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Modified Gravity at Dome APowerPoint Presentation

Modified Gravity at Dome A

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Modified Gravity at Dome A

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- Acceleration of Universe
- Background level
- Evolution of expansion: H(a), w(a)
- degeneracy: DE & MG

- Perturbation level
- Evolution of inhomogeneity: G(a), G(a, k), Phi, Psi…

- Background level
- Smoothing energy component or modified gravity?
- Scalar field
- F(R), DGP, TeVeS,

- Growth of LSS
- Expansion: H(a)
- consistency relation: H_growth vs. H_expansion

- Metric perturbation:

- Expansion: H(a)

- Modified Gravity
- H(a)
- Modified Poisson equation.
- G_eff

- Parametrization
- Growth index (scale-independent)

- convergence power (cross) spectrum

- rich information (power spectrum, cross-spectrum)

- photo-z error

standard ruler

- Spectroscopic survey
- δ field
- Growth factor G(z)

- v field
- (redshift distortion)
- β~ dlnG/dlna

- δ field

- Spectroscopic redshift surveys
- Measure beta from the anisotropy
- Measure galaxy bias
- Obtain f

Current measurements

Guzzo et al. 2008

Acquaviva et al. 2008

2009 XuGuangqi-Galieo conference

- Standard Candle

- variation of SN peak L (after the standardization)

- photo-z error (without spectrum)

- z-dependent peak L (e.g. SN evolution, extinction)

- mass of clusters are not measured directly (except for WL)

- SZ flux decrement, X-ray temperature, gas mass

- mass selection function

- complex baryon physics (hydrodynamics, galaxies formation)

- number distribution

- angular density

- BAO

- Spectroscopic survey

- Photometric survey

Supernovae

- 200 SNIa/year/deg^2 available for z<1.2 (limit for ground experiment)

- SN1: 50 /y/deg^2

- SN2: 100 /y/deg^2

- Systematics (Nuisance parameters):

- photo-z error

- N_c: # of spectra for calibration

- absolute magnitude

- quadratic offset

- Weak Lensing (same as Sun lei & Zhao Gongbo)

- Clusters Count

- Genus
- Gaussian fluctuation:
- 3D (δ)
- 2D (weak lensing, κ)

- Gaussian fluctuation:

- Resistant against:
- Bias, redshift distortion, weak nonliearity.

- In GR
- Invariant amplitude.
- Standard ruler

- In MG
- Introduce new scale-dependence
- time-varying
- Complementaryto growth rate of matter fluctuation.
- Sensitive to scale-dependent modification at sub-horizon scale.

Fisher calculation:

?

=

from peculiar velocity

Gravitational

lensing

Galaxy redshifts to recover redshift information

(2D ->3D)

2009 XuGuangqi-Galieo conference

- EG will be measured to 1% level accuracy within two decades
- Promising to detect one percent level deviation from general relativity+canonical dark energy model (if systematics can be controlled)!

LCDM

f(R)

DGP

MOND/TeVeS

ZPJ et al. 2007

2009 XuGuangqi-Galieo conference

One can further construct an estimator ofLensing: Φ-Ψ; Peculiar velocity: Ψ

DGP

dark energy with anisotropic stress

- eta can be measured to 10% accuracy.
- Errors in eta is larger than errors in E_G
- Even so, eta can have stronger discriminating power, in some cases.
- η of DGP differs significantly from that of LCDM. (EG of DGP is very close to that of LCDM.)

- eta and E_G are complementary
- DGP with high Omega_m

MOND

TeVeS

ZPJ et al. 2008

SKA forecast

2009 XuGuangqi-Galieo conference

Thanks