An international group of astronomers, including Lucas Macri of Texas A&M University, has unveiled the most complete 3-D map of the local Universe to great worldwide fanfare.
Macri, assistant professor of physics and astronomy and a member of Texas A&M’s George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, is one of the leading members of the team that created the map, which contains galaxies as far as a billion light-years. Known as the 2MASS Redshift Survey (2MRS), it is the result of a decade-long effort initiated by an astronomical legend, the late Dr. John Huchra, a longtime astronomer at the Harvard-Smithsonian Center for Astrophysics.
Karen Masters (University of Portsmouth, United Kingdom) presented the new map in a Wednesday (May 26) press conference at the 218th meeting of the American Astronomical Society, crediting Huchra for his masterpiece.
“The 2MASS Redshift Survey is a wonderfully complete new look at the local Universe, particularly near the Galactic plane [a region generally obscured by dust],” Masters said. “We’re also honoring the legacy of the late John Huchra, who was the leader and guiding force behind this and earlier galaxy redshift surveys.”
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 — the vital third dimension in a 3-D map.
The 2MRS team chose 45,000 galaxies based on images made by the 2 Micron All-Sky Survey (2MASS). This survey scanned the entire sky in three near-infrared wavelength bands. Near-infrared light, which Macri notes we feel as heat, penetrates intervening dust better than visible light, allowing astronomers to see more of the sky. The dust can be thought of as cosmic smoke, and observing in the near-infrared allows us to clear away the smoke to see the Universe clearly.
However, without adding redshifts, 2MASS makes only a 2-D image. Many of the galaxies mapped had previously-measured redshifts, but 11,000 new ones were measured by Huchra, Macri and collaborators starting in the late 1990s using mainly two telescopes: one at the Fred Lawrence Whipple Observatory on Mount Hopkins, Ariz., and one at the Cerro Tololo Inter-American Observatory in Chile. The last observations were completed shortly after Huchra’s death in October 2010.