Galaxy clusters are made up of hundreds to thousands of galaxies held together by gravity, yet the visible mass of these galaxies accounts for only a fraction of this attraction. The remainder is attributed to two sources: the intracluster medium (ICM), a superheated plasma detectable via X-ray emissions, and a hypothesized “dark matter” measureable only via its gravitational effects.
The researchers studied the ICM of galaxy cluster Abell 1689 using Suzaku, a powerful X-ray astronomical satellite developed in Japan, which they compared with observational data from the U.S. Sloan Digital Sky Survey (SDSS). /Suzaku/’s high sensitivity enabled them to probe well beyond the range of conventional detectors, to an area at the outskirts of the ICM with a plasma temperature of 23 million degrees, within which they discovered a high-temperature region reaching some 60 million degrees.
Extending outward from this high-temperature region, the researchers identified a large-scale filamentary structure of galaxies, and determined that it is a shock wave produced by the collision of cold gas from this filament with the galaxy cluster that heats the ICM. Combined with a gravitational lensing study using Japan's Subaru Telescope and the Hubble Space Telescope, the results provide a detailed picture, described in the April 9th issue of The Astrophysical Journal, of how cluster growth is affected by the large-scale structure of the surrounding universe.
For more information, please contact:
Dr. Madoka Kawaharada
Cosmic Radiation Laboratory
RIKEN Advanced Science Institute
(Currently belonging to ISAS/JAXA, ASTRO-H project team)
Tel: +81-(0)42-759-8510 / Fax: +81-(0)42-759-8546
Ms. Tomoko Ikawa (PI officer)
Global Relations Office
RIKEN
Tel: +81-(0)48-462-1225 / Fax: +81-(0)48-462-4715
Email: [email protected]
