Astronomy Chapter 16
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- Galaxies are distributed
- as if they are confined to the surface of giant bubbles
- Where are the largest voids?
- In the centers of these bubbles
- The highest concentrations of galaxies occur
- along filaments at the intersections of different bubbles.
- The mass of the Milky way is determined by...
- rotational curves
- yet the mass of other galaxies are determined in clusters by...
- When the cluster is gravitationally bound the binding energy needed to hold the cluster together is determined and then the mass can be obtained.
- What is the problem with this method?
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Masses we get are way bigger than in reality BECAUSE of dark matter.
IN FACT in binary systems dark matter may account for up to 90-99% of the mass. - How do galaxies form?
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Galaxies form as small fragments (larger than globular clusters) that merge together.
Smaller galaxies get assimilated into larger ones. - when we look into the past (very far away) what do we see?
- blue galaxies the building blocks of modern day galaxies.
- Where do galaxies with supermassive black holes in their centers fit into the evolution of galaxies?
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it is believed that those with black holes in their centers were very distant quasars.
So it is believed that quasars are in a stage of early galaxy development. - Recent measurements have found a relationship between the mass of the central black hole and the size of the galactic bulge. What is the pattern?
- The larger the black hole the larger the bulge.
- Overall galaxy evolution
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As small galaxies clump together to form larger ones= a black hole forms in the middle.
With plenty of fuel at the beginning burning is bright= quasar
additional mergers and depletion of fuels results in radio and seyfert galaxies (active galaxies).
Upon futher depletion of fuels NORMAL GALAXIES with a dormant black hole are formed.