1. Primordial Neutrinos and Cosmological Perturbation in the Interacting Dark-Energy Model: CMB and LSS Yong-Yeon Keum National Taiwan University SDSS-KSG Winter Workshop February 20-22, 2007 From CMB + SN1a + structure formation

2. Starlight from Galaxies Stuff we are made of!! Light elements from early hot universe Low CMB temperature fluctuations Accelerated expansion of the universe (High redshift SN) Structure formation scenario compatible with observations Rotation of galaxies Speeding galaxies in clusters Gravitational lensing Hot gas in clusters Matter budget of the cosmos Fig:NASA/WMAP science team

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

4. NASA/WMAP science team Total energy density Baryonic matter density Dawn of Precision cosmology !! Dark energy density Good old Cosmology, … New trend !

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

8. Primordial Neutrinos  The connection between cosmological observations and neutrino physics is one of the interesting and hot topic in astro-particle physics.  Neutrino decouple from thermal contact in the early universe at the temperature of order 1 MeV which coincides with the temperature where light element synthesis occurs.  Precision observations of the cosmic microwave background and large scale structure of galaxies can be used to prove neutrino mass with greater precision than current laboratory experiments.

11. Interacting Dark-Energy models o interacting between cold 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 between neutrinos and dark-energy: (Fardon et al. 2004, Zhang et al. 2005, yyk and Ichiki, 2006)

12. 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.

13. 10 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 ?

14. Interacting dark energy model Example At low energy, The condition of minimization of V tot determines the physical neutrino mass. n v m v  Scalar potential in vacuum

15. Mass Varying Neutrino Model Fardon,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:

16.  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

18. Lessons-I:  Wanted neutrinos to probe DE, but actually are DE.   flat scalar potential (log good) choice, m v < few eV.  Neutrino mass scales as m v ~ 1/n v : - lighter in a early universe, heavier now - lighter in clustered region, heavier in FRW region - lighter in supernovae  An example of the inhomogenous matter distributions:

19. Lessons-II Couplings of ordinary matter to such scalars strongly constrained – must be weaker than Planck: 1/M pl

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

21. With exponential type potential

24. 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 !!

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

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

34. Varying Neutrino Mass Mn=0.9 eVMn=0.3 eV With full consideration of Kinetic term V( f )=Vo exp[- lf ]

39. W_eff Mn=0.9 eVMn=0.3 eV

40. Mn=0.9 eV

41. Mn=0.3eV

42. Power-spectrum (LSS) Mn=0.9 eVMn=0.3 eV

43. e Inverse Power law potential

44. Neutrino mass vs z

45. W_eff(z)

46. CMB spectrum

47. Power spectrum with

48. Constraints from Observations

50. WMAP3 data on Ho vs W

51. Conclusions  Neutrinos are the best probe of SM into DE sector  Possible origin for accelerating universe  Motivates consideration of new matter effects to be seen in oscillations: - LSND interpretation (if MinibooNe has a signal) - Matter/air analyses - Solar MaVaN oscillation Effects - Time delay in the gamma ray bursts.

52. Thanks Thanks For For your attention!