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Searching for modified growth patterns with tomographic surveys

Delve into the study of cosmological structure formation to uncover deviations from General Relativity using tomographic surveys and powerful constraints. Analyze preliminary results, parameterizations, and observables impacting growth patterns.

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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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