Blog Space 04 September 2014

A better map of our cosmic neighbourhood


A SLICE OF THE LANIAKEA SUPERCLUSTER WITH COLOURS REPRESENTING DENSITY – RED FOR HIGH DENSITIES AND BLUE FOR VOIDS – AREAS WITH RELATIVELY LITTLE MATTER. INDIVIDUAL GALAXIES ARE SHOWN AS WHITE DOTS. VELOCITY FLOW STREAMS WITHIN THE REGION GRAVITATIONALLY ARE SHOWN AS WHITE THREADS. THIS REGION CONTAINS THE MASS OF 100 MILLION BILLION SUNS. THE MILKY WAY IS MARKED BY THE BLACK DOT IN THE CENTRE OF THE IMAGE.
SDVISION INTERACTIVE VISUALIZATION SOFTWARE BY DP AT CEA/SACLAY, FRANCE

Astronomers have drawn a detailed map of our immediate cosmic neighbourhood – an immense supercluster of galaxies containing the Milky Way.

They have named it "Laniakea," meaning "immense heaven" in Hawaiian.

University of Hawaii at Manoa astronomer R. Brent Tully led the international team which explains its work in Nature this month.

Galaxies are not distributed randomly throughout the universe but in groups that contain dozens of galaxies, and in massive clusters containing hundreds of galaxies, all interconnected in a web of filaments in which galaxies are strung like pearls.

Where these filaments intersect, the astronomers say, we find huge structures, called "superclusters". These structures are interconnected, but they have poorly defined boundaries.

A galaxy lying between two of these structures will be caught in a gravitational tug-of-war in which the balance of the gravitational forces from the surrounding large-scale structures determines the galaxy's motion.

By mapping the velocities of galaxies throughout our local universe, the team was able to define the region of space where each supercluster dominates.

The Milky Way lies on the outskirts of the Laniakea Supercluster, which is 500 million light-years in diameter and contains the mass of 10^17 Suns in 100,000 galaxies.

There is a video giving a feel for the structure of our home supercluster and of galaxies and how they move in the nearby universe here.

Two views of the Laniakea Supercluster. The outer surface shows the region dominated by Laniakea’s gravity. The streamlines shown in black trace the paths along which galaxies flow as they are pulled closer inside the supercluster. Individual galaxies’ colours distinguish major components within the Laniakea Supercluster.
SDvision interactive visualization software by DP at CEA/Saclay, France

  1. http://www.nature.com/news/earth-s-new-address-solar-system-milky-way-laniakea-1.15819
  2. http://vimeo.com/104704518
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