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Lecture 20-21: The Formation of Structure---Galaxies, Clusters, Voids

Lecture 20-21: The Formation of Structure---Galaxies, Clusters, Voids. Astronomy 5: The Formation and Evolution of the Universe Sandra M. Faber Spring Quarter 2007 UC Santa Cruz. A major recent discovery: color bimodality. We are here. 1/4 of visible universe.

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Lecture 20-21: The Formation of Structure---Galaxies, Clusters, Voids

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  1. Lecture 20-21: The Formation of Structure---Galaxies, Clusters, Voids Astronomy 5: The Formation and Evolution of the Universe Sandra M. Faber Spring Quarter 2007 UC Santa Cruz

  2. A major recent discovery: color bimodality

  3. We are here 1/4 of visible universe A redshift survey: 220,000 galaxies Each small dot is a galaxy

  4. 4 billion light years

  5. 4 billion light years Milky Way galaxy Radius of cosmic horizon; 14 B lyr

  6. 4 billion light years Milky Way galaxy Radius of cosmic horizon; 14 B lyr

  7. We are here 1/4 of visible universe A redshift survey: 220,000 galaxies Each small dot is a galaxy

  8. Density along a line in the early Universe: Large cluster Small group Isolated galaxy Void The seeds of galaxy and structure formation are small density fluctuations that were created by inflation The highest peaks collapse first, making small proto-galaxies. Then lower peaks collapse to make galaxies, and finally clusters and superclusters.

  9. A chunk of the Universe first expanding and then collapsing. Dark matter only. Redshift, z Scale factor a = 1/(1+z). So Universe starts out 1/50th of present size.

  10. Now the viewpoint steps back as the Universe expands to show detail inside the cube. The expansion seems to disappear, but this is an effect of the presentation. Dark matter only.

  11. A thin slice through the cube. Still dark matter only. Simulation courtesy of Springel, White, and Hernquist

  12. Measles on the CMB map are the seeds of voids and superclusters. Ripples in the CMB intensity on the celestial sphere, as mapped with the WMAP satellite. The celestial sphere as portrayed from outside. The Milky Way is at the center of the sphere.

  13. Cosmic history in 4 easy steps Graphics from WMAP team

  14. The Hubble Ultradeep Field to scale

  15. Ultradeep field detail Near Near Far Far ???

  16. DEEP2 looks 2/3 of the way back to the Big Bang The DEEP2 Survey has gathered spectra of 50,000 galaxies using the DEIMOS spectrograph on the Keck 2 telescope. The typical galaxy is at z = 0.9 and is 100 times fainter than galaxies in low-redshift surveys like SDSS and 2dF.

  17. Lumps continually collide to make bigger lumps. Hierarchical clustering. Simulation courtesy of Springel, White, and Hernquist

  18. Our matter makes up only a tiny fraction of galactic mass. The remainder is in a halo of dark matter roughly 10 times as big and 10 times as massive.

  19. Visible galaxies embedded in the dark matter filaments

  20. Visible galaxies embedded in the dark matter filaments Formed stars

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