Download - Opening Thoughts
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Opening Thoughts
Wendy FreedmanCarnegie Observatories, Pasadena
CAChicago, September 2002
COSMO-02
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Dear Wendy and David:Cosmo-02 has proven even more popular than we
had anticipated… Your two presentations constitute the opening and closing of the conference,… we are asking you for a combination of judgment, advice, inspiration and prognostication for its practictioners.
Goals set by our friendly Organizing Committee…
And I’ll tell you what the dark energy is…
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Dear Wendy and David:Cosmo-02 has proven even more popular than we had
anticipated… Your two presentations constitute the opening and closing of the conference,… we are asking you for a combination of judgment, advice, inspiration and prognostication for its practictioners.
(In particular we are *not* looking for an overview or summary – give us your personal point of view.) The talks are short (25 minutes…) and we realize that we are asking you to do the nearly impossible.
We trust that all of our speakers will make an extra effort to come as close as possible to the unrealistic goals we have set for them.
Sincerely,
Goals set by our friendly Organizing Committee…
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Successes:• Inflation, gravitational instability plus cold dark matter…
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Power Spectrum
~ mh ~ 0.25 § 0.05
Primordial power spectrum: P(k) / kn (n=1 scale invariant)
2dFGRS
Tegmark (2002)
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CMB Anisotropies
1 2
1/ 22
( , )lm lm
lm l
T T a Y
a C
1 1 1 2 2 2( , ) ( , )T T
1.03 § 0.03
flat geometryT0 = 2.725 § 0.001K
n = 1.05 § 0.06
Dasi, Boomerang, MAXIMA, CBI
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Troubles: Inflation + Cold Dark Matter
1. poor fit to galaxy power spectrum for Einstein-de Sitter model (SCDM: m = 1, = 0, h = 0.5)2. predicts excess of small satellites3. predicts central cusps in density profiles
Moore et al. 1999
Moore et al.
2. Numbers of satellites 3. Cuspiness of profiles
} on small scales
model
data
SCDM CDM
OCDMCDM
Jenkins et al. (1997)
1. Power spectrum
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Neils Bohr
“How wonderful that we have met with a paradox. Now we have some hope of making progress.”
-Neils Bohr
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Taking Stock of Where We Are
• CDM simulations fail to fit distribution of galaxies on large scales• no evidence for m = 1• age discrepancy
Open universe fails because:
Einstein-de Sitter model fails because:
• CMB anisotropies yield 0 = 1
Variants to CDM: Hot dark matter fails because:• free streaming wipes out seeds for structure formation
Galaxy kinematics X-ray gas Lensing
Cluster baryons m ~ 0.3
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Taking Stock of Where We Are
Lambda CDM universe current winner because:
• excellent fit to galaxy power spectrum on large scales• consistent with faint supernovae at high redshifts• resolves age discrepancy• consistent with LSS+CMB anisotropy results• no single point failure
… and no better alternatives!
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Inflation + Cold Dark Matter+ Dark Energy
2Df Power Spectrum + CDM
from Percival et al. 2001
CMB
Supernovae
H0 KeyProject
m = 0.3 = 0.7 h = 0.7
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Critical Missing Pieces to the Current “Standard
Model”• Cold dark matter dominates the matter density
and is in an unknown form• The overall mass-energy density is dominated by
dark energy, for which there is currently no explanation
• The dynamics of inflation depends on particle physics at high energy, and nothing is known of the hypothetical scalar field that drives inflation
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The Challenge:
1. Why the small value?
2. Why now?
Observed: · 10-30 g cm-3
Quantum field theory: = 1Quantum gravity: · 10+90 g cm-3
Supersymmetry: · 10+30 g cm-3
Planck
EW
BBN
NOW
log(a)
Carroll (2001)
“The mystery of thecosmological constant is probably the most pressing obstacle to significantly improving the models of elementary particle physics derived from string theory.” Witten (2000)
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: Blunder, Convenient, or Correct?
1900 1920 1940 1960 1980 2000
Year
SN1a CMB
Freedman (2000)
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2
2
2
8 expansion rate
3
4 13 deceleration parameter
3
a k G aH
a a a
a G ap q
a a H
= b + CDM + + rad + X +…0 ´ / crit
crit = 3H02/8G
Cosmological Framework
Essential to determine equation of state fordark energy:
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2
2
2
8 expansion rate
3
4 13 deceleration parameter
3
a k G aH
a a a
a G ap q
a a H
Essential to determine equation of state for dark energy :
= b + CDM + + rad + x +…0 ´ / crit
crit = 3H02/8G
Cosmological Framework
w = P(z) / z)
z) / (1 + z)3(1+w)Matter: m / (1+z)3 w = 0Radiation: r / (1+z)4 w = 1/3Vacuum: / (1+z)0 w = -1
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16 Cosmological Parameters
• first set: 10 parameters describing FLRW model -- the expansion -- global geometry -- age -- composition H0, q0, w, t0, T0, 0, b, CDM, , x
2 sets of parameters:
• second set: 6 parameters describing the deviations from exact homogeneity S, T, 8 , n, nT , dn/d ln k
Freedman & Turner (Science, 2002)
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Table of Cosmological Parameters
Part I: 9 global FLRW parameters:
Freedman & Turner (Science, 2002)
H0 72§7km/sec/Mpc Present expansion rate
q0 -0.67 § 0.25 Deceleration parameter
t0 13 § 1.5 Age of the Universe
T0 2.725 § 0.001K CMB temperature
0 1.03 § 0.03 Density parameter
b 0.039 § 0.008 Baryons
CDM 0.3 § 0.05 CDM
0.002 – 0.05 Massive neutrinos
X 0.7 § 0.1 Dark energy
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Table of Cosmological Parameters
Part II: 6 fluctuation parameters:
Freedman & Turner (Science, 2002)
S 10-10 Scalar amplitude
T < S Tensor amplitude
8 0.9 § 0.1 Mass fluctuations (8 Mpc)
n 1.05 § 0.09 Scalar index
nT ------ Tensor index
dn/d ln k -0.02 § 0.04 Running of scalar index
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CMB Anisotropies• Robust measure of 0 • But large degeneracies
H0=70
Lineweaver (2001)
• Can have same geometry, but very different matter content
•To break degeneracies: H0, SNIa, galaxy power spectrum, weak lensing
• CMB measurements give no information on w(z)
m and are not measured
independently from the CMB alone.
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expected precision
-1 -101 0 50 km s Mpc
0.9 0.1CDM B
n r H
MAP
Angular power spectrum
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Constraining Quintessence
Solid line: wq = -0.8Dashed line: w = -1
A Challenge!!!
Best fit: wq = -0.8 q = 0.72
Baccigalupi et al. 2001
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Prognostication***
*** Beware of observers willing to tell
the future….
Einstein will turn out to be right about the cosmological constant
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Prognostication***
*** Beware of observers willing to tell
the future….
Einstein will turn out to be right about the cosmological constant
Either way!…
R–1/2Rg= 8GT+ g“My biggest blunder”
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Looking Ahead
CERN
CDMS in the Soudan mine
COBE
Predicted Planck
LISA orbit
SNAP
Fermilab
Planck
OWL – 100m telescope
CMB Polarization
Direct expansion rate: 2 m/s/century!
LHC prototype beam collider
CyclicBranes ???
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Magellans I and II domes
The Magellan Telescopes
CarnegieHarvardMITArizonaMichigan
Las Campanas, Chile
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•UBVRIJHK observations
•3 telescopes, coordinated
followup, 5 years
Carnegie/Las Campanas Infrared SN
Survey
>300 6.5m Magellannights (2003-2008)
•Infrared Hubble diagram •Decline-rate relation
• H-band may be insensitive to decline rate
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Carnegie Centennial Lectures
Carnegie Centennial Symposium
Measuring and Modeling the Universe
http://www.ociw.edu/ociw/symposia/symposium2
November 18-22, 2002
Pasadena, CA
Malcolm Longair John SchwarzLisa Randall Michael TurnerAlan Guth Steven WeinbergMarc Kamionkowski Wendy FreedmanJohn Carlstrom Chris KochanekJohn Tonry Joe SilkDavid Spergel Andrew LangeMatias Zaldiarraga Tony ReadheadLyman Page Sandy FaberRoger Blandford Alex Filippenko
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Are We Living in a Golden Age?
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Are We Living in a Golden Age?
Or are we still living in a Bronze Age?…
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Are We Living in a Golden Age?
Or are we still living in a Bronze Age?…
Or taken to epicycles?…
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Are We Living in a Golden Age?
Or are we still living in a Bronze Age?…
Let us look forward to an Age of Reason and understanding!…
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