David F. Mota

Institute of Theoretical Astrophysics University of Oslo

Nonlinear Cosmological Probes of Screening Mechanisms in Modified Gravity

Scalar-Tensor Theories with Chameleon or Symmetron screening mechanisms

10-3cm 1AU 1kpc 1Mpc 1000Mpcextra dimensions? GR Modified Gravity?

Extremely tight constraints on Modified Gravity from experiments at small scales!

Cassini ProbeLunar Laser Range

SupernovaeSupernovae + Large Scale StructuresSupernovae + Large Scale Structures + CMBRSupernovae + Large Scale Structures + CMBR + Baryon Oscillations

Decelerated Expansion

Accelerated Expansion

PLANCK

SDSS

High-Z Supernovae Search Team

GR

Large Scale Structure Formation: deviations from GR must be small

Amargui,Elgaroy, DFM, A&A

GRf(R)

Structure formation probes deviations from GR

Llinares, DFM & Winther, ApJ

rStronger coupling -> bigger deviations from LCDM Larger range -> large scale deviations from LCDM

Short range Long range

Structure formation dependence on coupling and range

r

Llinares, DFM & Winther, ApJ

screening at high densities

Structure formation dependence on the screening scale

Chameleon screening

critical scale

screening at high densities

screening at low densitiesscreening at low densities

Symmetron screening

Gronke, Llinares, DFM, A&A

Very difficult to differentiate between Chameleon and Symmetron

f

VeffHfL

f

VeffHfL

ScreenedUnscreened!

Symmetron Unique Feature

Symmetron Domain Wallsf

VeffHfL

f

VeffHfL

Llinares & DFM, PRL

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

0.1 1 10

(Pfu

ll-Pst

atic

)/Pst

atic

k (h/Mpc)

(32,0,64)(32,32,64)(32,64,64)(32,96,64)

Probing Symmetron with Local Power Spectrum

Llinares & DFM, PRL

Summary

} If one wants probe Modified Gravity then: } one should look at structure formation } Effects are stronger within the fifth force range and

proportional to the coupling } Nonlinear regime is the most interesting!

} If one wants to probe screening mechanisms then: } Global observables may not do the job } Only local observables with an environmental dependence can

be smoking guns