Great Attractor
The Great Attractor is a gravity anomaly in intergalactic space within the range of the Centaurus Supercluster that reveals the existence of a localized concentration of mass equivalent to tens of thousands of Milky Ways, observable by its effect on the motion of galaxies and their associated clusters over a region hundreds of millions of light years across.
These galaxies are all redshifted, indicating that they are receding relative to us and to each other, but the variations in their redshift are sufficient to reveal the existence of the anomaly. The variations in their redshifts are known as peculiar velocities, and cover a range from about +700 km/s to −700 km/s, depending on the angular deviation from the direction to the Great Attractor.
Location
The Great Attractor is situated at a distance of somewhere between 150 and 250 Mly (million light years) (47–79Mpc) from the Milky Way. X-ray observations have revealed that the region of space is dominated by the Norma cluster (ACO 3627), a massive cluster of galaxies, containing a preponderance of large, old galaxies, many of which are colliding with their neighbours, and/or radiating large amounts of radio waves. One theory claims the Great Attractor is a supercluster (possibly the Shapley Supercluster), with Abell 3627 near its center.
The dark flow
- Main article: Dark flow
The dark flow is a velocity tendency of galaxies to move in the direction that was formerly thought to be caused by the Great Attractor, but are now theorized to be outside the observable universe.
