What we can learn from galaxies far, far away
By:
Nassim Beiranvand
Graduate seminar
University of South Carolina
Fall 2015 ●Galaxy clusters are the largest objects in the universe held together by gravity.
●The study of clusters tells us about the way galaxies form and evolve.
2 George Ogden Abell (March 1, 1927 – October 7, 1983)
3 Abell catalogue
5 6 Classification:
Galaxy clusters are classified as rich or poor clusters depending on the number of galaxies they contain.
7 Rich clusters
-Contain hundreds to thousands of member galaxies.
-Are roughly spherical, with the largest galaxies near the center.
-Lots of hot gas and dust.
The Coma Cluster of Galaxies ( O. Lopez-Cruz (INAOEP), AURA, NOAO, NSF ) 8 Poor clusters
-Contain only tens of galaxies.
-Have a ragged, irregular Appearance.
-More spiral and irregular Galaxies.
The Fornax Irregular Cluster,form the Hubble Space Telescope.
9 ● Galaxy cluster are useful as the universe's most massive laboratories, And as laboratories, to describe galaxy clusters is to describe the experiments that you can do with them.
10 Big and massive
arges
Gioiello Cluster, picture from NASA’s Chandra X-ray Observatory
11 Gravitational lensing
This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MCS J0416.1–2403.
12 Hot gas
The El Gordo galaxy cluster is the largest, hottest, and most energetic cluster ever seen. picture from NASA’s Chandra X- ray Observatory 13 14 15 16 Pie chart showing the approximate ratios of dark matter and visible matter in the universe. By NASA. 17 N-body simulation
18 Why are clusters interesting?
● Largest, most massive systems in the universe.
● Probes of the history of structure and galaxy formation.
● Provide a history of nucleosynthesis in the universe.
● Fair samples of the universe- laboratory to measure dark matter.
● The gravitational potential is dominated by dark matter on all scales.
● Most of the baryons are in the hot gas (80%).
19 "If I had asked people what they wanted, they would have said faster horses."
Henry Ford
20 Reference
1.What we can learn from galaxies far, far away? Henry Lin,TED.com.
2.Galaxy Formation and Evolution, by Houjun Mo , Frank van den Bosch , Simon White, Cambridge, UK: Cambridge University Press, 2010.
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