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Large-Scale Structure & Surveys
Max Tegmark, MITMax Tegmark, MIT
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
Onion
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Summary of last lecture
Fluctuation generator
Fluctuation amplifier
(Graphics from Gary Hinshaw/WMAP team)
Hot Dense SmoothCool Rarefied
Clumpy
Summary of last lecture
400
SN Ia+CMB+LSS constraintsYun Wang & MT 2004, PRL 92,
241302
Assumes k=0
Vanilla rules OK!
0th order: what we’ve learned about our expansion history
Summary of last lecture
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
Ly
LSS
Clusters
Lensing
Tegmark & Zaldarriaga, astro-ph/0207047 + updates
CMB
1st order: what we’ve learned about cosmic clustering
Summary of last lecture
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
1st order: what we’ve learned about cosmic clustering
Summary of last lecture
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
000619DO ANY OF THESE QUESTIONS CONFUSE YOU?
1. What is the Universe expanding into?
2. How can stuff be more than 14 billion light years away when the Universe is only 14 billion light years old?
3. Where in space did the Big Bang explosion happen?
4. Did the Big Bang happen at a single point?
5. How could a the Big Bang create an infinite space in a finite time?
6. How could space not be infinite?
7. If the Universe is only 10 billion years old, how can we see objects that are now 30 billion light years away?
8. Don’t galaxies receeding faster than c violate relativity theory?
9. Are galaxies really moving away from us, or is space just expanding?
10. Is the Milky Way expanding?
11. Do we have evidence for a Big Bang singularity?
12. What came before the Big Bang?
13. Should I feel insignificant?
QuickTime™ and a decompressor
are needed to see this picture.
The cosmic plan:• Survey of cosmology basics
• Measuring large-scale structure with galaxy surveys
• Measuring large-scale structure neutral hydrogen
L1:
L3:
L2:
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
Springel, Frenk & White 2006,
Nature, 440, 11
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
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
LSSde Lapparent, Geller & Huchra 1986
Cmbgg OmOl
LSS
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
Galaxy power spectrum measurements 1999(Based on compilation by Michael Vogeley)
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
PSCz 15000 gals:
(Data points uncorrelated)
(Hamilton, Tegmark & Padmanabhan 2000)
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
SDSS 2006:
2dFGRS 250000 gals
SDSS DR4 400000 gals, now ~106 gals
Cmbgg OmOl
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
(Table from Natalie Roe)
SOME SURVEYS TO LOOK FORWARD TO:
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
LAMOST: The Large Sky Area Multi-Object Fibre Spectroscopic Telescope
QuickTime™ and a decompressor
are needed to see this picture.
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
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
Why are LRGs so useful?
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
HistoryCMB
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6Our observable
universe
LSS
Our observable universe
LSS
Our observable universe
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
LSS
Common galaxies
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
LSS
Common gals: too dense
Quasars: too sparse
LRG’s: just right!
Why LRG’s are “Goldilocks galaxies”:60000 LRG’s have more statistical power than 2 million regular gals
• 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
Measuring large-scale structure with galaxy surveys:what are the challenges?
P ~ N-1/2(P+n-1)N ~ V k^3
So aim for as large V as possible with nP~1
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
Sky coverage of SDSS DR4 redshift survey
(Aitoff projection, equatorial coordinates)
(Dust map fromSchlegel, Finkbeiner & Davis)
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
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
MT, Hamilton, Strauss, Vogeley & Szalay 1998
SDSS
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
Sky coverage of SDSS DR4 redshift survey
(Aitoff projection, equatorial coordinates)
(Dust map fromSchlegel, Finkbeiner & Davis)
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
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
Virgo LCDM simulation
CMB
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
SDSS galaxies
CMB
Max TegmarkDept. of Physics, MIT
[email protected] en la Playa
January 11-15, 2010
LSS
Lum funcs & sel funcs by Michael Blanton (NYU)
LSS
Molly Swanson, MT, Mike Blanton, Idit Zehavi: arXiv:0702584
Molly Swanson, MT, Mike Blanton, Idit Zehavi: arXiv:0702584
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
