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Large-Scale Structure & Surveys

Large-Scale Structure & Surveys. Max Tegmark, MIT. Summary of last lecture. Onion. Tegmark 2002, Science, 296, 1427-33. Summary of last lecture. Fluctuation generator. Fluctuation amplifier. Hot Dense Smooth. 400. Cool Rarefied Clumpy. (Graphics from Gary Hinshaw/WMAP team).

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Large-Scale Structure & Surveys

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  1. Large-Scale Structure & Surveys Max Tegmark, MIT

  2. Summary of last lecture Onion Tegmark 2002, Science, 296, 1427-33

  3. Summary of last lecture Fluctuation generator Fluctuation amplifier Hot Dense Smooth 400 Cool Rarefied Clumpy (Graphics from Gary Hinshaw/WMAP team)

  4. 0th order: what we’ve learned about our expansion history Summary of last lecture Assumes k=0 SN Ia+CMB+LSS constraints Yun Wang & MT 2004, PRL 92, 241302 Vanilla rules OK!

  5. 1st order: what we’ve learned about cosmic clustering Summary of last lecture CMB Clusters LSS Lensing Lya Tegmark & Zaldarriaga, astro-ph/0207047 + updates

  6. 1st order: what we’ve learned about cosmic clustering Summary of last lecture

  7. DO ANY OF THESE QUESTIONS CONFUSE YOU? What is the Universe expanding into? How can stuff be more than 14 billion light years away when the Universe is only 14 billion light years old? Where in space did the Big Bang explosion happen? Did the Big Bang happen at a single point? How could a the Big Bang create an infinite space in a finite time? How could space not be infinite? If the Universe is only 10 billion years old, how can we see objects that are now 30 billion light years away? Don’t galaxies receeding faster than c violate relativity theory? Are galaxies really moving away from us, or is space just expanding? Is the Milky Way expanding? Do we have evidence for a Big Bang singularity? What came before the Big Bang? Should I feel insignificant? 000619

  8. The cosmic plan: • Survey of cosmology basics • Measuring large-scale structure with galaxy surveys • Measuring large-scale structure neutral hydrogen L1: L2: L3:

  9. Springel, Frenk & White 2006, Nature, 440, 11

  10. Measuring large-scale structure with galaxy surveys: what are the challenges? • Statistical errors • - Sample variance: want big V • - Shot noise: want large n • Systematic errors • - Dust extinction (angular selection function) • - Radial selection function errors • Data analysis • - Survey geometry (window functions) • - Numerical challenges • Linking light to mass: • - bias • - redshift distortions • - nonlinearities P ~ N-1/2(P+n-1) N ~ V k^3 So aim for as large V as possible with nP~1

  11. de Lapparent, Geller & Huchra 1986 LSS

  12. LSS

  13. LSS

  14. Cmbgg OmOl LSS

  15. Galaxy power spectrum measurements 1999 (Based on compilation by Michael Vogeley)

  16. PSCz 15000 gals: (Data points uncorrelated) (Hamilton, Tegmark & Padmanabhan 2000)

  17. 2dFGRS 250000 gals SDSS DR4 400000 gals, now ~106 gals SDSS 2006:

  18. APO SDSS

  19. SDSS Zoom SDSS

  20. Cmbgg OmOl

  21. SOME SURVEYS TO LOOK FORWARD TO: (Table from Natalie Roe)

  22. LAMOST: The Large Sky Area Multi-Object Fibre Spectroscopic Telescope

  23. Measuring large-scale structure with galaxy surveys: what are the challenges? • Statistical errors • - Sample variance: want big V • - Shot noise: want large n • Systematic errors • - Dust extinction (angular selection function) • - Radial selection function errors • Data analysis • - Survey geometry (window functions) • - Numerical challenges • Linking light to mass: • - bias • - redshift distortions • - nonlinearities P ~ N-1/2(P+n-1) N ~ V k^3 So aim for as large V as possible with nP~1

  24. Why are LRGs so useful?

  25. Our observable universe History CMB Foreground-cleaned WMAP map from Tegmark, de Oliveira-Costa & Hamilton, astro-ph/0302496 Last scattering surface

  26. Our observable universe LSS Last scattering surface 21cm tomography

  27. Our observable universe LSS Last scattering surface

  28. LSS Quasars

  29. LSS LRG’s

  30. LSS Common galaxies

  31. Why LRG’s are “Goldilocks galaxies”: 60000 LRG’s have more statistical power than 2 million regular gals LSS LRG’s: just right! Common gals: too dense Quasars: too sparse

  32. Measuring large-scale structure with galaxy surveys: what are the challenges? • Statistical errors • - Sample variance: want big V • - Shot noise: want large n • Systematic errors • - Dust extinction (angular selection function) • - Radial selection function errors • Data analysis • - Survey geometry (window functions) • - Numerical challenges • Linking light to mass: • - bias • - redshift distortions • - nonlinearities P ~ N-1/2(P+n-1) N ~ V k^3 So aim for as large V as possible with nP~1

  33. Sky coverage of SDSS DR4 redshift survey (Aitoff projection, equatorial coordinates) (Dust map fromSchlegel, Finkbeiner & Davis)

  34. Cmbgg OmOl

  35. Measuring large-scale structure with galaxy surveys: what are the challenges? • Statistical errors • - Sample variance: want big V • - Shot noise: want large n • Systematic errors • - Dust extinction (angular selection function) • - Radial selection function errors • Data analysis • - Survey geometry (window functions) • - Numerical challenges • Linking light to mass: • - bias • - redshift distortions • - nonlinearities P ~ N-1/2(P+n-1) N ~ V k^3 So aim for as large V as possible with nP~1

  36. MT, Hamilton, Strauss, Vogeley & Szalay 1998 SDSS

  37. LSS

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