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Dark Matter
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1.I. Nicolson, Dark Side of the Universe (Johns Hopkins University Press, Baltimore, 2007), Chap. 3.
2.D. Lincoln, Understanding the Universe: From Quarks to the Cosmos (Revised) (World Scientific Press, Singapore, 2012).
3.Ref. 1, pp. 7679.
4.Ref. 1, Chap. 4.
5.Ref. 1, pp. 4546.
6.Ref. 2, pp. 335340.
7.Ref. 1, pp. 6067.
8.Ref. 1, pp. 6872.
9.Ref. 1, p. 75.
10.Ref. 1, pp. 8788.
11.Dan Hooper, “TASI Lectures on Dark Matter,” arXiv:0901.4090vl [hep-ph].
12.Ref. 2, pp. 393409.
13.D. Lincoln, The Quantum Frontier: The Large Hadron Collider (Johns Hopkins University Press, Baltimore, 2009), pp. 3543.
View: Figures


Image of Fig. 1.

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Fig. 1.

Rotation curves of thousands of galaxies tell the same tale. Inside the galaxy, data and theory are in agreement. However, in the outskirts of the galaxy, stars are observed to orbit with nearly constant velocity. This is in striking contrast with predictions. (Figure adapted from Ref. 2 .)

Image of Fig. 2.

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Fig. 2.

When a massive body passes between a distant star and your eye (top), it will gravitationally lens the light from the star so that more light hits your instrument (middle). A representative brightening curve is shown in the bottom figure. The vertical axis is relative brightness, with the light output before the microlensing event normalized to unity. In order to guard against stars with naturally varying light output, several different colors are sampled to ensure that all colors brighten equally. If they do, this is a candidate microlensing event. (Figure adapted from Ref. 2 .)

Image of Fig. 3.

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Fig. 3.

Motion of the Earth through the WIMPs passing through the solar system results in a varying velocity between the WIMPs and the detectors. This variation could lead to an annual modulation in the experiment's observation rate of WIMP candidates.

Image of Fig. 4.

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Fig. 4.

This NASA image shows the collision of two clusters of galaxies. The red regions are hot hydrogen gas left between the two clusters as a consequence of the collision. The blue regions show where the bulk of the mass is to be found. This mass is colocated with the visible galaxies and is far larger than contained in the galaxies themselves. This observation is considered to be strong evidence that the cold dark matter hypothesis is correct. (Figure courtesy NASA.)


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It's a dark, dark universe out there, and I don't mean because the night sky is black. After all, once you leave the shadow of the Earth and get out into space, you're surrounded by countless lights glittering everywhere you look. But for all of Sagan's billions and billions of stars and galaxies, it's a jaw-dropping fact that the ordinary kind of matter like that which makes up you and me is but 5% of the energy budget of the universe. The glittering spectacle of the heavens is a rather thin icing on a very large and dark cake.


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Scitation: Dark Matter