EMSS 1358+6245:
Chandra Probes Nature of Dark Matter

The cluster of galaxies EMSS 1358+6245 about 4 billion light year away in the constellation Draco is shown in this Chandra image. When combined with Chandra's X-ray spectrum, this image allowed scientists to determine that the mass of dark matter in the cluster is about 4 times that of normal matter.

The relative percentage of dark matter increases toward the center of the cluster. Measuring the exact amount of the increase enabled astronomers to set limits on the rate at which the dark matter particles collide with each other in the cluster. This information is extremely important to scientists in their quest to understand the nature of dark matter, which is thought to be the most common form of matter in the universe.

Fast Facts for EMSS 1358+6245: Credit  NASA/MIT/J.Arabadjis et al. Scale  Image is 3.8 arcmin across. Category  Groups & Clusters of Galaxies Coordinates (J2000)  RA 13h 59m 50.60s | Dec +62° 31' 04" Constellation  Draco Observation Dates  Sept 3-4, 2000 Observation Time  15 hours Color Code  Intensity Instrument  ACIS Distance Estimate  4 billion light years Release Date  September 06, 2001