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Kati Nikolics

Kati Nikolics

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Kati Nikolics

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  1. The DARK MATTER Mystery Kati Nikolics

  2. Contents • Evidence for the existence of DM • Properties • Possible Candidates - Theoretical Models • Requirements for experimental detection • Trying to find the cosmic needle in a haystack: DEAP K. Nikolics, SMI Seminar, Nov 9 2007

  3. …dark traces in the Universe… F. Zwicky 1933: Velocity dispersion curves of galaxies show a different shape than expected applying the Virial theorem (v  1/r-1) Huge masses of non-luminous, non-absorbing matter in the halo K. Nikolics, SMI Seminar, Nov 9 2007

  4. Wilkinson Microwave Anisotropy Probe (WMAP) Measurements of the cosmic microwave background anisotropies suggest matter that interacts with photons more weakly than the known forces that couple light interactions to baryonic matter Cosmological baryon mass fraction = baryonic matter/non-baryonic DM: K. Nikolics, SMI Seminar, Nov 9 2007

  5. Energy/matter distribution in the universe • Dark matter ≠ dark energy: dark energy increases the rate of expansion of the universe • Only 4% of the content of the universe is luminous matter OR:  For every gram of baryonic matter there are 5.68 grams of non-baryonic dark matter! • From observations of galaxy clusters: DM≈ 0.2-0.3 K. Nikolics, SMI Seminar, Nov 9 2007

  6. Cosmological Significance of DM • Dark matter dominates internal kinematics and motion of galactic systems • Mass of visible matter not enough for closed universe! • Important factor for structure formation in the universe; without DM formation of galaxies is impossible! Density parameter : average density/critical density K. Nikolics, SMI Seminar, Nov 9 2007

  7. Properties of DM • Baryonic (MACHOs = Massive Compact Halo Objects: black holes, etc.) and non-baryonic (WIMPs = Weakly Interacting Massive Particles: „exotic“ particles) • Stable on cosmological time scales • Right relic density Structures in universe expected to evolve in contrast to actual observations (no clustering possible) K. Nikolics, SMI Seminar, Nov 9 2007

  8. Relic density • The relic density is the proportion of dark matter to the critical mass density: (crit is the density that is required for the universe to be flat) • Obtained by solving the relativistic Boltzmann Equation energy and mass of particles produced in Big Bang to account for observed structures in the Universe? Yields a DM particle mass of ~100 GeV - TeV/c² K. Nikolics, SMI Seminar, Nov 9 2007

  9. From measurements of the cosmic microwave background and the spatial distribution of galaxies: • Cold, non-baryonic matter: nbmh² = 0.111±0.006 • Baryonic part: bh² = 0.023±0.001 h = Hubble constant in units of 100km/(s·MPc) K. Nikolics, SMI Seminar, Nov 9 2007