Licia Verde

University of Pennsylvania

www.physics.upenn.edu/~lverde

Connecting cosmology to fundamental physics

Cosmological data* can be used to test fundamental physics

The interplay between astrophysics and fundamental physics has already produced spectacular findings (e.g. the solar neutrino problem)

Cosmology has entered the precision era very recently

Testing fundamental physics by looking up at the sky is not new

*For now, CMB is the cleanest probe we have

4 Areas

Dark matter (Spergel talk)

Neutrinos (Spergel talk)

Inflation

Dark energy

Outline:

Precision Cosmology: examples

Inflation: what have we learned, prospects for the future

Dark energy: what we have learned, prospects for the future

Conclusions

When things do not make sense… invoke a scalar field…

Cosmology has a standard model: What have we learned?

If you see the glass half empty:

If you see the glass half full:

Bennett et al 2003

COBE 1992

WMAP 2003

Bennett et al. 1996

Today

2dFGRS

SDSS here

SDSS

Hot and cold spots Tiny ripples in density seeds of galaxies

Detailed statistical properties of these ripples tell us a lot about the UniverseWMAP view of the primordial fireball

Bond Efstathiou 1987

Hot and cold spots Tiny ripples in density seeds of galaxies

Detailed statistical properties of these ripples tell us a lot about the UniverseWMAP view of the primordial fireball

Matter overdensities compress cosmic fluids through gravity

Photons (tightly coupled to the baryons) counteract this

Sound speed is high (photon/baryon high) cs=c/3 1/2

Sound horizon cst defines a maximum size

Acoustic oscillations set in

Damping: photons free streaming, finite thickness of LSS

Phase correlation:structures of a given size start oscillating together

What’s going on

Work of Peebles & Yu, Sunyaev & Zeldovich ‘70

(From Hinshaw et al 2003)

Status in early 2003

Approximation to the state of the art now

WMAP1 + CBI + ACBAR+ CBI05+ Boomerang 05+VSA

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2 10 100 1000

Approximation to the state of the art now

WMAP1 + CBI + ACBAR+ CBI05+ Boomerang 05+VSA

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Primordial ripples

Fundamental mode

1 deg

compression

rarefactioncompression

Acoustic peaks(extrema)

Primordial ripples

Fundamental mode

Geometry

Potential wells

mΩ

compression

baryons

Rarefaction… etc

Jungman, Kamionkowski, Kosowsky, Spergel, 1996

+primordial perturbations

Generation of CMB polarization

• Temperature quadrupole at the surface of last scatter generates polarization.

Potential wellPotential hill

From Wayne Hu

Rees 68, Coulson et al ‘94….. Hu& White 97(pedagogical)

YES, there is also reionization

Polarization for density perturbation

• Radial (tangential) pattern around hot (cold) spots.

Image from J. Rhul.

Image from J. Rhul.

E and B modes polarization

E polarization from scalar, vector and tensor modes

B polarization only from (vector) tensor modes

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Kamionkowski, Kosowsky, Stebbings 1997, Zaldarriga & Seljak 1997

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Inflation

V()

H ~ const

Solves cosmological problems (Horizon, flatness).

Cosmological perturbations arise from quantum fluctuations, evolve classically.

Guth (1981), Linde (1982), Albrecht & Steinhardt (1982), Sato (1981), Mukhanov & Chibisov (1981), Hawking (1982), Guth & Pi (1982), Starobinsky (1982), J. Bardeen, P.J. Steinhardt, M. Turner (1983), Mukhanov et al. 1992), Parker (1969), Birrell and Davies (1982)

Flatness problem

Horizon problem

Structure Problem

WMAP Consistent with Simplest Inflationary Models

• Flat universe: Ωtot = 1.02 ± 0.02

• Gaussianity: -58 < ƒNL < 134

• Power Spectrum spectral index nearly scale-invariant:

ns = 0.99 ± 0.04 (WMAP only)

• Adiabatic initial conditions

• Superhorizon fluctuations (TE anticorrelations)

WMAP TE data in bins of l=10

Primordial Adiabatic i.c.

Causal Seed model (Durrer et al. 2002)

Primordial Isocurvature i.c.

(Peiris et al. 2003)

Hu & Sujiyama 1995Zaldarriaga & Harari 1995Spergel & Zaldarriaga 1997

1. Primordial B-mode anisotropy

– Inflation-generated gravity waves (tensor modes) polarize CMB

– (Kamionkowski & Kosowski 1998)

– A “smoking gun” of inflation => holy grail of CMB measurements

– At least an order of magnitude smaller than E-mode polarization

Gravity Waves in the CMB Inflation produces two types of perturbations: in the energy density ( as seen in TT) and in the gravitational field (gravity waves). Unlike temperature anisotropy, CMB polarization anisotropy can discriminate between scalar modes (density perturbations) and tensor modes (gravity waves). (r=tensor to scalar ratio)

Information about the shape of the inflaton potential is enclosed in the shape and amplitude of the primordial power spectrum of the perturbations.

Information about the energy scale of inflation (the height of the potential) can be obtained by the addition of B modes polarization amplitude.

In general the observational constraints of Nefold>50 requires the potential to be flat (not every scalar field can be the inflaton). But detailed measurements of the shape of the power spectrum can rule in or out different potentials. For example: Kahler inflation towards the KKLT minimum, or for multi-field other minima

Seeing (indirectly) z>>1100

Primordial power spectrum=A kn

Amplitude of the power lawslope

ln k

ln P(k) A(convention dependent)

!

Running of the spectral indexkd

dn

ln

nAkkP =)(

)()( knAkkP =

generalize

Taylor expand

0

lnln2

1)(

00 )()(

k

k

kd

dnkn o

k

kkAkP

+

⎟⎟⎠

⎞⎜⎜⎝

⎛=

kd

Pdn

ln

ln=

pivot

kln

d ln

P/d

ln k

)( α=

=0

>0

<0

α

“Generic” predictions of single field slow roll models

Monte Carlo simulations following Kinney (2002) and Easther and Kinney (2002)

Each point is a “viable” slow roll model, able to sustain inflation for sufficient e-foldings to make the universe flat.

(hybrid)

(Peiris et al. 2003)

WMAP Constraints on Inflationary Models

4λφ

4λφ

Negative curvature (e.g.: new inflation)

Small positive curvature (e.g.: chaotic inflation, extended inflation)

Intermediate positive curvature

Large positive curvature (e.g.: hybrid inflation)

Recommended: For given model, sit on that point and run likelihood analysis (may need to integrate mode equation directly).

lf4 model:

Not in such a good shape…..

(From Peiris et al. 2003)

See also Kinney et al. (2003)

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Leach & Liddle 03

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Barger et al 03

CMB only

With LSS

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The inflaton potential

Kinney et al 2003

Prospects for the future:

Better shape of the primordial power spectrum:

WMAP II (more data, and breaking degeneracies)

Planck

ACT

A:

Probing smaller scales?

Large-scale structure?

The CMB can also be used to measure large-scale structureACT: The Atacama Cosmology

Telescopewww.hep.upenn.edu/act

Toronto

Princeton

Penn

CUNY

Columbia

Haverford

U Mass

P.I. Lyman Page

Region of the sky covered by ACT

Strip of 2.5 degrees in width

Courtesy of Carlos Hernandez-Monteagudo

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B: Prospects for B Modes measurements

CMBCMB+H prior (HST Key project)

SN 1A

LSS

Dark EnergyD

AR

K E

NE

RG

Y…

.

(Riess et al 04)

(WMAP ext ‘03)

(2dF Verde et al 02)

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What have Supernovae observations shown?

From Riess et al 04

W ?

With new SN data (Riess et al. 2004)WMAP

With new SN data (Riess et al. 2004)WMAP

H prior from HST key project

With 2dF (LSS)

But, why constant?

Assuming a flat Universe….

But, why w constant? Why flatness?

+CFHTLSSembloni et al 05

CTIO +CMB+SN

Jarvis et al 05

(75 sq degrees, no redshifts)

(3 sq degrees)

Baryon oscill. SDSSEisenstein et al. 05

Constraints on QUINTESSENCE

Keeping flatness and power law P(k)

Galaxy surveys

THE SYMPTOMSOr OBSERVATIONAL EFFECTS of DARK ENERGY

Recession velocity vs brightness of standard candles: dL(z)

CMB acoustic peaks: Da to last scattering

LSS: perturbations amplitude today, to be compared with CMB (or Matter density today)

Da to zsurvey

HOW TO MAKE A DIAGNOSIS?

combination of approaches!

Any modification of gravity of the form of f( R ) can be written as a quintessence model for a(t)

This degeneracy is lifted when considering the growth of structure

Effort in determining what the growth of structure is in a given Dark Energy model!

COMPLEMENTARITY IS THE KEY!

The questions we want to ask:

Is it a cosmological constant?A rolling scalar field? A fluid?Is it a w= -1? w(z)?

Is it a breakdown of GR at horizon scales?

Measurements of the growth of cosmological structures will help to disentangle the two cases.

For not mentioning: control of systematics!

Backreaction…

Example:

Things could be “going wrong” in other ways

We can “measure” dark energy because of its effects on the expansion history of the universe and the growth of structure

SN: measure dL

CMB: A and ISW a(t)LSS or LENSING: g(z) or r(z) a(t)

AGES: H(z) a(t)

''

)'1()1(0

dzdz

dtzzd

z

L ∫ ++=

dt

dz

zzH

ta

ta

)1(

1)(

)(

)(

+−==

&

θ

)]0(/)([022 ρρ zHH =

QQ zwzH ρρ ))(1)((3 +−=&

∫ +Ω+Ω+−=−

z

QQm wz

dzz

dt

dzH

0

2/12/510 ]}

)'1(

'3exp[)0()0({)1(

Growth of structure: clusters surveys with optical follow up

The shape of the red envelope:i.e. relative ages of galaxies, i.e. H(z)

Highly volatilemutual funds

BondsCD’s

MEASURING DARK ENERGY: future prospects

CMB angular-size distance (improvement?)

Combined with acoustic BAO in galaxy distributionAt 0<z<2 (or so…)

SZ +WL masses

X-rays

SupernovaeKSZ

Gamma-Ray bursts

Not

to

scal

e

ISW

…….

See eg. Jimenez et al 03,

Simon et al 05

Conclusions:

Precision cosmology is here

Cosmology and particle physics are now asking the same questions (but addressing them in complementary ways)

We can test fundamental physics by looking up at the sky

Inflationary models can be ruled in/out (watch this space)

Dark energy: for now it is consistent with a cosmological constant Rolling scalar field/constant/modification of gravity?Cosmological observations have discriminative power.

The next few years (days) will be exciting

Something funny?

SOMETHING FUNNY?

Cornish et al. 2003

Phillips & Kogut 2004

Luminet et al. 2003

Roukema et al. 2004

l

Cl

de Olivera Costa et al. 2004

The football shaped Universe?

Dore talk. etc.

r Tensor to scalar ratio

Up to now scalar

Primordial gravity waves would give tensor modes (perturbations on the metric of space-time alone)

(metric perturbations can be scalar,vector, tensors)

Would be the “smoking gun” of inflation

Would affect CMB Temperature and Polarization

We have not measured it (only weak constraints).

nt exist also, but inflation gives consistency relation

Relation to inflation

Vηε 261 +−=−n

Not only:

But also

ε16=r

2

4 ''''

V

VVM Pl=ξ

ξη 232

3

ln2 −−= rr

kd

dn

“Jerk”

8/2 rnt −=−= ε

Low quadrupole….

ISW

•

φ

Cross-correlate CMB with LSS in the foreground !

Boughn & Crittenden (2003)

Nolta et al. (2003)(X-ray, Radio galaxies)

Scranton et al. (2003) (SDSS)

}

Afshordi et al. (2003) (2MASS)

Gaztanaga et al. (2003) (APM)

Hernandez-Monteagudo et al 2005 (point sources…)

The low multipole anomalies: planarity and alignment

l=2

l=3

Slide from J.Magueijo

Found by many groups in independent ways Found by many groups in independent ways (de Oliveira-Costa et al, 2004; Schwarz et al 2004; Ralston et al 2004; Roukema et al 2005,(de Oliveira-Costa et al, 2004; Schwarz et al 2004; Ralston et al 2004; Roukema et al 2005, Bielewicz et al 2005, etc) Bielewicz et al 2005, etc)

Isotropy?

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Jaffe et al 2005

Eriksen et al 03 also reported N/S asymmetry

Bianchi VIIh

What have we learned?

Glass is half full: Cosmic concordance

Content, geometry, neutrinos, dark energy, P(k) shape, what seeded the primordial perturbations?

Glass is half empty: the puzzles (more space in the discussion)

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In 2000

Kinney Melchiorri Riotto 2000