Dark Energy Dark Energy The first Surprise in The first Surprise in the era the era of precision of precision cosmology?cosmology?

Dark Energy Evidence Dark Energy Evidence

Dark Energy Evidence Dark Energy Evidence

Percival et al. MNRAS Percival et al. MNRAS 327 1297 2001327 1297 2001

Dark Energy Evidence Dark Energy Evidence

WMAP+ACBAR+CBI+2dF+LymanWMAP+ACBAR+CBI+2dF+Lyman

4%4%

Cosmological Constant Problem Cosmological Constant Problem

GG=8=8 T T

Cosmological Constant Problem Cosmological Constant Problem

GG+ + gg=8=8 T T ++VVgg

Geometry Geometry

Quantum VacuumQuantum Vacuum

Cosmological Constant Problem Cosmological Constant Problem

||-V|/M-V|/M44PlanckPlanck 1010-120-120

::

V:V:

for Physics for Physics

Why so small Why so small with respect to with respect to

any particle any particle physics scalephysics scale

Why Why comparable comparable

to the to the cosmological cosmological

matter matter density todaydensity today

Two Two

Dark Energy Models Dark Energy Models • Trans PlanckianTrans Planckian: : energy stored in perturbation modes energy stored in perturbation modes on super-horizon scales (Mersini et al., PRD64 043508, 2001)on super-horizon scales (Mersini et al., PRD64 043508, 2001)• Spacetime microstructureSpacetime microstructure: self-adjusting spacetime capable : self-adjusting spacetime capable to absorbe vacuum energy (Padmanabhan, gr-qc/0204020)to absorbe vacuum energy (Padmanabhan, gr-qc/0204020)• Matter-Energy TransitionMatter-Energy Transition: dark matter converts to dark energy at: dark matter converts to dark energy atlow redshifts (astro-ph/0203383)low redshifts (astro-ph/0203383)• Brane worldsBrane worlds: brane tension (Shani & Sthanov astro-ph/0202346);: brane tension (Shani & Sthanov astro-ph/0202346);cyclic-ekpyrotic cosmic vacuum (Steinhardt &Tutok hep-th/0111098)cyclic-ekpyrotic cosmic vacuum (Steinhardt &Tutok hep-th/0111098)

• Quintessence: tracking scalar fields (Steinhardt, Wang & Zlatev, PRD59, 123504, 1999; Ratra & Peebles, Wetterich 1988)• Extended Quintessence: non-minimal coupling to Gravity (Uzan Chiba, Perrotta, Baccigalupi, Matarrese, PRD61, 023507, 2000• Coupled Quintessence: coupling with dark matter (Amendola, Pietroni...)

Quintessence Field Quintessence Field

(t)+(t)+(t,x), U((t,x), U())

Effects on the CMB Effects on the CMB • ProjectionProjection• Integrated Sachs-WolfeIntegrated Sachs-Wolfe

Quintessence & CMB: wQuintessence & CMB: w,,

Baccigalupi et al. 2002Baccigalupi et al. 2002

Quintessence & CMB: wQuintessence & CMB: w,,

Quintessence & CMB: bispectrum Quintessence & CMB: bispectrum

Giovi et al. 2003, in preparation Giovi et al. 2003, in preparation

Quintessence & Large Scale StructureQuintessence & Large Scale Structure

Aperture Mass Statistics: Bartelmann, Perrotta, Baccigalupi 2002 Aperture Mass Statistics: Bartelmann, Perrotta, Baccigalupi 2002

Halo Concentration: Bartelmann et al. A&A 2002 Halo Concentration: Bartelmann et al. A&A 2002

Growth Factor, Transfer Function: Ma et al. 1998Growth Factor, Transfer Function: Ma et al. 1998

N-body: Maccio’ et al. 2003 N-body: Maccio’ et al. 2003

Extended Quintessence Extended Quintessence kk

22=4=4 k k33(( / /))kk22

Perrotta, Baccigalupi, Matarrese 2000, Perrotta & Baccigalupi 2002 Perrotta, Baccigalupi, Matarrese 2000, Perrotta & Baccigalupi 2002

mm

cc22eff, eff, 11

GravityGravity

ConclusionsConclusions•DiscoveryDiscovery•Concerning Vacuum Concerning Vacuum EnergyEnergy

•Observable, Here and Now!Observable, Here and Now!•Probes: WMAPext+LSS, Probes: WMAPext+LSS, LSST, Planck, SNAPLSST, Planck, SNAP

Dark Energy Dark Energy