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
08/025/08
COSMO 08

3. Universe is currently accelerating
74%
Dark Energy
22% Dark
Matter
4%Atoms
f(R), scalar-tensor …
08/025/08
COSMO 08

4. Modified gravity
At background level - degenerate with LCDM. At perturbation level - richer physics, such as scale-dependent growth Need to study the cosmological structure formation to break the degeneracy
See Fabian’s talk
Cross-
Correlations
08/025/08
COSMO 08

5. Newtonian Gauge GR: Non-GR: Comoving density perturbation 08/025/08
Non-GR:
08/025/08
COSMO 08

6. IC: GR value at z=30 Synchronous Gauge Mapping CAMB implementation
08/025/08
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)
08/025/08
COSMO 08

8. Non-GR parameterization
Bertschinger & Zukin (2008) (BZ08)
Other parameterizations (PPF, etc.), see Ignacy’s talk
08/025/08
COSMO 08

9. Powerful tool: Tomography
Jain & Taylor (2003)
Hu & Jain (2004)
08/025/08
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!!
08/025/08
COSMO 08

11. Surveys : SNAP, Planck, DES & LSST
08/025/08
COSMO 08

12. Surveys : DES & LSST
08/025/08
COSMO 08

13. Gal/Gal (55) Gal/WL (60) WL/WL (21)E T
G1 … … G10
WL1… … WL6 G1 .
G10
WL1
WL6
CMB
(3)
CMB/WL (6)
CMB/Gal (10)
Gal/Gal
(55)
Gal/WL
(60)
WL/WL
(21)
For LSST, we have 155 Cls for each model!!
COSMO 08
08/025/08

14. Cutoff! Cl 21 WL Cls 3 CMB Cls 10 CMB/Gal Cls 55 Gal Cls 60 Gal/WL Cls
6 WL/CMB Cls
08/025/08
COSMO 08

15. Fisher Analysis Hu & Jain (2004) For CMB, WL-WL, galaxy-galaxy:
For CMB-WL, CMB-galaxy, WL-galaxy cross-correlations:
Hu & Jain (2004)
08/025/08
COSMO 08

16. Noises
08/025/08
COSMO 08

17. Parameters: Preliminary results:
Zhao, Pogosian, Silvestri & Zylberberg (2008), appear soon
08/025/08
COSMO 08

18. 08/025/08
COSMO 08

19. DES vs. LSST
08/025/08
COSMO 08

20. Reconstructing G_eff and gamma
Fiducial model
08/025/08
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).
08/025/08
COSMO 08

22. Appendix
08/025/08
COSMO 08

23. 08/025/08
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24. 3 vs. 4
08/025/08
COSMO 08