httpleandrosphysicsuoigr Department of Physics University of Ioannina Open page Accelerating Universe Geometric Observational Constraints and Growth of Perturbations Main Points Recent Geometric Probe Data SnIa CMB BAO ID: 250033
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Slide1
L. Perivolaropouloshttp://leandros.physics.uoi.grDepartment of PhysicsUniversity of Ioannina
Open page
Accelerating Universe:
Geometric Observational Constraints
and
Growth of PerturbationsSlide2
Main Points
Recent Geometric Probe Data (SnIa, CMB, BAO)
Expansion Rate of the Universe is very similar
to the rate predicted by
Λ
CDM
There are some puzzling conflicts between ΛCDM predictions and LSS cosmological observations
Q: Is there a concrete physical model where dark energy can have significant clustering properties on small scales?
Yes. This naturally occurs in Scalar-Tensor cosmologies due to the direct coupling of the scalar field perturbations to matter induced curvature perturbations
Large Scale Velocity Flows (3
σ)
Galaxy and Cluster Halo Profiles (2σ-3σ)
There is a potential resolution
of these conflicts if Dark Energy had
clustering properties. Slide3
3
Geometric Probes: Recent SnIa Datasets
Q2: What is the consistency of each dataset with
Λ
CDM?
Q3: What is the consistency of each dataset with Standard Rulers?
J. C. Bueno Sanchez, S. Nesseris, LP, JCAP 0911:029,2009,
0908.2636 Q1: What is the Figure of Merit of each dataset? Slide4
Figures of Merit
The Figure of Merit:
Inverse area of the 2
σ
CPL parameter contour. A measure of the effectiveness of the dataset in constraining the given parameters.
SNLS
ESSENCE
GOLD06
UNION
CONSTITUTION
WMAP5+SDSS5
WMAP5+SDSS7Slide5
5
Figures of Merit
The Figure of Merit:
Inverse area of the 2
σ CPL parameter contour. A measure of the effectiveness of the dataset in constraining the given parameters.
SDSS5
SDSS7
Percival et. al.
Percival et. al.Slide6
6
Consistency with Λ
CDM
ESSENCE+SNLS+HST data
SNLS 1yr data
Trajectories of Best Fit Parameter Point
The trajectories of SNLS and Constitution
are clearly
closer to ΛCDM for most values of Ω0mGold06 is the furthest from Λ
CDM for most values of Ω0mQ: What about the σ-distance (dσ
) from ΛCDM?
Ω0m=0.24Slide7
7
The σ-
distance to
Λ
CDM
ESSENCE+SNLS+HST data
Trajectories of Best Fit Parameter Point
Consistency with
ΛCDM Ranking:Slide8
8
The σ-distance to Standard Rulers
Consistency with Standard Rulers Ranking:
ESSENCE+SNLS+HST
Trajectories of Best Fit Parameter PointSlide9
Puzzles for
ΛCDM
Large Scale Velocity Flows
-
Predicted:
On scale larger than 50 h-1Mpc Dipole Flows of 110km/sec or less. - Observed: Dipole Flows of more than 400km/sec on scales 50 h
-1Mpc or larger. - Probability of Consistency: 1%
Cluster and Galaxy Halo Profiles: - Predicted: Shallow, low-concentration mass profiles - Observed: Highly concentrated, dense halos -
Probability of Consistency: 3-5%
From LP, 0811.4684R. Watkins et. al. , 0809.4041
Broadhurst et. al. ,ApJ 685, L5, 2008, 0805.2617, S. Basilakos, J.C. Bueno Sanchez, LP., 0908.1333, PRD, 80, 043530, 2009. Slide10
10
Cluster Halo Profiles
NFW profile:
Λ
CDM prediction:
The predicted concentration parameter c
vir
is significantly smaller than the observed.
From S. Basilakos, J.C. Bueno-Sanchez and LP,
PRD, 80, 043530, 2009, 0908.1333.
Data from:
Navarro, Frenk, White, Ap.J., 463, 563, 1996Slide11
11
Cluster Halo Profiles
NFW profile:
clustered dark energy
Clustered Dark Energy can produce more concentrated halo profiles
From S.
Basilakos
, J.C.
Bueno
-Sanchez and LP,
PRD, 80, 043530, 2009, 0908.1333.
Data from:
Navarro, Frenk, White, Ap.J., 463, 563, 1996Slide12
Producing Dark energy Perturbations
Q: Is there a model with a similar expansion rate as
Λ
CDM but with significant clustering of dark energy?
A: Yes. This naturally occurs in Scalar-Tensor cosmologies
due to the direct coupling of the scalar field perturbations
to matter induced curvature perturbationsSlide13
Scalar-Tensor Theories
Rescale
Φ
Units:
General Relativity:
Generalized Einstein-Field Equations:Slide14
Background Cosmological Evolution
Flat FRW metric:
Generalized Friedman equations:Slide15
Advantages and Constraints
Advantages:
Natural generalizations of GR (superstring
dilaton
, Kaluza-Klein theories) General theories (f(R) and
Brans-Dicke theories consist a special case of ST) Potential for Resolution of Coincidence Problem Natural Super-acceleration (w
eff <-1) Amplified Dark Energy Perturbations
Constraints:Solar System
CosmologySlide16
Background Evolution
J. C.
Bueno
Sanchez., LP in preparation Slide17
Minimally Coupled Quintessence
Thawing Minimally Coupled Quintessence
Slide18
Non-minimal Coupling
Oscillations (due to coupling to
ρ
m
) and non-trivial evolutionSlide19
Effective Equation of State
Effective Equation of State:
Scalar-Tensor (
λ
f
=5)
Minimal
Coupling
(λ
f=0)
w
eff
zSlide20
Perturbations: Analytical Approximations
Perturbed FRW metric (Newtonian gauge):
Generalized Einstein-Field Equations:Slide21
Analytical Approximations: Sub-Hubble ST scales
No suppression on small scales!Slide22
Analytical Approximations: Sub-Hubble GR scales
Suppressed fluctuations on small scales!
Sub-Hubble GR scales
(as in minimally coupled quintessence)Slide23
Numerical Solutions
Scalar Field Perturbations
Minimal Coupling (F=1)
Scale = 30 h
-1
Mpc
Non-Minimal Coupling (F=1-
λf2
Φ2)Slide24
Numerical Solutions
Matter Density Perturbations
Minimal Coupling (F=1)
Non-Minimal Coupling (F=1-
λ
f
2
Φ2)Slide25
Numerical Solutions
Scalar Field Density Perturbations
Minimal Coupling (F=1)
Non-Minimal Coupling (F=1-
λ
f
2
Φ2)Slide26
Numerical Solutions
Scale Dependence of Dark
Energy/Dark Matter
Perturbations
Minimal Coupling (F=1)
Non-Minimal Coupling (F=1-
λ
f Φ2
)
Dramatic Difference on sub-Hubble scales!Slide27
Numerical Solutions
Scale Dependence of Dark Energy Perturbations
Minimal Coupling (F=1)
Non-Minimal Coupling (F=1-
λ
f
Φ2)
Dramatic Difference on sub-Hubble scales!Slide28
SUMMARY
Recent Geometric Probe Data (SnIa, CMB, BAO
)
are increasingly consistent with
Λ
CDM and with each other. The Constitution SnIa dataset is of the highest quality and is also the most consistent with ΛCDM and with Standard
Rulers.Observed Cluster Halo Profiles
are significantly more concentrated than predicted by ΛCDM. This may be interpreted as a trace of an additional clustering energy component in the halo.
Scalar Tensor cosmologies are generic extensions of GR. They naturally allow for crossing of the w=-1 line and amplified dark energy perturbations on sub-Hubble scale by a factor of more than 104
compared to quintessence. This may help in the resolution of the cluster profile puzzle.