Images
X-ray Images
Chandra Mission
X-ray Astronomy
Chandra People
Podcasts
Chandra in HD
Standard Definition
The Invisible Sky
Two Inch Universe
By Date/Category
Other Features
Animations & Video
Special Features
Audio
Resources
Q & A
Glossary
Acronym Guide
Further Reading
Desktop Images
iPhone Wallpapers
By Date/Category
Miscellaneous
Handouts
Image Handouts
Chandra Lithographs
Educational Activities
Printable Games
Chandra Fact Sheets
Presentations
Entire Collection
By Date
By Category
Presentations
Web Shortcuts
Chandra Blog
RSS Feed
Chandra Mobile
Chronicle
Email Newsletter
News & Noteworthy
Image Use Policy
Questions & Answers
Glossary of Terms
Download Guide
Get Adobe Reader
Image Use
Image Use Policy & Request Form
Guidelines for utilizing images, applets, movies, and animations featured in this Web Site.
Getting Hard Copies of Images
Ways to obtain photos, slides, etc of Chandra images.
Print Instructions
Downloading Tips
Dark Energy (Illustrations)

Method1
Method2
Method3
1. X-ray Distance Measurement Technique
This set of illustrations shows the technique used to make distance measurements to galaxy clusters. Chandra's observations are used to determine the ratio of the mass of the hot gas and the mass of the dark matter in different galaxy clusters. This "gas fraction" depends on the assumed distances to the clusters, which in turn depends on the amount of matter and dark energy in the Universe. Because galaxy clusters are extremely large, the gas fraction should be the same for every cluster, and so the distances to the clusters are adjusted to satisfy this requirement. Each of these 3 illustration shows Chandra in the top left, observing a galaxy cluster, shown in the top right (in red). The relative amounts of hot gas (in red) and dark matter (in blue) are shown at the bottom, with the green marker giving the expected, correct amount. The first illustration shows a gas fraction that is too small, implying that the distance to the cluster is too small, the second shows the correct gas fraction and distance, and the third illustration shows a gas fraction and distance that are too large. (Illustration: NASA/CXC/M.Weiss)

Related Photo Album

animation2
animation7
animation9
2. Animation Stills: Galaxy Cluster
These still images show a galaxy cluster, the largest gravitationally-bound objects in the Universe. Individual galaxies are shown in white and yellow, and the intergalactic gas is shown in red. Galaxy clusters contain as much mass as a million billion suns. The strong gravitational pull of this matter squeezes the gas and heats it to about 100 million degrees, making it only detectable in X-rays. Chandra found direct evidence for cosmic acceleration and dark energy, based on distance measurements to a sample of galaxy clusters. View Galaxy Cluster Animation
(Illustration: NASA/CXC/A.Hobart)

Related Photo Album