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Dark Matter and Dark Energy Adel Awad October 13 2010 Introduction • Why we care about them? Introduction • Why we care about them? Brief review of standard cosmology The Isotropic Universe First detection 1965 at 7.35 cm Penzias & Wilson Nobel Prize 1978 CMB : tiny anisotropies, huge information -200 µK < ΔT < 200 µK First fine-resolution full-sky map (0.2 degrees) WMAP: 2003, 2006, 2008 (Launched June 2001) The Cosmological Principle • Universe highly isotropic – CMBR anisotropy O(10–5) • Unless we occupy the “center of the Universe,” it must also be homogenous • Isotropy and Homogeneity maximally symmetric space – Flat Euclidean space R3 – Closed three-sphere S3 – Open three-hyperbola H3 2 2 2 2 w x y z R 2 2 2 2 2 w x y z R 2 Friedman Equation • Equation that governs expansion of the Universe – k=–1 (closed), k=1 (open), k=0 (flat) – energy density r d(rR3 ) pd(R3 ), p wr 2 R k 8 GN r 2 R R 3 • First law of thermodynamics: 3(1w) r R • For flat Universe: – Matter-dominated Universe – Radiation-dominated Universe – Vacuum-dominated Universe r R 3 , R t 2 / 3 r R 4 , R t 1/ 2 r R 0 , R e Ht Cosmological parameters • Critical density : put k = 0 today R H R • Density parameters : H 02 (cf. measurements!) 8 GN rc rc 3 8 GN 3H 02 ri (t ) r (t ) i (t ) i ,0 i 0 r rc andc today: • Acceleration : for each fluid i : pi = wi ρi 4 GN a 1 3w 2 ( r 3 p) H 0 (t ) a 3 2 Hubble’s law V = H0 D H0 = 71 ± 4 km/s/Mpc (Hubble, 1929) Rem : 1 parsec ~ 3.262 light years ~ 3.1×1013 km Observational evidence for Dark Matter Theoretical Arguments for Dark Matter • Spiral galaxies made of bulge+disk: unstable as a self-gravitating system need a (near) spherical halo • With only baryons as matter, structure starts forming too late: we won’t exist – Matter-radiation equality too late – Baryon density fluctuation doesn’t grow until decoupling Galactic Dark Matter • Observe galaxy rotation curve using Doppler shifts Rotation curves & Dark Matter 2 m*vcirc Gm* M (r ) r r2 Image UV GALEX, A. Gil de Paz, 2006 “Direct proof” : the Bullet Cluster • Optical image of merging clusters (here: 1E 0657-558) • Reconstruct the shear and the convergence (grav. lensing) 200 kpc Clowe et al. ApJL 2006 • Projected density maps (green contours) “Direct proof” : the Bullet Cluster • X-ray image of the same cluster, 1E 0657-558, by Chandra • Green contours : convergence (prop. to the projected density) 200 kpc • White contours : peaks of at 68.3%, 95.5% and 99.7% C.L. Clowe et al. ApJL 2006 Presence of non-luminous gravitating mass ! Matter census in the Universe 1% 7% Stars Gas in virialised structures 7% Warm/hot gas in IGM Baryons Don’t know what Dark Matter is? Ask a Particle Physicist! 85% DARK MATTER Non-baryonic Mirror Matter “Dark Matter” candidates Champs (charged DM) D-matter Cryptons Self-interacting Superweakly interacting Braneworld DM Heavy neutrino NEUTRALINO Messenger States in GMSB “WIMPs”! Branons Chaplygin Gas Split SUSY Primordial Black Holes … L. Roszkowski WIMP : identity file • Full name : Weakly Interacting Massive Particle – Rem : generic name • Interactions : gravitational, weak nuclear (i.e. « weaker than weak » crosssections) • Mass : high enough so as to be cold today • Life time : stable / sufficiently long to have remained until now • Relic density : Boltzmann equation + freeze-out 27 3 1 3 10 cm .s 2 χ h v • Nature? SUSY? KK Extra-dimensions? New Physics! SUSY & LSP… • Supersymmetry? – Extension of the Poincaré algebra: Q |Boson = |Fermion , Q |Fermion = |Boson {Q, Q} P , [H,Q] = 0 – Unification of gauge couplings, mass hierarchy (Higgs) – Keep B & L conservation R-parity, R = (-1)3B+L(-1)2S – SM particles : R = +1 SUSY particles : R = -1 • R-parity conservation ( if ) Lightest Supersymmetric Particle stable! “Natural” candidate for Dark Matter • MSSM + R-parity Neutralino : Extra Universal Dimensions (EUD) • Kaluza-Klein : extra dimensions Compactification of extra dim. at each pt. of 3D space Periodical conditions Momentum quantification • EUD : all fields propagate in the 5th dim. Dark Matter — related experiments: 2010 World Census Boulby Mine Soudan Mine MILAGRO VERITAS Frejus LHC Canfranc Gran Sasso Antares Nestor Nemo Sudbury STACEE Tevatron MAGIC Baikal TIBET, ARGO-YBJ TACTIC PACT GRAPES Neutrino Telescopes Gamma-ray Telescopes (non-ACT) Gamma-ray Telescopes (ACTs) Direct Detection Exps. Colliders Observing Satellites HESS CANGAROO Fermi PAMELA IceCube (South Pole) G. Bertone, Particle DM: what comes next?, Seminar @ Tuebingen U. Observational evidence for Dark Energy Type-IA Supernovae As bright as the host galaxy Type-IA Supernovae • Clear indication for “cosmological constant” • Can in principle be something else with negative pressure • With w=–p/r, r R3(1w) , R t 2 / 3(1w) • Generically called “Dark Energy” Cosmic Concordance • CMBR: flat Universe ~1 • Cluster data etc: matter~0.3 • SNIA: (L–2matter)~0.1 • Good concordance among three Cosmic Pie Age : 13.7 billion years Particle-physics implications Particle Dark Matter • Suppose an elementary particle is the Dark Matter • WIMP (Weakly Interacting Massive Particle) • Stable heavy particle produced in early Universe, left-over from near-complete annihilation • Electroweak scale the correct energy scale! • We may produce Dark Matter in collider experiments. Particle Dark Matter • Stable, TeV-scale particle, electrically neutral, only weakly interacting • No such candidate in the Standard Model • Supersymmetry: (LSP) Lightest Supersymmetric Particle is a superpartner of a gauge boson in most models: “bino” a perfect candidate for WIMP • But there are many other possibilities (technibaryons, gravitino, axino, invisible axion, WIMPZILLAS, etc) Embarrassment with Dark Energy • A naïve estimate of the cosmological constant in Quantum Field Theory: rL~MPl4~10120 times observation • The worst prediction in theoretical physics! • People had argued that there must be some mechanism to set it zero • But now it seems finite??? Conclusions • Mounting evidence that non-baryonic Dark Matter and Dark Energy exist. • Immediately imply physics beyond the SM • Dark Matter likely to be TeV-scale physics • It is one of the main tasks of LHC experiments to search for any Dark Matter candidates.