Transcript Accelerating Universe

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L. Perivolaropoulos
http://leandros.physics.uoi.gr
Department of Physics
University of Ioannina
Recent Geometric Probe
Data (SnIa, CMB, BAO)
There are some puzzling conflicts
between ΛCDM predictions and
LSS cosmological observations
There is a potential resolution
of these conflicts if Dark Energy had
clustering properties.
Expansion Rate of the Universe is very similar
to the rate predicted by ΛCDM
Large Scale Velocity Flows (3σ)
Galaxy and Cluster Halo Profiles (2σ-3σ)
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
Q1: What is the Figure of Merit of each dataset?
Q2: What is the consistency of each dataset with ΛCDM?
Q3: What is the consistency of each dataset with Standard Rulers?
J. C. Bueno Sanchez, S. Nesseris, LP,
JCAP 0911:029,2009, 0908.2636
3
The Figure of Merit: Inverse area of the 2σ CPL parameter contour.
A measure of the effectiveness of the dataset in constraining the given
parameters.
6
SNLS
4
w1
0
UNION
4
4
2
2
0
0
2
2
2
2
4
4
4
4
6
6
6
6
1.5
1.0
0.5
0.0
2.0
1.5
1.0
w0
6
0.0
2.0
1.5
1.0
2
2
0
4
6
w1
2
4
1.5
1.0
w0
w0
0.5
0.0
1.0
0m  0.28
6
1.5
1.0
w0
0.5
0.0
w( z )  w0  w1
4
2.0
0.5
0
2
6
2.0
1.5
WMAP5+SDSS7
4
2
2.0
6
4
2
0.0
w0
WMAP5+SDSS5
4
0
0.5
w0
6
CONSTITUTION
w1
0.5
w0
w0
w1
2.0
w1
w1
0
w1
2
6
GOLD06
ESSENCE
4
2
w1
6
w1
6
0.0
2.0
1.5
1.0
w0
0.5
0.0
z
1 z
The Figure of Merit: Inverse area of the 2σ CPL parameter contour.
A measure of the effectiveness of the dataset in constraining the given
parameters.
SDSS5
SDSS7
Percival et. al.
Percival et. al.
5
Trajectories of Best Fit Parameter Point
ESSENCE+SNLS+HST data
Ω0m=0.24
SNLS 1yr data
The trajectories of SNLS and Constitution are clearly closer to
ΛCDM for most values of Ω0m
Gold06 is the furthest from ΛCDM for most values of Ω0m
6
Q: What about the σ-distance (dσ) from ΛCDM?
ESSENCE+SNLS+HST data
Trajectories of Best Fit Parameter Point
Consistency with ΛCDM Ranking:
7
ESSENCE+SNLS+HST
Trajectories of Best Fit Parameter Point
Consistency with Standard Rulers Ranking:
8
From LP, 0811.4684
Large Scale Velocity Flows
R. Watkins et. al. , 0809.4041
- 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:
Broadhurst et. al. ,ApJ 685, L5, 2008, 0805.2617,
S. Basilakos, J.C. Bueno Sanchez, LP., 0908.1333, PRD, 80, 043530, 2009.
- Predicted: Shallow, low-concentration mass profiles
- Observed: Highly concentrated, dense halos  cvir ~ 10 15
- Probability of Consistency: 3-5%
 cvir ~ 4  5
Navarro, Frenk,
White, Ap.J., 463,
563, 1996
NFW profile:
From S. Basilakos, J.C. Bueno-Sanchez and LP,
PRD, 80, 043530, 2009, 0908.1333.
1.2
1.0
ΛCDM prediction:
c
c1  c2
rvir
rs
0.8
0.6
c1
0.4
0.2
c2
0.0
4
2
0
2
4
The predicted concentration parameter cvir is significantly
smaller than the observed.
Data from:
10
Navarro, Frenk,
White, Ap.J., 463,
563, 1996
From S. Basilakos, J.C. Bueno-Sanchez and LP,
NFW profile:
PRD, 80, 043530, 2009, 0908.1333.
clustered dark energy
1.2
1.0
c
c1  c2
rvir
rs
0.8
0.6
c1
0.4
0.2
c2
0.0
4
2
0
2
4
Clustered Dark Energy can produce more concentrated halo
profiles
Data from:
11
Q: Is there a model with a similar expansion rate as ΛCDM 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 perturbations
 m , pm 
Rescale Φ
Z    1
General Relativity:
Generalized Einstein-Field Equations:
Units:
8 G  1
Flat FRW metric:
Generalized Friedman equations:
tot  ptot
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 (weff <-1)
• Amplified Dark Energy Perturbations
Constraints:
Solar System
Cosmology
F, 2
F
F, 2
F
 104
t  t0
 O 1
J. C. Bueno Sanchez., LP in preparation
0m  0.3
 f  0,   1, i  0.12
Thawing Minimally
Coupled Quintessence
F    1   f 2
 f  5,   1, i  0.12
Oscillations (due to coupling to
ρm ) and non-trivial evolution
Effective Equation of State:
1 2
  U     F  2 HF
p 2
weff  z  

1 2

  U     3HF
2
Scalar-Tensor (λf=5)
weff
Minimal Coupling (λf=0)
z
Perturbed FRW metric (Newtonian gauge):
Generalized Einstein-Field Equations:
F,   1
k
 H
a
No suppression on small scales!
Sub-Hubble GR scales
k
 H
a
F,  1
F,
k
 H
a
k
 H
a

F,  1
F,
k
 H
a
H 2 a2
A
0
2
k
Suppressed fluctuations on small scales!
(as in minimally coupled quintessence)
Scalar Field Perturbations
 f  0,   1, i  0.12
Minimal Coupling (F=1)
Scale = 30 h-1 Mpc

H 2 a2
10 
0
2
k
 f  5,   1, i  0.12
Non-Minimal Coupling (F=1-λf2 Φ2)
Matter Density Perturbations
 f  0,   1, i  0.12
Minimal Coupling (F=1)
 f  5,   1, i  0.12
Non-Minimal Coupling (F=1-λf2 Φ2)
Scalar Field Density Perturbations
 f  0,   1, i  0.12
Minimal Coupling (F=1)

A H  δΦ
2
H 4 a2
10  
0
k2
2
 f  5,   1, i  0.12
Non-Minimal Coupling (F=1-λf2 Φ2)
Scale Dependence of Dark Energy/Dark Matter Perturbations
 f  0,   1, i  0.12
Minimal Coupling (F=1)
 f  5,   1, i  0.12
Non-Minimal Coupling (F=1-λf Φ2)
Dramatic Difference on sub-Hubble scales!
Scale Dependence of Dark Energy Perturbations
 f  0,   1, i  0.12
Minimal Coupling (F=1)
 f  5,   1, i  0.12
Non-Minimal Coupling (F=1-λf Φ2)
Dramatic Difference on sub-Hubble scales!
Recent Geometric Probe Data (SnIa, CMB, BAO) are
increasingly consistent with ΛCDM 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.