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LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

Baryon Acoustic Oscillations from Billions of Galaxies Hu Zhan 1 and Andrew Hamilton 2 1 UC Davis, 2 JILA, U. Colorado. LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006. Outline. Baryon acoustic oscillations as a standard ruler for cosmology

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LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

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  1. Baryon Acoustic Oscillations from Billions of Galaxies Hu Zhan1 and Andrew Hamilton21UC Davis, 2JILA, U. Colorado LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  2. Outline • Baryon acoustic oscillations as a standard ruler for cosmology • Measuring BAOs/galaxy angular correlations from billions of galaxies with photometric redshifts • Synergy with weak lensing: galaxy-shear correlation, galaxy bias, and photo-z error distribution • Summary LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  3. From Daniel Eisenstein Baryon Acoustic Oscillations: Photon-Pressure Supported Waves Curvature perturbation  pressure imbalance  sound waves (cs ~ c /√3) Wave stalls at recombination Sound horizon RS~150Mpc Galaxies form in overdense regions excess correlation at ~150Mpc oscillations in power spectrum LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  4. CMB temp. fluctuations (WMAP) Angular diameter distance & Hubble parameter RS = cDz/H = DqDA RS~150 Mpc BAOs in multipole space (Sound horizon at recombination) LSST galaxy angular PS Deep Lens Survey, Tyson & Wittman Baryon Acoustic Oscillations from Billions of Galaxies Imprints on the matter power spectrum (White 2005) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  5. Rs = cDz/H RS DA With spectroscopy Dq Photo-z BAO Cosmology with Rulers WDE w0 wa … LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  6. Baryon Acoustic Oscillations dg(x+Dx) Dx x(r) dg(x) SDSS LRGs Eisenstein et al (2005) Comoving separation (h-1 Mpc) BAOs in multipole space Deep Lens Survey, Tyson & Wittman Angular PS Zhan (2006) Correlation Function Power Spectrum Galaxy 2-Point Correlation Function LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  7. Galaxy Power Spectrum Photometric redshift bins Auto Power Spectrum Kernel∝galaxy distribution in true-redshift space LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  8. Galaxy Power Spectrum Photometric redshift bins Cross Power Spectrum Kernel∝galaxy distribution in true-redshift space Overlap of galaxy distributions  Cross power spectrum (Limber approx) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  9. Galaxy Power Spectrum Photometric redshift bins Cross Power Spectrum Kernel∝galaxy distribution in true-redshift space Overlap of galaxy distributions  Cross power spectrum (Limber approx) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  10. Galaxy Power Spectrum Photometric redshift bins Cross Power Spectrum Kernel∝galaxy distribution in true-redshift space Overlap of galaxy distributions  Cross power spectrum (Limber approx) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  11. Galaxy Power Spectrum Photometric redshift bins Cross Power Spectrum Kernel∝galaxy distribution in true-redshift space Overlap of galaxy distributions  Cross power spectrum (Limber approx) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  12. Galaxy Power Spectrum Photometric redshift bins Kernel∝galaxy distribution in true-redshift space Zhan (2006) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  13. Prospects • Error depends on binning. • Error scales ~√sz. • No gain from sub-sampling (for better photo-zs) at z > 1.5. • Lower k-cut at lower z to reduce the effect of nonlinearity. • Spectra shifted vertically for clarity. LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  14. Forecasts LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  15. International photo-z calibration campaign Impact of Systematics LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  16. Impact of Systematics Ma, Hu, & Huterer (2006); Huterer et al (2006); Zhan (2006) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  17. Response to Photo-z Bias LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  18. Response to Photo-z Bias LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  19. Response to Photo-z rms LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  20. Response to Photo-z rms Galaxy power spectra are more sensitive to photo-z errors than shear power spectra and, hence, can be used to self-calibrate the photo-z error distribution. Zhan & Knox (2006); Zhan (2006); Schneider et al. (2006); Newman (in prep) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  21. LSST BAO & WL The LSST constraint on curvature is 10 times better than that obtained by WMAP 3yr + SNLS [s(WK) ∼ 0.02] or that achievable by Planck. LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  22. LSST BAO “+” WL BAO “+” WL: simple combination without sharing photo-z parameters and no galaxy-shear correlation, same as in DETF. LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  23. LSST BAO + WL BAO + WL: a joint analysis benefits from the extra information in the galaxy-shear correlation, determination of the galaxy (linear) bias, and BAO calibration of photo-z parameters. LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  24. LSST BAO + WL + SNe SN results are sensitive to the prior on SN evolution, SN photo-zs, and redshift range of sample. SNe + Planck constrain WK to 10-2. SNe and WL do not improve wm appreciably over Planck. LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  25. Complementarity between WL and BAO Galaxy clustering bias Photo-z bias Photo-z rms Spectroscopic calibrations must be carried out to parametrize the photo-z error distribution! LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  26. Curvature? Knox, Song, & Zhan (2006) BAO and WL can constrain WK to 10-3, and hence their constraints on the dark energy equation-of-state parameters are much less sensitive to the flatness assumption than SNe+CMB. LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  27. Challenges • Nonlinear evolution • Scale-dependent galaxy bias on small scales • Sample selection • Photo-z error distribution • Photometry precision • Extinction … LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  28. Nonlinearity • The BAO scale does not shift in the matter PS (but may shift in the halo PS, Eisenstein, Seo, & White 2006). • Nonlinear evolution causes a Gaussian suppression to the BAOs. • NE increases the cosmic variance and leads to mode coupling (more pronounced on smaller scales). • Simulations are crucial for precise calibration. Rimes & Hamilton 2006, in prep LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  29. Simulations Spingel et al. (2005) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  30. Nonlinearity Spingel et al. (2005) LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

  31. Summary • LSST will detect BAOs with high confidence. • Galaxy power spectra are helpful for calibrating the photo-z error distribution, which is important for WL surveys. • A joint analysis of BAO and WL will lead to powerful and robust constraints on cosmological parameters. • We must fully investigate theoretical uncertainties and systematics through end-to-end simulations (N-body, hydro, star/galaxy formation, photo-z algorithm, weather, photometry, operation, …). LSST All-Hands Meeting Stanford Linear Accelerator Center (SLAC) December 4 – 8, 2006

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