Observational test of modified gravity models with future imaging surveys. Kazuhiro Yamamoto (Hiroshima U.). K.Y. , Bassett, Nichol, Suto, Yahata, (PRD 2006) K.Y. , Parkinson, Hamana, Nichol, Suto, (PRD 2007) Discussion by HSC Weak Lensing Working Group. Edinburgh Oct. 24-26. 2. - PowerPoint PPT Presentation
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Observational test of modified gravity modelswith future imaging surveys
Kazuhiro Yamamoto (Hiroshima U.)
Edinburgh Oct. 24-26
K.Y. , Bassett, Nichol, Suto, Yahata, (PRD 2006)K.Y. , Parkinson, Hamana, Nichol, Suto, (PRD 2007)Discussion by HSC Weak Lensing Working Group
INTRODUCTION
Modified Gravity models as alternative to the dark energy
f(R) gravity model, TeVeS theory, DGP model, etc. ・・・
ambitious challenges to the fundamental physics necessary step to go beyond the standard model ?
All these models may not be complete, but are
A lot of observational projects of the dark energy are proposed,
These results might be useful to test modified gravity theory.
WFMOS, HSC, DES, DUNE, LSST, JDEM, BOSS, ・・・
Future feasibility of testing gravity models ?Optimized strategy of future survey of HSC ?
2
Investigation of the observational consequences of typical model is thought-provoking, because we can learn what can be possible signatures of such generalized gravity models.
The DGP model as an example (Dvali, Gabadadze, Porrati, 00)
Brane world scenario, (3+1)-dim brane in (4+1)-dim. bulk
It is possible to construct a self-accelerating universe, without introducing dark energy, by choosing a scale parameter, rc=M4
2/2M52,
defined by the ratio of the Planck scales, properly.
(Deffayet, 01)
Modified Friedmann equation (flat universe)
mc
2 ρ3
8π=
r
H-H
G
Modification of expansion history changes the distance redshift relation
z
zH
dzz
0 )'(
')(
3
can be tested using SNe, BAO, CMBModified relation of the background expansion, distance-redshift relation
(K.Y., Bassett, Nichol, Suto, Yahata)
(e.g., Maartens, Majerroto 06)
Constraint using Baryon Oscillation
4
dlnP(k)/dlnk The Λ-model and the DGP model the same cosmological parameter and the same data analysis,
Area 2000 deg2
n = 5×10-4 (h-1Mpc)-3
0.5 < z < 1.3
WFMOS-like sample
One can distinguish between the Lambda model and the DGP model clearly
difference of H(z) and r(z), the peaks shift.
The background expansion is parameterized in general (flat universe)
z1
z3w)ww3(1
m3m2
02 ez))(1Ω-(1
z)(1Ω
HH(z) 0a
a
The expansion history of the DGP model is reproduced by the dark energy model of the equation of state
z1z
0.32-0.78w(z)
Ωm ~ 0.3
The expansion history of M.G. can be described equivalently by the parameterization of the dark energy model.
z1z
www(z) 0 a
(Linder, 04)
5
Perturbation is important as an independent information
(Maartens, Koyama 06)Perturbation of the cosmological DGP model
)sin(21)(21 22222222 dddtadtds
022
2
2
2
a
k
dt
dH
dt
d
mGak
3
114 22
maG
k 22
3
8
23121
HHHrc
mGak 22 8
Evolution of Growth factor
Modified Poisson equation
Anisotropic stress
(sub-horizon sclale)
6
Evolution of Growth factor
ΛCDM
DGP Dark Energy
Same expansion H(z)
a
aD )(1
a
growth factor is important to distinguish between the gravity models.
7
Phenomenological description of the perturbation for generalized gravity models
Feasibility of measuring γ with the HSC Weak Lens survey?
Fisher Matrix Analysis
a
0 m1 1-)(a'Ω
a'da'
expa(a)D γGrowth of density perturbation
Background expansion
1)-(a3w)ww-3(1m
-3m
20
2 e)aΩ-(1aΩHH(a) 0 aa
a)-(1www(a) 0 a
Analysis in the 7 parameters space
sma nhww ,,,,, 80 γ
marginalized
flat universe, Assumption;
13
β0
0
)(z/z-α1)/β)+Γ((αz
βg ezN=
dz
dN(z)1+α
3=β50=α ,.
dz
dNdzz
N
1=z ∫
gm
dz
dNdz=N ∫g
)/( 38Γ
z=z m
0
067.0
.min30exp9.0t
meanz
( )440
30
t
g 30=N.
.minexp
Amara & Refregier (06)
arcmin-2
(SNAP simulation)
(number density arcmin-2)
(mean redshift)
expt exposure time
Modeling of Galaxy distribution
/ 1 Field of View / 1 passband filter
The Validity of this relation for the HSC is now investigated by WLWG.
14
operationtnt
1.1
n timeobservatio Total
passbandnumberexp
2
2ViewofFieldArea
Total observation time = 100 nights (fixed)
Field of view = 1.5 degree
Overheard time = 10% of exposure time + operation time (toperation=5 minutes)
expt (one band exposure time for one FoV)
Total survey area
Assumption of the HSC WL survey
4passbandnumber n
15
Total survey area=1700 deg.2 texp=10mins./1FoV/passband
Total survey area as a function of texp
Total observation time = 100 nights4 passband filters
16
1σ error as a function of texp
Constraint on γ from the WL shear power spectrum
photo-z error
)1(05.0 zz
5.105.0 z only used the sample
The observation of 100 nights will be difficult to achieve
1.0
17
Marginalized Fisher matrix
Constraint on γ from the WL shear power spectrum + galaxy power spectrum (BAO) from WFMOS like spectroscopy survey
1σ error as a function of texp
34 Mpch10×4=n ]/[-
4.18.0 z
Assumed additional spectroscopy survey of the same survey area as the WL survey
of the number density
in the redshift range
Combination with the WFMOS improves the constraint 07.0
WL + BAO
18
Summary & Conclusion
Dark energy survey is useful to test modified gravity models
Simple consistency test is to measure γ parameter
The weak lensing method is useful to constrain γ
The HSC alone would not provide a strong constraint, but the combination with the WFMOS improve it, and Δγ≦0.07 might be possible. (2σ level for differentiating between the DE and the DGP) Slightly depends on the modeling of the galaxy count, dN/dz