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The Standard Model of Cosmology
Avishai Dekel, HUJI, PANIC08
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North Galactic Hemisphere
Lick Survey 1M galaxies isotropy→homogeneity North Galactic Hemisphere
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Microwave Anisotropy Probe
February 2003, 2004 WMAP Science breakthrough of the year δT/T~10-5 isotropy→homogeneity
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Homogeneity & Isotropy - Robertson-Walker Metric
comoving radius angular area expansion factor
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kinetic potential curvature vacuum
Friedman Equation Homogeneity + Gravity ( ) kinetic potential curvature vacuum Two basic free parameters closed/open decelerate/accelerate
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Solutions of Friedman eq.
matter era, Λ=0 acceleration expansion forever conformal time collapse big bang here & now
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Dark Matter and Dark Energy
vacuum – repulsion? 1 decelerate accelerate m /2 - =0 open closed flat m + =1 bound unbound =0 EdS 1 2 m mass - attraction
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Luminous Matter 3
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Spiral galaxy M74
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Elliptical Galaxy
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שביל החלב בצבעים
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Luminous mass all sources, all wavelengths
With Λ=0, Universe unbound and infinite?
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Dark Matter 4
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Measuring Dark Matter Disk galaxies: rotation curves
Clusters and Elliptical galaxies: virial theorem All scales: gravitational Lensing Clusters: X-ray Clusters: scattering of CMB by gas Large-Scale: cosmic flows Large-Scale: power-spectrum of density fluctuations Cluster abundance at early times
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Dark-Matter Halos in Galaxies
30,0000 ly dark halo v R flat rotation curve v R 3,000light years
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Flat Rotation Curves: Extended Massive Dark-Matter Halos in Disk Galaxies
Milky Way Sofue & Rubin 2001
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dark-matter halo The Cosmic Web of Dark Matter
the millenium cosmological simulation
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Virial Equilibrium in Clusters of Galaxies
M~7x1014 M V~1500 km/s R~1.5 Mpc
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Gravitational Lensing: Dark Matter in Galaxy Clusters
HST
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Gravitational Lensing
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Observed Radial Peculiar Velocities
Mark III
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POTENT: Cosmic Flows Observe radial peculiar velocities:
Potential flow: Smooth the radial velocity field. Integrate from the origin along radial trajectories to obtain the potential at any point in space. Differentiate to obtain the 3-dimensional velocity field. Compute density-fluctuation field by another differentiation:
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Large-Scale Cosmic Flows - POTENT
Great Attractor
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Dark-Matter Density us 200 Mpc Supergalactic Plane
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Mass Density in 3D 3D dark-matter density Great Attractor
Perseus Pisces Great Void
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Matter Density from Void Outflows
Dekel & Rees 1993 ρ=0 δ=-1 high Ωm low Ωm rees/void21.gif
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2dF Pk Measuring m from the 2dF Survey
power spectrum 2dF Pk Measuring m from the 2dF Survey 2D correlation function angular separation redshift anisotropy in z-space
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Total Mass What is the dark matter made of?
exerting gravitational attraction With Λ=0, Universe still unbound and infinite? What is the dark matter made of?
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Baryonic dark matter: planets, black holes, …
Baryonic Mass Baryonic dark matter: planets, black holes, … Big-Bang Nucleosynthesis:
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Big Bang Nucleosynthesis
only 12.5% n left after decaying to p 75% H + 25% He (in mass) At T~109K deuterium becomes stable and nucleosynthesis starts: A minute later p becomes too cold to penetrate the Coulomb barrier by p in d and the process stops. Rate np2 abundances of d and 3He decrease with b b=0.04 0.01 bh2=0.02
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Non-Baryonic Dark-Matter Particles
Neutralinos, photinos, axions, ... all those damn super-symmetric particles you can’t see… that’s what drove me to drink… but now I can see them!
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Dark Matter and Dark Energy
1 accelerate decelerate unbound bound EdS LSS closed open flat 1 2 m
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measure the expected deceleration under gravitational attraction
Dark Energy measure the expected deceleration under gravitational attraction 8
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The Telescope as a Time Machine
young billions of light-years old 2 millions of light-years age of universe (Gyr) 13.69 13.7 looking far → back in time
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Hubble Deep Field
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Supernova: Crab
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Bright Standard Candle: Supernovae Type Ia
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Luminosity-distance to a standard candle
magnitude = -2.5 log (luminosity) +const. Luminosity distance (DL=dLH0) Observe a sample of z-m Determine M and H0 at low z Find Ωm and ΩΛ by best fit at high z
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Today’s expansion rate V=H0R
Deceleration? distance R nearby supernovae רחוק V velocity V היקום מאיץ
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Acceleration! Past expansion rate V=H(t) R R V distance nearby
far away Saul Brian Perlmutter Schmidt velocity V היקום מאיץ
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Acceleration by a cosmological constant
Big Bang here & now time
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Acceleration Vacuum Energy 25
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Dark Matter and Dark Energy
SN 1 accelerate decelerate unbound bound EdS LSS flat closed open 1 2 m
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Curvature 11
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Use a Standard Ruler known intrinsic length flat curved observed angle
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Cosmic Microwave Background
time
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Origin of Cosmic Microwave Background
horizon big-bang t=0 last-scattering surface Thomson scattering trec~380 kyr T~4000K ct0 T~2.7K c(t0-tdec) here & now t0~14 Gyr horizon at trec ~100 comoving Mpc ~1o transparent neutral H ionized p+e- opaque
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Horizon at last scattering ~ 100 comoving Mpc ~ 1˚
Characteristic Scale time here & now z=0 t=13.7 Gyr space past light cone neutral H transparent last scattering z~1090 t=380 kyr ionized opaque horizon z=∞ t=0 big bang singularity Horizon at last scattering ~ 100 comoving Mpc ~ 1˚
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Acoustic Peaks In the early hot ionized universe, photons and baryons are coupled via Thomson scattering off free electrons. Initial fluctuations in density and curvature (quantum, Inflation) drive acoustic waves, showing as temperature fluctuations, with a characteristic scale - the sound horizon cst. At z~1,090, T~4,000K, H recombination, decoupling of photons from baryons. The CMB is a snapshot of the fluctuations at the last scattering surface. Primary acoustic peak at rls ~ ctls ~ 100 co-Mpc or θ~1˚ (~200) – the “standard ruler”. Secondary oscillations at fractional wavelengths.
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Curvature closed flat open
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Curvature closed flat open
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CMB Temperature Maps isotropy T2.725K T/T~10-3 dipole WMAP 2003
COBE WMAP resolution ~10o resolution ~ 10’ T/T~10-5
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WMAP: Wilkinson Microwave Anisotropy Probe
δT/T~ arcmin Charles Bennett
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Angular Power Spectrum
angle =2/
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Curvature 1st peak closed open flat
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Curvature The Universe is nearly flat: Open? Closed?
Surely much larger than our horizon!
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Dark Matter and Dark Energy
SN 1 open closed flat * accelerate decelerate CMB unbound bound EdS LSS 1 2 m 40
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Other Parameters: Baryons, Fluctuations
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CMB Acoustic Oscillations explore all parameters
compression kctls=π curvature velocity max dark matter initial conditions dissipation rarefaction kcstls=2π baryons
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The ΛCDM model is very successful Accurate parameter determination
curvature dark matter initial fluctuations dissipation baryons
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Polarization by scattering off electrons; re-ionization by stars & quasars at z~10
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Cosmic History galaxy formation dark ages big bang
last scattering t=380 kyr reionization t=430 Myr today t=13.7 Gyr
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Baryonic Acoustic Oscillations observed in the galaxy-galaxy correlation function (SDSS, z=0.35)
D(z=0.35) is 10% of way to surface of last-scattering. Currently have a 4% measurement of s.
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The Sloan Digital Sky Survey
Redshifts to 1M galaxies
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Success of the Standard Model: Fluctuation Power Spectrum
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Success of the LCDM Power Spectum
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Standard ΛCDM Model Parameters
2015: Planck (+BAO+SN) Hubble constant H0=67.8 0.9 km s-1 Mpc-1 Total density Ωm+λ = 0.005 Dark energy density ΩΛ=0.692 0.012 Mass density Ωm=0.308 0.012 Baryon density Ωb= Fluctuation spectral index ns=0.968 0.006 Fluctuation amplitude σ8=0.830 0.015 Optical depth =0.066 0.016 Age of universe t0=13.80 0.02 Gyr
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Beyond the Standard Model
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What is the Dark Energy? “ ‘Most embarrassing observation in physics’ – that’s the only quick thing I can say about dark energy that’s also true.” ……………………………………..Edward Witten or - Cosmological constant in GR? - Failure of GR? Quintessence? Novel property of matter? - Why so small? in cosmology Gev … …vs QFT: 108 Gev4 (ElectroWeak) or Gev4 (Planck) - Why becoming dominant now? (Anthropic principle?)
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Generalized Dark Energy
Cosmological constant Energy conservation during expansion Equation of state Generalized eq. of state e.g. Quintessence Friedman eq. and the fluctuation growth-rate eq. probe different parts of the theory and can constrain w(t)
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Equation of State and its Time Variation
Very close to standard GR with a cosmological constant
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Beyond the Standard ΛCDM Model
2015: Planck (+BAO+SN) Total density Ωtot = 1-Ωk = 0.004 Equation of state w = 0.045 Tensor/scaler fluctuations r < 0.11 (95% CL) Running of spectral index dn/dlnk = 0.02 Neutrino mass ∑ mν < 0.23 eV (95% CL) # of light neutrino families Neff=3.15 0.23
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Neutrino Mass and # of Families
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Open Questions - The Big Bang? Inflation? - What is the dark energy?
- What is the dark matter particle? - How do galaxies form from the cosmic web? - How do stars form in galaxies
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Conclusions - Cosmology has a Standard Model: ΛCDM
- The basic parameters are accurately measured ….using multiple techniques - Mysteries: dark matter, dark energy, big-bang, ….inflation - Next step: probe physics beyond the standard ….model - Current effort: galaxy formation
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Age of the oldest globular star clusters
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Age of an old star cluster
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The Age of the Universe
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