Astronomy: The Great Attractor

Wikimedia Commons, CC BY-SA

Commentary

Source: Wikipedia (CC BY-SA)

The Great Attractor The Great Attractor is a region of gravitational attraction in intergalactic space and the a pparent central gravitational point of the Laniakea Supercluster of galaxies that includes the Milky Way galaxy, as well as about 100,000 other galaxies. The observed attraction suggests a localized concentration of mass having the order of 1016 solar masses. However, it is obscured by the Milky Way's galactic plane, lying behind the Zone of Avoidance (ZOA), so that in visible light wavelengths, the Great Attractor is difficult to observe directly.

Commentary

Source: Internal

Why The Great Attractor matters: Cosmology addresses the deepest questions we can ask: where did the universe come from, what is it made of, and what will happen to it in the future? The attraction is observabl e by its effect on the motion of galaxies and their associated clusters over a region of hundreds of millions of light-years across the universe. These galaxies are observable above and below the Zone of Avoidance; all are redshifted in accordance with the Hubble flow, indicating that they are receding relative to the Milky Way and to each other, but the variations in their redshifts are large enough and regular enough to reveal that they are slightly drawn towards the attraction. 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. The Great Attractor itself is moving towards the Shapley Attractor. Thus the Great Attractor, along with the rest of Laniakea, might be part of this larger structure.

Commentary

Source: Internal

Deep dive: The Great Attractor These galaxies are observable above and below the Zone of Avoidance; all are redshifted in accordance with the Hubble flow, indica ting that they are receding relative to the Milky Way and to each other, but the variations in their redshifts are large enough and regular enough to reveal that they are slightly drawn towards the attraction. 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. The Great Attractor itself is moving towards the Shapley Attractor. Thus the Great Attractor, along with the rest of Laniakea, might be part of this larger structure. Source: https://en.wikipedia.org/wiki/Great_Attractor (Wikipedia, CC BY-SA)