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Searching for modified growth patterns with tomographic surveys

Searching for modified growth patterns with tomographic surveys. Gong-Bo Zhao Simon Fraser University Aug 25,2008 COSMO08 With collaborators Levon Pogosian, Alessandra Silvestri, Joel Zylberberg. Outline. Introduction of modify GR - motivation

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Searching for modified growth patterns with tomographic surveys

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  1. Searching for modified growth patterns with tomographic surveys Gong-Bo Zhao Simon Fraser University Aug 25,2008 COSMO08 With collaborators Levon Pogosian, Alessandra Silvestri, Joel Zylberberg

  2. Outline • Introduction of modify GR - motivation • Non-GR implementation theoretically & numerically • Preliminary results of error forecast from future tomographic surveys – DES & LSST • Summary COSMO 08

  3. Universe is currently accelerating f(R), scalar-tensor … 4%Atoms 22% Dark Matter 74% Dark Energy COSMO 08

  4. Modified gravity At background level - degenerate with LCDM.At perturbation level - richer physics, such as scale-dependent growthNeed to study the cosmological structure formation to break the degeneracy See Fabian’s talk Cross- Correlations COSMO 08

  5. Newtonian Gauge GR: Comoving density perturbation 0 Non-GR: COSMO 08

  6. Synchronous Gauge Mapping CAMB implementation IC: GR value at z=30 COSMO 08

  7. Consistency check: Sub-horizon: Super-horizon: Consistency relation to obey causality in the infrared and the conservation of energy-momentum Bertschinger (2006) COSMO 08

  8. Non-GR parameterization Bertschinger & Zukin (2008) (BZ08) Other parameterizations (PPF, etc.), see Ignacy’s talk COSMO 08

  9. Powerful tool: Tomography Jain & Taylor (2003) Hu & Jain (2004) COSMO 08

  10. Observables for tomography We then calculate power spectra of TT, shear-shear, galaxy-galaxy, shear-CMB, galaxy-CMB and shear-galaxy by modifying CAMB code. No Limber Approximation used!! COSMO 08

  11. Surveys : SNAP, Planck, DES & LSST COSMO 08

  12. Surveys : DES & LSST COSMO 08

  13. CMB (3) Gal/Gal (55) CMB/Gal (10) CMB/WL (6) Gal/WL (60) WL/WL (21) For LSST, we have 155 Cls for each model!! COSMO 08

  14. 21 WL Cls 3 CMB Cls Cl Cutoff! 10 CMB/Gal Cls 55 Gal Cls 60 Gal/WL Cls 6 WL/CMB Cls COSMO 08

  15. Fisher Analysis For CMB, WL-WL, galaxy-galaxy: For CMB-WL, CMB-galaxy, WL-galaxy cross-correlations: Hu & Jain (2004) COSMO 08

  16. Noises COSMO 08

  17. Parameters: Preliminary results: Zhao, Pogosian, Silvestri & Zylberberg (2008), appear soon COSMO 08

  18. COSMO 08

  19. DES vs. LSST COSMO 08

  20. Reconstructing G_eff and gamma Fiducial model COSMO 08

  21. Summary • Tomographic surveys can provide powerful constraints on possible deviation from GR; • Results depends on the choice of fiducial model and parameterization; • Need to further study using non-parametric methods, such as principle component analysis (PCA) (in process). COSMO 08

  22. Appendix COSMO 08

  23. COSMO 08

  24. 3 vs. 4 COSMO 08

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