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Most Complete 3-D Map Of Local Universe Unveiled By Astronomers
Wednesday, May 25, 2011 20:51
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Most complete 3D Map of the Local Universe
Credit: University of Portsmouth
Astronomers have unveiled the most complete 3-D map of the local universe ever created – to a distance of 380 million light-years. Taking more than 10 years to complete, the 2MASS Redshift Survey (2MRS) extends closer than previous surveys to the Galactic plane – a region that is generally obscured by dust.
The survey has mapped in detail areas previously hidden behind our Milky Way to better understand the impact they have on its motion in relation to the rest of the universe. This has been a puzzle ever since astronomers were first able to measure it and found it couldn’t be explained by the gravitational attraction from any visible matter. Massive local structures, like the Hydra-Centaurus region (the "Great Attractor") were previously hidden almost behind the Milky Way but are now shown in great detail by 2MRS.
Karen Masters, from the Institute of Cosmology and Gravitation, presented the new map today in a press conference at the 218th meeting of the American Astronomical Society in the Harvard-Smithsonian Center for Astrophysics (CfA) USA.
She said: "The 2MASS Redshift Survey is a wonderfully complete new look at the local universe – particularly near the Galactic plane. A galaxy's light is 'redshifted' or stretched to longer wavelengths by the expansion of the universe. The farther the galaxy, the greater its redshift, so redshift measurements yield galaxy distances. It’s the vital third dimension in a 3-D map and will enable cosmologists to study the area in much more detail."
Astronomers chose galaxies to map from images made by the Two-Micron All-SkySurvey (2MASS). This survey scanned the entire sky in three near-infrared wavelength bands. Near-infrared light penetrates intervening dust better than visible light, allowing astronomers to see more of the sky. But without adding redshifts, 2MASS makes only a 2-D image.
Some of the galaxies mapped had previously-measured redshifts, and Huchra started painstakingly measuring redshifts for the others in the late 1990s using mainly two telescopes: one at the Fred Lawrence Whipple Observatory on Mt. Hopkins, AZ, and one at the Cerro Tololo Inter-American Observatory in Chile. The last observations were completed by 2MRS observers on these telescopes in October 2010.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
Source: University of Portsmouth
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