Dark Matter  Evidence for Dark Matter  Dark Matter Candidates  How to search for DM particles?  Recent puzzling observations (PAMELA, ATIC, EGRET) "From neutrinos....". DK&ER, lecture13 1

Dark Matter 1933 r. - Fritz Zwicky, COMA cluster. Rotation velocity of gallaxies around common center of mass too large for them to be in a bound system. Invisible matter, only gravitational interactions coma In – rotation velocity of gallaxies; halo of invisible matter (?) spherical halo of Dark Matter surrounding a gallaxy P. Mijakowski 2

"From neutrinos....". DK&ER, lecture r. analysis of mass distribution in the region of passing through gallaxy clusters (1E ) (*) Gravitational lensing – gravitational potential (images from Hubble Space Telescope, European Southern Observatory VLT, Magellan) / violet X-rays - Chandra X-ray Observatory (NASA) /rose (*) D.Clowe et al Ap. J. 648 L109 1E Mass of gas typically 2x larger than the mass of visible matter in gallaxies Result: concentration of gravitational mass is where gallaxies are Region of X emission: only 10% of the total mass of the system Comparison of both observations makes Dark Matter necessary Dark Matter – Bullet Cluster P. Mijakowski 3

"From neutrinos....". DK&ER, lecture13 Gravitational lensing Einstein's Bullseyes 4 Elliptical galaxies have DM halos as spiral galaxies

"From neutrinos....". DK&ER, lecture13 What do we know about ? Visible matter (stars, gas): Baryons visible or invisible calculated from BB nucleosynthesis Total matter deduced from gravitational potential energy of galaxies etc. Dark matter: Dark energy: „geometria płaska” k=0 5

"From neutrinos....". DK&ER, lecture13 Dark Matter - candidates Known particles –MACHO’s (Massive Astronomical Compact Halo Objects), np. brown dwarfs, neutron stars, black holes –Neutrinos (Hot Dark Matter - HDM) Postulated particles: –Axions –WIMP-s (Weakly Interacting Massive Particles) - slow, massive, neutral particles, weakly interacting with matter (Cold Dark Matter - CDM) < 7% of mass of gallactic halo (exp. EROS) structure formation requires CDM P. Mijakowski 6

"From neutrinos....". DK&ER, lecture13 WIMPs (WIMP – Weakly Interacting Massive Particle) We are looking for particles:  Neutral  With long lifetime (  ~ Universe lifetime)  Massive ( M  ~ 100 GeV)  Weakly interacting  neutralino  (SUSY) – LSP (Lightest Supersymmetric Particle), is stable (conservation of R parity in SUSY) a good WIMP candidate: neutralino(  ) 18 GeV < M  < 7 TeV LEPcosmology Examples of diagrams (neutralino) P. Mijakowski 7

"From neutrinos....". DK&ER, lecture13 Direct Detection T recoil ~ keV detector  + (A,Z) at rest   + (A,Z) recoil we measure energy of recoiling nuclei resulting from elastic scattering of WIMPs Very many experiments are going on, and new projects studied Stay tuned. 8

"From neutrinos....". DK&ER, lecture13 9 Direct detection – current experimental limits Region above lines is excluded with 3  CL DAMA 1.1x10 5 kg·d (7 years, 100 kg NaI) Hidden assumptions: –interaction (spin dependance) –Galactic Halo Model DAMA NaI, 90% CL region CDMS II, (Ge) (34 kg·d) Edelweiss (Ge) XENON (10kg) 2007, 136 kg·d CDMS II, 2007 prediction Zeplin II (Xe) WARP(2.3 l. Ar)

"From neutrinos....". DK&ER, lecture13 Sun  Earth    scatt Γ capture Γ annihilation  detektor Indirect detection - neutrinos In neutrino telescopes no excess of neutrinos from Sun, Earth center, Gallaxy center when compared to the expected background.     Z P. Mijakowski 10

Super-Kamiokande data sample  live days of SK-I  1892 upward through-going muons  muon length > 7m E  >1.6 GeV  effective area: 1200 m 2  angular resolution: 1 deg Simulation of the background of atmospheric neutrinos with:  Bartol fluxes (1996) (event time sampled from data sample)  „Nuance” for neutrino interactions  muon energy loss in rock – Lipari, Stanev  detector simulation  oscillations S. Desai PhD thesis S.Desai et al., PRD D70, (2004) 11"From neutrinos....". DK&ER, lecture13

Upward-muons (from ν interactions) -SK atm. bkg without oscil with oscil. Normalization: total # of MC events = # of data events Angles with respect to direction from: Sun Galactic center Earthc enter  No excess of neutrinos from the studied objects  Upper limits on muon fluxes are calculated  No excess of neutrinos from the studied objects  Upper limits on muon fluxes are calculated 12"From neutrinos....". DK&ER, lecture13

Upward muons flux limits from various experiments From Earth’ s center From Sun From Galactic center SK 13"From neutrinos....". DK&ER, lecture13

Muon flux limits as functions of WIMP masses Wimps of larger mass produce tighter  beams. Cones are calculated containing 90% of muons from WIMPs: Wimps of larger mass produce tighter  beams. Cones are calculated containing 90% of muons from WIMPs: Earth’s center Sun Galactic center S.Desai et al., Phys.Rev. D70 (2004) "From neutrinos....". DK&ER, lecture13

15 SuperK limit for neutralino elastic cross section (spin independent interactions) comparison with direct detection Comparison with direct detection: model dependent, assuming only spin-independent interactions in Earth and Sun Direct and Indirect event rates: Evt. rate in 1 kg Ge detector = Evt. Rate in m 2 of upward muon detector (assuming SI couplings) » Currently: lowest limit in direct detection -> XENON, ~10 -7 pb ( cm 2 ) for a 100 GeV WIMP

"From neutrinos....". DK&ER, lecture13 16 SuperK limit for neutralino elastic cross section (spin dependent) Limit 100 times lower than from direct search experiments DAMA annual modulation due to axial vector couplings ruled out by this result (Kamionkowski et al.) Kamionkowski, Ullio, Vogel JHEP 0107 (2001) 044

Some recent observations which can indicate Dark Matter particles in Universe "From neutrinos....". DK&ER, lecture13 17

Cosmic-ray Antimatter from Dark Matter annihilation A plausible WIMP candidate is a neutralino χ, the lightest SUSY particle Most likely processes: You are here Milky Way Halo Antimatter particles can result from:  secondary interactions of primary cosmic rays  annihilation of WIMPs gravitationally confined in the galactic halo 18"From neutrinos....". DK&ER, lecture13

19 PAMELA PAMELA is mounted on satellite Resurs-DK1, inside a pressurized container launched June 2006 minimum lifetime 3 years data transmitted via Very high-speed Radio Link (VRL) » Search for dark matter annihilation (e + and p-bar spectra) » Search for anti-He (primordial antimatter) » Study composition and spectra of cosmic rays (including light nuclei) » Study solar physics and solar modulation » Study terrestrial magnetosphere and radiation belts scientific objectives: a Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics

PAMELA detector principle M. Pearce M. Pearce "From neutrinos....". DK&ER, lecture13

21 PAMELA results (positrons) compared to other experiments (*) O.Adriani et al. [PAMELA Collaboration], arXiv (Oct 2008) low energy - solar modulation effects –difference comparing to CAPRICE, HEAT, AMS -> previous solar cycle 5-10 GeV compatibility with other meas. above 10 GeV –observed increase best statistics so far: electrons 9430 positrons...in 500 days in GeV

PAMELA results (positrons) compared to secondary production (*) O.Adriani et al. [PAMELA Collaboration], arXiv (Oct 2008) secondary production (Moskalenko  Strong) spectrum shape completely different ???? 22"From neutrinos....". DK&ER, lecture13

ATIC Baloon born experiment for C.R measurement Operated from McMurdo, Antarctica ATIC-1 15 days (2000/2001) ATIC-2 17 days (2002/2003) 36km Advanced Thin Ionization Calorimeter 23"From neutrinos....". DK&ER, lecture13

24"From neutrinos....". DK&ER, lecture13

25 ATIC results ATIC (red points); AMS (green stars); HEAT (open black triangles); BETS (open blue circles), PPB-BETS (blue crosses); emulsion chambers (black open diamonds); solid curve – galactic spectrum (GALPROP); dashed curve - solar modulated electron spectrum; (*) J. Chang, et al. [ATIC Collaboration], Nature, 456, 362 (2008) e+e- flux

Neutralino annihilation fit to PAMELA & ATIC data To normalize ATIC & PAMELA data a very large or dense clump of DM is required -> annihilation rates (per second): D.Hooper. A.Stebbins,K.Zurek, arxiv (Dec 2008) ASSUMPTIONS » WIMPs annihilation only to W + W - » Annihilation in nearby clump (could be a point source like) secondary production (Moskalenko  Strong) 26"From neutrinos....". DK&ER, lecture13

27 DM annihilation to gammas - EGRET EGRET excess in diffuse galactic gamma ray flux GeV neutralino annihilation?

Summary  Dark Matter consistently needed to understand various astrophysical observations  According to current studies it constitutes around 24% of the total energy of the Universe  The searches of Dark Matter candidates are going on in various experiments: –direct searches –indirect searches using neutrinos from WIMP annihilation  Recently some puzzling observations (PAMELA, ATIC, EGRET) - could be due to DM?? "From neutrinos....". DK&ER, lecture13 28