Dark Energy vs. Dark MatterDark Energy vs. Dark Matter

Towards a unification…Towards a unification…

Centre de Recherche Astronomique de LyonCentre de Recherche Astronomique de Lyon

Alexandre ARBEY

March 5, 2006

The Dark Side of the UniverseThe Dark Side of the Universe• Galactic Scale

Striking problems arrive from the Galaxy Rotation Curves.

• Clusters ScaleAt this scale, the existence of a great amount of non-visible matter can be deduced from cluster gas and weak lensing observations.

90 % of the effective matter is invisible !

Same conclusions !• Cosmological Studies

Different studies enable to know the proportions of baryonic and non-baryonic matters in the global energy of the cosmic fluids.30 % of the total Energy in the Universe is

Matter.

15 % of this Matter is baryonic.

70 % of the total Energy in the Universe is unknown !

2

Usual Description of the Usual Description of the UniverseUniverse

Components:

Radiation: photons, neutrinos

Baryonic matter

Dark Matter: WIMPS, axions…

Dark Energy: cosmological constant, quintessence…

Other: inflaton, vacuum energy…

SCP

3

Dark Matter vs. Dark Dark Matter vs. Dark EnergyEnergy

Tradition

WIMPS models seem OK

Cosmological Constant could be OK

WIMPS have never been detected

Some other problems remain with WIMPS

Nature of Dark Energy

Observations tend to show:1Energy Dark

P

Why 2 components?

Problems and Questions

Non-usual models

4

Dark Fluid ?Dark Fluid ?One unique fluid to replace Dark Matter and Dark Energy

Today:

Matter behaviour at local scales.

Repulsing behaviour at cosmological scales.

Early Universe:

Matter behaviour at all scales.

Constraints

Advantages

One unique Dark Fluid instead of two.

Can lead to a High Energy Physics Theory. 1fluid dark

5

6

Towards a unification ?Towards a unification ?

Supernovae of Type IaSupernovae of Type Ia

Structure formationStructure formation

Big-Bang NucleosynthesisBig-Bang Nucleosynthesis

6.00.1

25.076.0

08.096.0

1

0

0

03/1 .. fs

3/1BBN

P

Equation of state:Equation of state: Low redshift:Low redshift: 10)( zz

A. Arbey, astro-ph/0506732

BBNrad

BBN or

Scalar Fields…Scalar Fields…Appear in:

Particle Physics: Spin 0 particles, Higgs field

High Energy Physics: Unification Theories

Cosmology: Quintessence, Inflation

)( VgL

)V( P 2

2

1

)V( 2

2

1

PgUUPLgT )(

03

V

H

Difficulty: Never observed…

7

Scalar Fields as Dark EnergyScalar Fields as Dark EnergyQuintessence

radiation

matter

Inverse Power Law

“SUGRA”

Inverse Power Law

“SUGRA”

nV

V

V

]1)[cosh()(

)exp()(

)(

P

8

Scalar Fields as Dark Scalar Fields as Dark MatterMatter

4a 3a

)(

2tie

Internal rotation: 42

2)( mV

22)( mV

(Complex scalar field)

9

A. Arbey et al., astro-ph/0105564,

astro-ph/0112324, astro-ph/ 0301533.

10

Homogeneous vs. Homogeneous vs. InhomogeneousInhomogeneous

02

1)3(

2

1 galaxiesgalaxiesgalaxiesgalaxies00 PS Attractive inside

structures

),()( ),( cosmo rttrt

0),( rtwit

h),()( ),( cosmo rtPtPrtP

0),( rtP

wit

h329

0cosmo .109)( cmgt

32400

WayMilky .105),( cmgrt

cosmogalaxies

0)3(2

1 space emptyspace emptyspace empty00 PS Repulsive in empty

space

0space empty00

space empty00

galaxies00

cosmo00 SSSS

Repulsive on cosmological scales

seems possible to unify both visions !

Scalar Field as Dark Fluid ?Scalar Field as Dark Fluid ?

)(* VgL

n

-B

B

BAmV

AmV

AmV

])[cosh()(

e)(

)(

Φ

122

22

22

Local scales Cosmological scales

Complex scalar field

Superposition of potentials

11

Promissing potential ?Promissing potential ?222 Φe)( -BAmV

Local scales

(galaxies)

Cosmological scales

12

Local scales

(clusters)

eV2310m

energydarkA 0

22210 eVB

Some results…Some results…

13

ConclusionsConclusions

14

Unifying Dark Fluids can be compatible with observations

Many constraints on the models:

- constraints on the matter behaviour

- constraints on the dark energy behaviour

- inhomogeneous modelization: local vs. global

Examples of possible Dark Fluids:

- Scalar fields with specific potentials

- Chaplygin Gas, … ?

More tests needed