MACS J0025.4-1222
Encyclopedia
MACS J0025.4-1222 is a cluster created by the collision of two galaxy clusters. Like the earlier discovered Bullet Cluster
, this cluster shows a clear separation between the centroid of the intergalactic gas (of majority of the normal, or baryonic, mass), shown in pink and the mass centroids of the colliding clusters (blue). It provides independent, direct evidence for dark matter and supports the view that dark matter particles interact with each other only very weakly.
ACS and WFPC2 detectors and the Chandra
ACIS detector. The Hubble images were taken on November 5, 2006, and June 6, 2007. The visible light images from Hubble allowed astronomers to infer the distribution of total mass (both dark matter and normal matter). With gravitational lensing Hubble was then able to map the dark matter (colored in blue). The distribution of normal matter (pink) is mostly in the form of hot gas glowing brightly in X-rays. Its distribution was accurately mapped from Chandra data.
The two clusters that formed MACS J0025 are each almost a million billion times the mass of the Sun. They merged at speeds of millions of miles per hour, and as they did so the hot gas in each cluster collided with the hot gas in the other and slowed down. The dark matter (which interacts weakly) did not. The separation between the normal matter (pink) and dark matter (blue) therefore provides direct evidence for dark matter and supports the view that dark matter particles interact with each other almost entirely through gravity.
Bullet cluster
The Bullet cluster consists of two colliding clusters of galaxies. Studies of the Bullet cluster, announced in August 2006, provide the best evidence to date for the existence of dark matter...
, this cluster shows a clear separation between the centroid of the intergalactic gas (of majority of the normal, or baryonic, mass), shown in pink and the mass centroids of the colliding clusters (blue). It provides independent, direct evidence for dark matter and supports the view that dark matter particles interact with each other only very weakly.
Details
The shown image is a composite of separate exposures made by Hubble Space TelescopeHubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
ACS and WFPC2 detectors and the Chandra
Chandra X-ray Observatory
The Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999. It was named in honor of Indian-American physicist Subrahmanyan Chandrasekhar who is known for determining the maximum mass for white dwarfs. "Chandra" also means "moon" or "luminous" in Sanskrit.Chandra...
ACIS detector. The Hubble images were taken on November 5, 2006, and June 6, 2007. The visible light images from Hubble allowed astronomers to infer the distribution of total mass (both dark matter and normal matter). With gravitational lensing Hubble was then able to map the dark matter (colored in blue). The distribution of normal matter (pink) is mostly in the form of hot gas glowing brightly in X-rays. Its distribution was accurately mapped from Chandra data.
The two clusters that formed MACS J0025 are each almost a million billion times the mass of the Sun. They merged at speeds of millions of miles per hour, and as they did so the hot gas in each cluster collided with the hot gas in the other and slowed down. The dark matter (which interacts weakly) did not. The separation between the normal matter (pink) and dark matter (blue) therefore provides direct evidence for dark matter and supports the view that dark matter particles interact with each other almost entirely through gravity.