Researchers have been working out the gravitational structure in our universe for years. Based on Gerard de Vaucouleurs’s work in the 1950s, astrophysicists have thought of our galaxy as being on the edge of what is called, Local Supercluster, a structure about 100 million light-years wide.
But astronomers have also seen even larger structures in the universe, on the scale of several hundred million light-years, thanks to the Sloan Digital Sky Survey and other work.
Brent Tully (University of Hawaii, Honolulu) and his colleagues have engaged in quite a different approach. The team used galaxies’ peculiar velocities, which are the galaxies’ motions due to the local gravitational landscape. Galaxies fall to or from one another in this landscape, the Milky Way, and many others seem to be moving toward what’s called the Great Attractor, a dense region in the vicinity of the Centaurus, Norma, and Hydra clusters about 160 million light-years away.
Unusual velocities are on the order of a few hundred kilometers per second, whereas the cosmic expansion velocities rise to 10,000 km/s roughly 130 million light-years away. Tully believes that there’s about 10-20% ambiguity in the peculiar velocity measurement for an individual galaxy.
But the team found a method to avoide this set back, by using an analysis technique called Wiener filtering. This algorithm made it possible for the team to basically take a step back and look at the big picture, revealing the large-scale flow patterns created by galaxies’ motions. With this wide-field view, the individual uncertainties are have no effect.
Carlisle, Casmille M. "Laniakea: Our Home Supercluster." Sky and Telescope.
N.p., 3 Sept. 2014. Web. 21 Sept. 2014.