L. Perivolaropouloshttp://leandros.physics.uoi.gr

Department of Physics

University of Ioannina

Open page

S. Nesseris, LP, astro-ph/0610092, astro-ph/0611238

40

0 0

5 10G

G H

02

0 0

1.91G

G H

Observational Probes of the Accelerating Expansion

w(z) is close to -1 w(z) crossing the w=-1

w(z) crossing the w=-1

Inconsistent with Minimally Coupled Quintessence

and also with Scalar Tensor Quintessence

if G(t) is increasing with time.

Marginal Consistency of Scalar-Tensor Quintessence withObserved Accelerating Expansion

40

0 0

5 10G

G H

02

0 0

1.97G

G H

Maximal Agreement of Scalar-Tensor Quintessence

with the Full Parameter Range of Observed Acelerating Expansion

G(t) can not increase rapidly with t

(not ‘sharp’ Maximum)

Close to Extremum (Solar System)

G(t) decreases with t (close to a Minimum)

Close to Extremum (Solar System)

SNLS

SNLS

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

)(zw

z

0

02 2

min

2 2min

1 2

: 1 2

1 2

: 1 21 2

1 2

2min

; , ,...,

; , ,...,

; , ,...,

; , ,...,, ,...,

; , ,...,

z

z

obsL i

obsL i

dz

n

dzData d zth

L n

n

Data d z L nn

n

Physical Model H z a a a ansatz

d z a a a

H z a a a

d z a a aa a a

w z a a a

1 2, ,..., na a a

2min 171.7OA

LCP

2min 177.1CDM

0.3m

• All best fit parameterizations cross the phantom divide at z~0.25

• The parametrization with the best χ2 is oscillating

Lazkoz, Nesseris, LP 2005

Trunc. Gold (140 points, z<1) Full Gold (157 points, z<1.7)SNLS (115 points z<1)

SNLS data show no trend for crossing the phantom divide w=-1!

0.24m z

zwwzw

1)( 10

S. Nesseris, L.P. Phys. Rev. D72:123519, 2005

astro-ph/0511040

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

0 0.2m

Gold datasetRiess -et. al. (2004)

SNLS datasetAstier -et. al. (2005)

Other data:CMB, BAO, LSS, Clusters

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

S. Nesseris, L.P. astro-ph/0610092

)(zw Other data:CMB, BAO, LSS, Clusters

z z z

2

300

2 ln1 1( ) 3

( )1 1

DE

DEm

d Hzp z dzw z

z Hz

H

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

Gold datasetRiess -et. al. (2004)

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

SNLS datasetAstier -et. al. (2005)

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

0 0.25 0.5 0.75 1 1.25 1.5 1.75

1.5

1

0.5

0

0.5

1

1.5

Other data:CMB, BAO, LSS, Clusters )(zw

z z z

0 0.3m

z

zwwzw

1)( 10

Minimize:

2 2 2 21 2 1 2 1 2 1 2

22 2 226

1 21 2 1 2 1 2

2 2 2 21

, , , , , ,

; ,, , 1.70 , , 0.469 0.15; , 0.51

0.03 0.017 0.11

CMB m BAO m cl LSS

SCDMgas i gas im m

i gas i

w w w w w w w w

f z w w fR w w A w w g z w w

0 0.2m

11.051.0)(

)('15.01

1

aD

aaD

azg

Eisenstein et. al. 2005Wang, Mukherjee 2006

Allen et. al. 20042dF:Verde et. al.

MNRAS 2002

0 0.2m

0 0.3m

0.2mCMB BAO Clusters LSS

0.3mCMB BAO Clusters LSS

Riess et. al. astro-ph/0611572

Old Gold Filtered Gold+New HST Filtered Gold+New HST+Best of SNLS

S. Nesseris, LP in prep.

Old Gold Filtered Gold+New HST Filtered Gold+New HST+Best of SNLS

Q1: What theories are consistent with range of observed H(z)?

• Cosmological Constant

• Quintessence

• Extended (Scalar–Tensor) Quintessence

• Braneworld models (eg DGP)

• Barotropic fluids (eg Chaplygin Gas)

Q2: What forms of H(z) are inconsistent with each theory? (forbidden sectors)

Q3: What is the overlap of the observationally allowed range of H(z)

with the forbidden sector of each theory?Goal: Address Q2-Q3 for Extended Quintessence

Plausibility Arguments+

Numerical Simulations

Caldwel, Linder 2005

V(Φ)

Φ

V(Φ)

Φ

ThawingThaw Accelerate

FreezingDecelerate Freeze

3dU

Hd

2 28 1

3 2m

GH U

p,

21

2 m mH p F HFF

2 21 13

3 2mH U HFF

dz

d'

Consistency Requirements:

Express Fi in terms of G(t) current time derivatives:

Ignored :1g (Solar System Tests, Pitjeva 2005)

Gannouji, Polarski, Ranquet, Starobinsky astro-ph/0606287

2

0 0zz

Freezing

2

0 0zz Thawing

10 0U z U

2

0 0zz

Freezing

2

0 0zz Thawing

10 0U z U

Lower bound on g2:

Chevallier-Polarski-Linder

Lower bound on g2: Upcoming Solar System Constraints on g2:

5 529 10 10g J. Mueller 2006

Chevallier-Polarski-Linder

2 0 implies decreasing G which helps

boost accleration beyond the w=-1 barrier

g

2Why does 0 shrink the forbidden sector beyond the w=-1 limit?g

SnIa Absolute Luminosity:

Steps of Analysis:

1. Assume G(z) parametrization consistent with Solar System + Nucleosynthesis bounds

2. Consider modified magnitude-redshift relation

3. Minimize χ2

The shift of the contours is not significantcompared to the area of the contours.

40

0 0

10G

G H

02

0 0

1.91G

G H

Observational Probes of the Accelerating Expansion

w(z) is close to -1 w(z) crossing the w=-1

w(z) crossing the w=-1

Inconsistent with Minimally Coupled Quintessence

and also with Scalar Tensor Quintessence

if G(t) is increasing with time.

Consistency of Scalar-Tensor Quintessence

Observed Accelerating Expansion

40

0 0

10G

G H

02

0 0

1.97G

G H

Maximal Agreement of Scalar-Tensor Quintessence

with the full range of observed Acelerating Expansion

G(t) can not increase rapidly with t

(not ‘sharp’ Maximum)

Close to Extremum (Solar System)

G(t) decreases with t (close to a Minimum)

Close to Extremum (Solar System)