This is where you can learn about the first galaxies in the universe, how we can use supercomputers to study them, and what this site enables you to do.
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Learn about the first galaxies in the universe
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Learn about how we use supercomputers to study them
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Learn about the Renaissance Simulations Laboratory
The Universe at t=13,800,000,000 yr (credit) (learn more)
The universe is filled with countless galaxies today. But there was a time not long after the big bang when there were no galaxies at all—just tiny fluctuations in the density of matter. How does a featureless universe “grow galaxies”? And how do they differ from modern galaxies like the Milky Way?
The Universe at t=380,000,000 yr (credit) (learn more)
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Gravity collects regions of slight overdensity in the early universe into dense clumps of gas and dark matter cosmologists call halos. These halos merge and coalesce to form the first galaxies (protogalaxies). As time goes on, protogalaxies merge and coalesce into larger galaxies, and so on, until today we have a variety of galaxy types and sizes. These include large spiral galaxies like the Milky Way, and large elliptical galaxies, like M87. Thus, galaxies are said to grow hierarchically, with large modern galaxies representing the assembly of thousands of protogalaxies which are much smaller.
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Can we observe the first galaxies directly? No. They are too small and too faint for the Hubble Space Telescope (HST) to detect them. However the HST can detect very faint, distant galaxies which are likely second and third generation galaxies. The graphic at right shows how deep the HST has been able to probe. The Hubble Ultra Deep Field has detected galaxies when the universe was only 400-700 million years old, which is only a few percent of its present age.
The James Webb Space Telescope, to be launched by NASA in 2018, should be able to observe even younger galaxies, pushing into the realm of truly first galaxies.
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While not strictly the first galaxies in the universe, the most distant galaxies detected by the HST are worthy of study. They appear as faint red blobs in the Hubble Ultra Deep Field. They are red because the expansion of the universe has redshifted their starlight into the red part of the visible spectrum. They are faint because they are distant. And they are very small compared to the Milky Way galaxy. A typical size is about 500 parsec, which is 1/50 the size of the Milky Way galaxy.
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