What we can learn from galaxies
far, far away?
By:
Nassim Beiranvand
Graduate seminar
University of South Carolina
Fall 2015
Abell 2744 galaxy cluster
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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.
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Galaxy clusters are classified as
rich or poor clusters depending on
the number of galaxies they contain.
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Regular Clusters
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Irregular clusters
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Regular Clusters
Regular clusters are giant
systems. Most of the
galaxies in these clusters
are elliptical. They can
frequently contain 1000's of
galaxy members. These
clusters tend to form roughly
spherical clouds. They also
usually have very large
galaxies in the center and
spiral galaxies only on their
edges, if they have them at
all. Regular clusters often
contain a lot of hot gas. An
example of a regular cluster
is the Coma cluster.
The Coma Cluster of Galaxies ( O. Lopez-Cruz (INAOEP),
AURA, NOAO, NSF )
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Irregular Clusters
Irregular galaxy clusters can be
many different shapes and
densities. They can be small
groups, a loose collection with
many centers, or large and
spread out. They typically do not
contain as many galaxies as the
regular type. Our galaxy is a
member of an irregular cluster,
known as the Local Group. This
group contains approximately 30
members, including our Milky
Way, Andromeda, the Large
Magellanic Cloud, the Small
Magellanic Cloud, and many
other dwarf galaxies.
The Fornax Irregular Cluster,form the Hubble Space
Telescope.
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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.
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Big and Massive
Gioiello Cluster, picture from NASA’s Chandra X-ray
Observatory
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Gravitational lensing
This image from the NASA/ESA Hubble Space Telescope shows the galaxy
cluster MCS J0416.1–2403.
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Very Hot
The El Gordo galaxy cluster is the largest, hottest, and most
energetic cluster ever seen. picture from NASA’s Chandra Xray Observatory
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Very Small
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Dark Matter
Pie chart showing the approximate ratios of dark matter and
visible matter in the universe. By NASA.
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Large scale structure of the universe
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"If I had asked people what they
wanted, they would have said faster
horses."
Henry Ford
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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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