Modified gravity at dome a
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Modified Gravity at Dome A. Dark Energy & Modified Gravity. 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… Smoothing energy component or modified gravity?

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Modified Gravity at Dome A

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Modified gravity at dome a

Modified Gravity at Dome A


Dark energy modified gravity

Dark Energy & Modified Gravity

  • 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…

  • Smoothing energy component or modified gravity?

    • Scalar field

    • F(R), DGP, TeVeS,


Growth of lss

Growth of LSS

  • Growth of LSS

    • Expansion: H(a)

      • consistency relation: H_growth vs. H_expansion

    • Metric perturbation:


Growth of lss1

Growth of LSS

  • Modified Gravity

    • H(a)

    • Modified Poisson equation.

      • G_eff

  • Parametrization

    • Growth index (scale-independent)


Weak lensing

Weak Lensing

  • convergence power (cross) spectrum

  • rich information (power spectrum, cross-spectrum)‏

  • photo-z error


Galaxy survey

standard ruler

Galaxy Survey

  • Spectroscopic survey

    • δ field

      • Growth factor G(z)

    • v field

      • (redshift distortion)

      • β~ dlnG/dlna


A sensitive measure of gravity

A sensitive measure of gravity

  • 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


Type ia supernovaes

Type IaSupernovaes

  • Standard Candle

  • variation of SN peak L (after the standardization)‏

  • photo-z error (without spectrum)‏

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


Clusters number count

Clusters Number Count

  • 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)‏


Preliminary plan

Preliminary plan

  • number distribution

  • angular density


Preliminary plan1

Preliminary plan

  • BAO

  • Spectroscopic survey

  • Photometric survey


Preliminary plan2

Supernovae

Preliminary plan

  • 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


Preliminary plan3

Preliminary plan

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


Preliminary plan4

Preliminary plan

  • Clusters Count


Mg at dome a

MG at Dome A


Genus of lss

Genus of LSS

  • Genus

    • Gaussian fluctuation:

      • 3D (δ)

      • 2D (weak lensing, κ)


Genus amplitude standard ruler

Genus Amplitude —— Standard Ruler

  • 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.


Genus of mg

Genus of MG

Fisher calculation:


Testing the generalized poisson equation

Testing the (generalized) Poisson Equation

?

=

from peculiar velocity

Gravitational

lensing

Galaxy redshifts to recover redshift information

(2D ->3D)

2009 XuGuangqi-Galieo conference


Modified gravity at dome a

  • 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


Modified gravity at dome a

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


Modified gravity at dome a

Thanks


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