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Explore the formation of dark matter structures, linear and nonlinear growth of fluctuations, hierarchical clustering, galaxy bimodality, supernova feedback, elliptical galaxy mergers, high-redshift galaxy formation, and more.
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Outline Part II. Structure Formation: Dark Matter 5. Linear growth of fluctuations by gravitational Instability 6. Statistics of fluctuations: initial fluctuations and the cold-dark-matter scenario 7. Nonlinear growth of structure: spherical collapse, virial equilibrium, Zeldovich approximation and the cosmic web, N-body simulations 8. Hierarchical clustering: Press-Schechter halo distribution, EPS merger trees, galaxy/halo biasing, HOD and correlation function 9. Dark-matter halos: universal profile, the cusp/core problem, dynamical friction, tidal effects, halo shape 10. Substructure of dark-matter halos, phase-space density
Outline cont. Part III. Galaxy Formation: Including gas and Stars 11. Angular momentum: tidal-torque theory, halo spin, disk formation, the AM problem 12. Galaxy bimodality: observations, virial shock heating, star formation and quenching mechanisms, downsizing 13. Dwarf galaxies and supernova feedback 14. Formation of elliptical galaxies by mergers: missing dark matter? origin of scaling relations, origin of red sequence and downsizing 15. Galaxy formation at high redshift: cold streams, clumpy disks and compact spheroids 16. Massive black holes in galaxies: AGN feedback 17. Semi-analytic modeling of galaxy formation
Linear Growth of Fluctuations by Gravitational Instavility 2dF WMAP
2dF Galaxy Redshift Survey ¼ M galaxies 2003 CFA Survey 1980
History Early Universe Cosmic Microwave Background Today time
Cosmological Epochs recombination last scattering 380 kyr z~1000 CMB transparent optical opaque: “dark ages” first stars reionization 180 Myr z=8.81.5 galaxy formation: optical transparent → see galaxies today 13.8 Gyr
Gravitational instability small-amplitude fluctuations: gravitatinal instability: galaxy cluster void 0
ימסוקה גראמה - תויצאוטקלפה לודיג
Gravitational Instability: linear, matter-era : equations Fluid Continuity Euler Poisson ) 1 ( ( ) 0 V (2) V ( V ) V P/ρ Φ 2 ) 3 ( 4 G Uniform background : ( ) . r const 2 8 4 a a G a G 3 ) 1 ( 0 r a x v r 3 2 3 a a a a ) 1 ( / 3 H a a H Perturbati ons : ( , ) ( )[ 1 ( , )] ( ) r t t r t V H t r v P p u u st 1 order : 1 etc. ) 1 ( ( ) 0 H r v v 2 ) 2 ( ( ) ( ) v H r v H v v v c s 2 ) 3 ( 4 G P P P kT 2 u ( ideal gas ) P c s m p
r a Comoving coordinate : s x r a r x r a t t a t x r / / w v a a ) 1 ( ( ) 0 w w 2 1 ) 2 ( 2 ( ) w H w w w a c s 2 2 ) 3 ( 4 [ / 3 ( ) 2 ] G H u 1 ( eq. ) 2 / ( eq. ) 1 a t H 2 2 2 2 4 G a c u s gravity pressure a 3 ( , ) ( ) ( ) ( ) x t a t H t t a u a
a H 2 2 2 2 4 G a c 3 ( ) ( ) ( ) a t H t t a u u s a Static background : 0 . 1 . a a const const u 2 2 2 exp[ ( )] 4 i k x t k c G s u pressure gravity / 1 2 / 3 2 2 / 3 2 4 2 k 4 G c T Jeans scale : u s k M J J J m 2 / 1 2 3 G c J s t t ( ) 0 p Ae Be J stable oscilation s J Expanding background , : J 4 2 t / 2 3 1 At Bt 2 / 3 0 k a t 2 3 3 t 3 2 t t . freezout const 0 0 1 k a t 3 2 t
Properties of the linear growing mode: : 2 linear 2 / 3 ( ) 2 ( ) ( ) H H H t t growing mode D(t) δ D D 3 6 . 0 2 ( ) ( 2 ) f H f 2 HD D 1 continuity v Hf 3 H 2 Poisson irrotation al v v v f The Jeans scale in an expanding universe: k i x k H In space : ( ) k t e r ax k 2 2 for each : 2 4 ( ) same Jeans scale k G k c k k s k
Lecture Statistics of Fluctuations: The Cold Dark Matter Scenario
The Initial Fluctuations At Inflation: Gaussian, adiabatic a realization of an ensemble ensembe average ~ volume average ( ) x fluctuation field ( ) x k i x ~ ( ) Fourier x ke Power Spectrum 2| ) n ( ) | ( P k k k k ~ 2 / K K K rms 2 3 3 3 ~ exp[ ( ) ' ] ' ~ i k k x d k d k d k k 0 0 ' k k k k ' 0 k k ( ) ' k k Dirac 2 / 2 3 ( 3 / ) 3 n 2| P d k M | k k k k 0 k δ Pk 3 / 2 1 n M / 1 2 0 n M 3 . n const M k
Scale-Invariant Spectrum (Harrison-Zel’dovich) R t mass MH t Horizon 3 2 a t H t m M time t 2 / 3 t 2 / 3 2 / 3 ( , ) M t M t H ( ) t M H . const H 1 n P k k 2 / 3 M M
Cosmological Scales mass ~ R ct MH t Horizon 3 2 a t m 3 a matter 4 a rad t0 teq time zeq~104
CDM Power Spectrum MH t mass H growth when matter is self- gravitating H H rad mass t time teq CDM 1 k Pk 2 / 3 3 M k CDM HDM HDM free streeming mass k kpeak m h Meq
Formation of Large-Scale Structure Fluctuation growth in the linear regime: rms fluctuation at mass scale M: Typical objects forming at t: ~ 1 / 2 t 6 3 1 a / ) 3 M M n 0 a 2 ( n 2 / 3 / 1 M a * example 6 M a * HDM: top-down CDM: bottom-up / 1 2 / 1 2 2 2 1 1 free streaming 0 0 M M
Micro-Macro Connection Cold Dark Matter Hot Dark Matter