cosmic microwave background radiation: z=1000 - z= 10
DESCRIPTION
Cosmic Microwave Background Radiation: z=1000 - z= 10. David Spergel Princeton University. Standard Cosmological Model. General Relativity + Uniform Universe Big Bang Density of universe determines its fate + shape Universe is flat (total density = critical density) Atoms 4% - PowerPoint PPT PresentationTRANSCRIPT
Cosmic Microwave Cosmic Microwave Background Radiation:Background Radiation:
z=1000 - z= 10z=1000 - z= 10
David SpergelDavid Spergel
Princeton UniversityPrinceton University
Standard Cosmological ModelStandard Cosmological Model
General Relativity + Uniform Universe Big BangGeneral Relativity + Uniform Universe Big Bang Density of universe determines its fate + shapeDensity of universe determines its fate + shape
Universe is flat (total density = critical density)Universe is flat (total density = critical density) Atoms 4%Atoms 4% Dark Matter 23%Dark Matter 23% Dark Energy (cosmological constant?) 72%Dark Energy (cosmological constant?) 72%
Universe has tiny ripplesUniverse has tiny ripples Adiabatic, scale invariant, Gaussian FluctuationsAdiabatic, scale invariant, Gaussian Fluctuations Harrison-Zeldovich-PeeblesHarrison-Zeldovich-Peebles Inflationary modelsInflationary models
Quick History of the UniverseQuick History of the Universe
Universe starts out hot, Universe starts out hot, dense and filled with dense and filled with radiationradiation
As the universe expands, As the universe expands, it cools. it cools.
• During the first minutes, light During the first minutes, light elements formelements form
• After 500,000 years, atoms formAfter 500,000 years, atoms form• After 100,000,000 years, stars start After 100,000,000 years, stars start
to formto form• After 1 Billion years, galaxies and After 1 Billion years, galaxies and
quasarsquasars
Thermal History of UniverseThermal History of Universe
z
104 103
radiation
matterNEUTRAL
IONIZED
Growth of FluctuationsGrowth of Fluctuations
•Linear theory
•Basic elements have been understood for 30 years (Peebles, Sunyaev & Zeldovich)
•Numerical codes agree at better than 0.1% (Seljak et al. 2003)
Best fit model
cosmic variance
Temperature
Temperature-polarization
1 deg
85% of sky
CBI ResultsCBI Results
ACBAR, VSA also tests physics of damping tailACBAR, VSA also tests physics of damping tail Important confirmation of theoryImportant confirmation of theory Improves parameter constraintsImproves parameter constraints
Readhead et al. (2004)Readhead et al. (2004)
Astro-ph/0409569Astro-ph/0409569
Structure FormationStructure Formation
Model Predicts Universe Model Predicts Universe TodayToday
SDSS Tegmark et al.
Astro-ph/0310723
Verde et al. (2003)
Consistent ParametersConsistent Parameters
WMAP+CBI+WMAP+CBI+ACBARACBAR
All CMB(Bond)All CMB(Bond) CMB+CMB+
2dFGRS2dFGRS
CMB+SDSS CMB+SDSS (Tegmark)(Tegmark)
bbhh22 .023 .023 + .001 .0230 .0230 + .0011 .023 .023 + .001 .0232 .0232 + .0010
xxhh22 .117 .117 + .011 .117 .117 + .010 .121 .121 + .009 .122 .122 + .009
hh .73 .73 + .05 .72 .72 + .05 .73 .73 + .03 .70 .70 + .03
nnss.97 .97 + .03 .967 .967 + .029 .97 .97 + .03 .977 .977 + .03
.83 .83 + .08 .85 .85 + .06 .84.84 + .06 .92 .92 + .08
Zentner & Bullock 2003
Top Hat CollapseTop Hat Collapse
Focus on overdensityFocus on overdensity Follow evolution of Follow evolution of
isolated sphereisolated sphere ExpansionExpansion Turn-aroundTurn-around VirializationVirialization
Press-Schechter FormalismPress-Schechter Formalism
Probability of being in Probability of being in an overdense regionan overdense region
Halo Mass FunctionHalo Mass Function
Do Stars Form in the Halos?Do Stars Form in the Halos?
•Can the gas cool?
•Metals usually dominate the cooling --- but there are no metals
•Molecular hydrogen is the only significant cooling in primordial gas
•Molecular hydrogen usually forms on dust…but there is no dust
•Formation through H+
Numerical SimulationNumerical Simulation
CDM initial conditionsCDM initial conditions HydrodynamicsHydrodynamics Gas chemistryGas chemistry Radiative TransferRadiative Transfer Simulations usually Simulations usually
show the formation of show the formation of a single massive stara single massive star100 - 1000 solar masses100 - 1000 solar masses
No fragmentation seenNo fragmentation seenAbel 2003
First StarsFirst Stars
Massive stars with no primordial metalsMassive stars with no primordial metals Very hot surface--- lots of ionizing photonsVery hot surface--- lots of ionizing photons
• Destroys H2 -- suppresses star formationDestroys H2 -- suppresses star formation Short-livedShort-lived
• Supernova explosions?Supernova explosions? Shocks compress gasShocks compress gas Shocks accelerate cosmic rays-- Compton cool and Shocks accelerate cosmic rays-- Compton cool and
produce X-rays. X-rays ionize universe and produce H2produce X-rays. X-rays ionize universe and produce H2
• Gamma-ray bursts?Gamma-ray bursts?• Enrich environment with metalsEnrich environment with metals
Can We Observe the First Can We Observe the First Stars?Stars?
Direct detection of high z objectsDirect detection of high z objects GalaxiesGalaxies Gamma Ray BurstsGamma Ray Bursts QuasarQuasar
RemnantsRemnants Low z starsLow z stars Chemical ContaminationChemical Contamination
ReionizationReionization
Effects of Reionization on Effects of Reionization on CMBCMB
Temperature Power SpectrumTemperature Power Spectrum Suppression of fluctuations at l > 40Suppression of fluctuations at l > 40 Generation of new fluctuations at l > 10Generation of new fluctuations at l > 10 Generation of small scale fluctuationsGeneration of small scale fluctuations
PolarizationPolarization Generates large scale temperature Generates large scale temperature
polarization correlationpolarization correlation Generates large scale polarization-Generates large scale polarization-
polarization correlationpolarization correlation
Reionization andReionization andTemperature SpectrumTemperature Spectrum
Suppression of small Suppression of small scale fluctuationsscale fluctuations
Additional fluctuations Additional fluctuations generated on large scalesgenerated on large scales
Degenerate with Degenerate with variations in slopevariations in slope
Suppression exp(-2)
CMB PolarizationCMB Polarization
CMB polarization can CMB polarization can be split into two be split into two pieces: E and Bpieces: E and B
Scattering converts Scattering converts local temperature local temperature quadrupole into E quadrupole into E signalsignal
Generates TE and EE Generates TE and EE signalsignal
EE Polarization SignalEE Polarization Signal
Amplitude and peak Amplitude and peak position sensitive to position sensitive to reionization historyreionization history
Holder & Hu 2003
Doppler Effect ContributionDoppler Effect Contribution
•Vanishes to linear order (except at the largest scales)
•Doesn’t vanish to 2nd order (Ostriker-Vishniac effect)
•Inhomogeneous reionization leads to additional fluctuations
Why Is Polarization Difficult to Why Is Polarization Difficult to Observe?Observe?
Weak signalWeak signal signal is statistical rather than a detection in signal is statistical rather than a detection in
each pixeleach pixel ForegroundsForegrounds
Synchrotron (dominant)Synchrotron (dominant) DustDust
Systematic UncertaintiesSystematic Uncertainties
WMAP ResultsWMAP Results
Significant uncertainty in Significant uncertainty in reionization redshiftreionization redshift
Will improve with more data Will improve with more data Polarization auto-correlationPolarization auto-correlation ~0.1 in 4 year data~0.1 in 4 year data
Current Estimate of Optical Current Estimate of Optical DepthDepth
Significant uncertaintySignificant uncertainty Temperature data pushes fit towards low tauTemperature data pushes fit towards low tau Polarization data pushes fit towards high tauPolarization data pushes fit towards high tau
ACT:The Next ACT:The Next StepStep
Atacama Cosmology Atacama Cosmology TelescopeTelescope
Funded by NSFFunded by NSF Will measure CMB Will measure CMB
fluctuations on small fluctuations on small angular scalesangular scales
Probe the primordial Probe the primordial power spectrum and the power spectrum and the growth of structuregrowth of structure
ACT COLLABORATIONSACT COLLABORATIONS
SchoolsGovernment Labs Museums
…united through research, education and public outreach.
PENN
Haverford
Princeton
CUNYTorontoCatÓlica
Simulations of mm-wave data.
1.40<1%
≈2%Survey area
High quality area
150 GHz SZ Simulation MBAC on ACT 1.7’ beam2X noise
PLANCK
MAP
PLANCK
Where will we Where will we be with CMBbe with CMB
Bond et al.
astro-ph/046195
Cosmic Timeline for ACT ScienceCosmic Timeline for ACT Science
z = 1000t = 4 x 104 yrs
z = 7t = 3 x 106 yrs
z = 1t = 1 x 109 yrs
z = .25t = 12 x 109 yrs
now
• First galaxies • Universe is reionized• Ostriker-Vishniac/KSZ
• Surveys of Sunyaev-Zel’dovich (SZ) clusters• Diffuse thermal SZ
• Initial conditions for structure formation
• N(mass,z) – Evolution of Cosmic Structure• Lensing of the CMB• The growth of structure is sensitive to w and mn
• Additional cross-checks from correlations among effects
• Extraction of cosmological parameters
Primary CMB CMB Lensing OV/KSZ Diffuse Thermal SZ Cluster Surveys
Sunyaev-Zel’dovich (SZ) clustersSunyaev-Zel’dovich (SZ) clusters
e-
e-
e-
e-
e-
e-
e-
e-
e-
Coma Cluster Telectron = 108 K
Optical: Redshift and Mass
mm-Wave: SZ –Compton Scattering
X-ray Flux: Mass
SZ SignatureSZ SignatureHot electron gas imposes a unique spectral signature
NO SZ Contribution in Central Band
145 GHzdecrement
220 GHznull
270 GHzincrement
1.4°x 1.4°
Coordinated Cluster Coordinated Cluster MeasurementsMeasurements
Identify and measure >500 clusters in an
unbiased survey with multi-wavelength observations
Galaxy Cluster
HOT Electrons
• Mass limits of 3 x 1014 estimated from simulations• Science derived from N(mass,z)
CMB
-1850
(K)
0
1820
Lensing of the CMBLensing of the CMB
1.4°x 1.4°
• Lensing arises from integrated mass fluctuations along the line of sight.
• The CMB acts as a fixed distance source, removing the degeneracy inherent to other lensing measurements.
• Signal at l = 1000-3000
• Image distortion – only a minor effect in the power spectrum.
• Must have a deep, high fidelity map to detect this effect.
Lensing of the CMBLensing of the CMB-34
(K)
0
34
1.4°x 1.4°
Lensing Signal
• RMS signal well above noise floor.
• Isolate from SZ and point sources spectrally.
• Identify with distinctive 4-point function.
2% of CMB RMS
Cross-Correlating Lensing Cross-Correlating Lensing and CMBand CMB
CMB provides a source plane at z = 1100 with CMB provides a source plane at z = 1100 with very well determined statistical properties (but very well determined statistical properties (but poorer statistics)poorer statistics)
CMB + Quasar & Galaxy Counts will measure CMB + Quasar & Galaxy Counts will measure biasbias
CMB lensing+ Galaxy lensing cross-CMB lensing+ Galaxy lensing cross-correlation improves parameter correlation improves parameter measurements by roughly a factor of 3 measurements by roughly a factor of 3 (Mustapha Ishak)(Mustapha Ishak)
CMB + SN
X-correlate
Add LensingCMB + Lensing
ACT \REGION: Target for ACT \REGION: Target for future lensing surveysfuture lensing surveys
ACT will begin surveying in 2006
We already plan deep multi-band imaging with SALT of low extinction part of ACT strip (200 square degrees)
Would be a very interesting target for a lensing survey
ACT is but one of several next ACT is but one of several next generation CMB experimentsgeneration CMB experiments
APEX (Atacama APEX (Atacama Pathfinder Experiment)Pathfinder Experiment)
UCB/MPIUCB/MPI 1.4mm and 2 mm obs.1.4mm and 2 mm obs. SZ scienceSZ science
SPT (South Pole SPT (South Pole Telescope)Telescope)
8m at South Pole8m at South Pole Chicago group (2008)Chicago group (2008) Large areaLarge area
• Optimized for SZ/clustersOptimized for SZ/clusters
CMB Observations are an important CMB Observations are an important cosmological toolcosmological tool
Large angle observations have helped solidify a Large angle observations have helped solidify a “standard model of cosmology” that fits a host of “standard model of cosmology” that fits a host of astronomical observationsastronomical observations
Small angle observations use this CMB backlight to Small angle observations use this CMB backlight to probe the emergence of structureprobe the emergence of structure
First stars: OV effect, polarizationFirst stars: OV effect, polarization Cluster properties: SZ effectCluster properties: SZ effect Distribution of mass: lensingDistribution of mass: lensing