Dark Flow

  • Released Wednesday, March 10, 2010
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Distant galaxy clusters mysteriously stream at a million miles per hour along a path roughly centered on the southern constellations Centaurus and Hydra. A new study led by Alexander Kashlinsky at NASA's Goddard Space Flight Center in Greenbelt, Md., tracks this collective motion — dubbed the "dark flow" — to twice the distance originally reported, out to more than 2.5 billion light-years.

The study used a new technique to determine the motion of X-ray-emitting galaxy clusters. The clusters appear to be moving along a line extending from our solar system toward Centaurus/Hydra, but the direction of this motion is less certain. Evidence indicates that the clusters are headed outward along this path, away from Earth, but the team cannot yet rule out the opposite flow.

The video shows the team's catalog of galaxy clusters separated into four "slices" representing different distance ranges. A colored ellipse shows the flow axis for the clusters within each slice. While the size and exact position of the ellipses vary, the overall trends show remarkable agreement. The video includes images of representative clusters in each distance slice.

The dark flow is controversial because the distribution of matter in the observed universe cannot account for it. Its existence suggests that some structure beyond the visible universe — outside our "horizon" — is pulling on matter in our vicinity.

Video showing direction of travel of galaxy clusters at four distances from Earth. The colored dots are clusters within one of four distance ranges, with redder colors indicating greater distance. Colored ellipses show the axis of bulk motion for clusters of the corresponding color. Images of representative galaxy clusters in each distance slice are also shown.

Credit: NASA/GSFC/A. Kashlinsky et al.

This all-sky view of the entire near-infrared sky reveals the distribution of galaxies beyond the Milky Way and has been desaturated to serve as the background for the dark flow plots. The image is derived from the 2MASS Extended Source Catalog, which contains more than 1.5 million galaxies, and the Point Source Catalog, which holds nearly 500 million stars within the Milky Way. The galaxies are color coded for distances obtained by various surveys. The nearest sources are blue (redshifts less than 0.01), moderately distant sources (redshifts between 0.01 and 0.04) are green, and red represents the farthest sources that 2MASS resolves (between redshifts of 0.04 and 0.1). For a labeled version that identifies specific features, please see http://spider.ipac.caltech.edu/staff/jarrett/papers/LSS/2MASS_LSS_chart-NEW.jpg. Credit: Courtesy of Dr. T.H. Jarrett (IPAC/Caltech)

This all-sky view of the entire near-infrared sky reveals the distribution of galaxies beyond the Milky Way and has been desaturated to serve as the background for the dark flow plots. The image is derived from the 2MASS Extended Source Catalog, which contains more than 1.5 million galaxies, and the Point Source Catalog, which holds nearly 500 million stars within the Milky Way. The galaxies are color coded for distances obtained by various surveys. The nearest sources are blue (redshifts less than 0.01), moderately distant sources (redshifts between 0.01 and 0.04) are green, and red represents the farthest sources that 2MASS resolves (between redshifts of 0.04 and 0.1). For a labeled version that identifies specific features, please see http://spider.ipac.caltech.edu/staff/jarrett/papers/LSS/2MASS_LSS_chart-NEW.jpg.

Credit: Courtesy of Dr. T.H. Jarrett (IPAC/Caltech)

"Dark flow" galaxy clusters and flow direction by distance.Credit: NASA/GSFC/A. Kashlinsky et al.

"Dark flow" galaxy clusters and flow direction by distance.

Credit: NASA/GSFC/A. Kashlinsky et al.

The colored dots are clusters within one of four distance ranges, with redder colors indicating greater distance. Colored ellipses show the axis of bulk motion for clusters of the corresponding color. Images of representative galaxy clusters in each distance slice are also shown. Credit: NASA/GSFC/A. Kashlinsky et al.

The colored dots are clusters within one of four distance ranges, with redder colors indicating greater distance. Colored ellipses show the axis of bulk motion for clusters of the corresponding color. Images of representative galaxy clusters in each distance slice are also shown.

Credit: NASA/GSFC/A. Kashlinsky et al.

The colored dots are clusters within one of four distance ranges, with redder colors indicating greater distance. Colored ellipses show the axis of bulk motion for clusters of the corresponding color. Images of representative galaxy clusters in each distance slice are also shown. Unlabeled.Credit: NASA/GSFC/A. Kashlinsky et al.

The colored dots are clusters within one of four distance ranges, with redder colors indicating greater distance. Colored ellipses show the axis of bulk motion for clusters of the corresponding color. Images of representative galaxy clusters in each distance slice are also shown. Unlabeled.

Credit: NASA/GSFC/A. Kashlinsky et al.

Coma Galaxy Cluster, redshift 0.023. The Coma Galaxy Cluster, also known as Abell 1656, is more than 300 million light-years away and is named for its parent constellation, Coma Berenices. It is one of the closest clusters participating in the dark flow. Credit: Jim Misti (Misti Mountain Observatory)

Coma Galaxy Cluster, redshift 0.023. The Coma Galaxy Cluster, also known as Abell 1656, is more than 300 million light-years away and is named for its parent constellation, Coma Berenices. It is one of the closest clusters participating in the dark flow.

Credit: Jim Misti (Misti Mountain Observatory)

Abell 667, redshift 0.145.Credit: Sloan Digital Sky Survey

Abell 667, redshift 0.145.

Credit: Sloan Digital Sky Survey

Abell 1689, redshift 0.181. Credit: NASA/ESA/L. Bradley (JHU) et al.

Abell 1689, redshift 0.181.

Credit: NASA/ESA/L. Bradley (JHU) et al.

Abell 520, redshift 0.203. Credit: CFHT/UVic./A.Mahdavi et al.

Abell 520, redshift 0.203.

Credit: CFHT/UVic./A.Mahdavi et al.

For More Information

See http://www.nasa.gov/centers/goddard/news/releases/2010/10-023.html

Credits

Please give credit for this page to NASA/Goddard Space Flight Center. However, each image should be credited as indicated above.

This page was originally published on Wednesday, March 10, 2010.
This page was last updated on Wednesday, May 3, 2023 at 1:54 PM EDT.

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Tapes

This visualization originally appeared on the following tapes:
  • Various Small Astrophysics projects (ID: 2010139)
    Friday, December 17, 2010 at 5:00AM
    Produced by - Robert Crippen (NASA)

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