Yong-Yeon Keum National Taiwan University SDSS-KSG Winter Workshop February 20-22, 2007

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

2. Accelerated expansion of the universe (High redshift SN) • Structure formation scenario compatible with observations Matter budget of the cosmos • Rotation of galaxies • Speeding galaxies in clusters • Gravitational lensing • Hot gas in clusters • Light elements from early hot universe • Low CMB temperature fluctuations • Starlight from Galaxies • Stuff we are made of!! 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. Good old Cosmology, … New trend ! Total energy density Dark energy density Baryonic matter density Dawn of Precision cosmology !! NASA/WMAP science team

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 modelso 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 betweenneutrinos 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. 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 Vtot determines the physical neutrino mass. nv mv Scalar potential in vacuum

15. 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:

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, 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  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/Mpl

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

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

39. W_eff Mn=0.9 eV Mn=0.3 eV

40. Mn=0.9 eV

41. Mn=0.3eV

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

43. Inverse Power law potential e

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