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Cosmological Perturbation in Interacting Dark-Energy: CMB and LSS

Yong-Yeon Keum National Taiwan University KPS meeting, Daegu 2006. From CMB + SN1a + structure formation. Cosmological Perturbation in Interacting Dark-Energy: CMB and LSS. What we know so far. From SNIa and CMB radiation observations, Our universe is almost flat, accelerating.

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Cosmological Perturbation in Interacting Dark-Energy: CMB and LSS

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  1. Yong-Yeon Keum National Taiwan University KPS meeting, Daegu 2006 From CMB + SN1a + structure formation Cosmological Perturbationin Interacting Dark-Energy:CMB and LSS

  2. What we know so far From SNIa and CMB radiation observations, • Our universe is almost flat, accelerating. • The dominance of a dark energy component with negative pressure in the present era is responsible for the universe’s accelerated expansion.

  3. Concordance 2002 2000 LSS CMB

  4. Contents of Matter

  5. Candidates of Dark Energy • Cosmological Constant • Dynamical Cosmological constant (Time-dependent; Quintessence ) - quintessence: potential term + canonical kinetic term - K-essence: non-canonical kinetic term - phantom - quintom -Tachyon field • Modified Gravity (Modified friedman eq.)

  6. Classification of Dark-Energy Models • We redefine two parameter space of observables: -1.38<w<-0.82 (2s) w = P/r

  7. Interacting Dark-Energy modelso interacting between dark-matter and dark-energy: (Farrar and Peebles, 2004)o interacting between photon and dark-energy: (Feng et al., 2006; Liu et al., 2006)o interacting betweenneutrinos and dark-energy:(Fardon et al. 2004, yyk and Ichiki, 2006)

  8. Neutrino Model of Dark Energy • Cosmological constant: • What physics is associated with this small energy scale ?? • It is clearly a challenge to understand dynamically how the small energy scale associated with dark-energy(DE) density aries and how it is connected to particle physics.

  9. Questions : • Why does the mass scale of neutrinos so small ? • about 10-3 eV ~ Eo: accidental or not ? • If not, are there any relation between Neutrinos and Dark Energy ?

  10. Interacting dark energy model Example At low energy, The condition of minimization of Vtot determines the physical neutrino mass. nv mv Scalar potential in vacuum

  11. Mass Varying Neutrino ModelFardon,Kaplan,Nelson,Weiner: PRL93, 2004 • Fardon, Nelson and Weiner suggested that tracks the energy density in neutrinos • The energy density in the dark sector has two-components: • The neutrinos and the dark-energy are coupled because it is assumed that dark energy density is a function of the mass of the neutrinos:

  12. Since in the present epoch, neutrinos are non-relativistic (NR), • Assuming dark-energy density is stationary w.r.t. variations in the neutrino mass, • Defining

  13. Lessons: Wanted neutrinos to probe DE, but actually are DE.  flat scalar potential (log good) choice, mv < few eV. Neutrino mass scales as mv ~ 1/nv: - lighter in a early universe, heavier now - lighter in clustered region, heavier in FRW region - lighter in supernovae Couplings of ordinary matter to such scalars strongly constrained – must be weaker than Planck: 1/Mpl

  14. R.D. Peccei; PRD71 (2005)

  15. b The FNW scenario is only consistent, If there is no kinetic contributions (K=0) and the dark-energy is a pure running cosmological constant !!

  16. Cosmological Perturbation in Interacting Dark-Energy Model CMB and Large Scale Structures YYK and K. Ichiki

  17. Background Equations: Perturbation Equations: We consider the linear perturbation in the synchronous Gauge and the linear elements:

  18. Varying Neutrino Mass With full consideration of Kinetic term Mn=0.3 eV Mn=0.1 eV

  19. W_eff Mn=0.3 eV Mn=0.1 eV

  20. Mn=0.3 eV

  21. Mn=0.1 eV

  22. Power-spectrum (LSS) Mn=0.3 eV Mn=0.1 eV

  23. Conclusions Neutrinos are best probe of SM into DE sector Possible origin for dark energy Motivates consideration of new matter effects to be seen in oscillations: - LSND interpretation - Matter/air analyses - Solar MaVaN oscillation Effects - time delay in the gamma ray bursts.

  24. Serious instability problem: In FKNW model, We have the negative speed of sound. After neutrinos become nonrelativistic, the model has a serious microscopic instability. As a result of this instability, the fluid will not be able to drive the acceleration of the Universe any more. At least one neutino is relativistic, and the other one has to be non-relativistic.

  25. When the neutrino masses are not constant, but vary as a function of time and space, CPT violation occurs naturally even in thermal equilibrium. CPTV helps to understand the matter-antimatter asymmetry of the universe -> spontaneous Baryon Asymmetry However, since the laboratory experimental limit on the CPTV in electrons is so stringent that the induced CPTV in neutrino sector will be much below the sensitivity for the current and future experiments.

  26. Thanks For your attention!

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