the central gravitational point of the Laniakea Supercluster.
R. Brent Tully, Study Co-Author, adds: “The galaxies in the arm aren’t static. There’s lots of movement. They move along the arm to the South Pole. From there, they move through a region obscured from our view by the Milky Way. Then, they move toward the Shapley connection, the largest structure in our neighbourhood of the Universe.”
The researchers aren’t certain if what they’ve mapped so far is the entirety of the South Pole Wall. “We wonder if the South Pole Wall is much bigger than what we see,” said co-author R. Brent Tully. “What we have mapped stretches across the full domain of the region we have surveyed. We are early explorers of the cosmos, extending our maps into unknown territory,” Tully said.