These images reveal the distribution of dark matter in the supercluster Abell 901/902, composed of hundreds of galaxies.
The image in the center shows the entire supercluster. Astronomers assembled this photo by combining a visible-light image of the supercluster taken with the MPG/ESO 2.2-meter telescope in La Silla, Chile, with a dark matter map derived from observations with NASA's Hubble Space Telescope.
The magenta-tinted clumps represent a map of the dark matter in the cluster. Dark matter is an invisible form of matter that accounts for most of the universe's mass. The image shows that the supercluster galaxies lie within the clumps of dark matter.
Hubble cannot see the dark matter directly. Astronomers inferred its location by analyzing the effect of so-called weak gravitational lensing, where light from more than 60,000 galaxies behind Abell 901/902 is distorted by intervening matter within the cluster. Researchers used the observed, subtle distortion of the galaxies' shapes to reconstruct the dark matter distribution in the supercluster. The image was assembled by combining a visible-light image of the supercluster with a map of the dark matter distribution.
The Hubble study pinpointed four main areas in the supercluster where dark matter has pooled into dense clumps. These areas match the location of hundreds of galaxies that have experienced a violent history in their passage from the outskirts of the supercluster into these dense regions. The four close-up images flanking the central photo are Hubble views of the four dense clumps of matter. To make this image, astronomers superimposed the dark matter map over a Hubble visible-light image of the supercluster galaxies.
The images are part of the Space Telescope Abell 901/902 Galaxy Evolution Survey (STAGES), which covers one of the largest patches of sky ever observed by the Hubble telescope. The area surveyed is so wide that it took 80 Hubble images to cover the entire field.
Hubble's Advanced Camera for Surveys made the observations in June and July 2005 and in January 2006.
Credits
Hubble Images: NASA, ESA, C. Heymans (University of British Columbia, Vancouver), M. Gray (University of Nottingham, U.K.), M. Barden (Innsbruck), and the STAGES collaboration;Ground-based Image: C. Wolf (Oxford University, U.K.), K. Meisenheimer (Max-Planck Institute for Astronomy, Heidelberg), and the COMBO-17 collaboration
| About The Object | |
|---|---|
| Object Name | Abell 901/902 (center), Abell 901a (top left), Abell 901b (top right), Abell 902 (bottom left), SW Group (bottom right) |
| Object Description | Space Telescope A901/902 Galaxy Evolution Survey (STAGES), Supercluster, Large Galaxy Cluster |
| R.A. Position | 10h |
| Dec. Position | -10 |
| Constellation | Leo |
| Distance | Redshift of z = 0.16 |
| Dimensions | The STAGES area covers 0.5x0.5 degrees which corresponds to an area of 5x5 Megaparsecs |
| About The Data | |
| Data Description | HST Proposal: M. Gray (University of Nottingham) The science team is being led by C. Heymans (University of British Columbia). The full list of team members is available at the STAGES team webpage. |
| Instrument | HST>ACS/WFC and MPG/ESO 2.2-meter telescope |
| Exposure Dates | June and July, 2005, Exposure Time: 1.6 days (HST data) |
| Filters | ACS/WFC: F606W (V) |
| About The Image | |
| Color Info | Visible: MPG/ESO Magenta (dark matter): F606W (V) |
| Compass Image |  |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
