licia verde university of pennsylvania lverde connecting cosmology to fundamental physics
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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:
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
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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2 10 100 1000
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
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
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)
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
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
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?
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)