New CMB (and other) Tests of Inflation, Dark Energy, and other novel physics

1. New CMB (and other) Tests of Inflation, Dark Energy, and other novel physics Marc Kamionkowski (Caltech) Johns Hopkins, 23 May 2010

2. What you’re about to hear • Review of standard inflationary scenario • Where we are now • The current paths forward • Some new CMB tests of inflation (statistical isotropy) • An explanation for a possible anomaly • Quintessence and cosmological birefringence

3. Isotropy problem: Why is the Universe so smooth?

4. I. Inflation:

5. The mechanism: Vacuum energyassociated with new ultra-high-energyphysics (e.g.,grand unification, strings,supersymmetry, extra dimensions….)

6. Inflation prediction #1: The Universe is flat

7. The Geometry of the Universe Warped spacetime acts as lens: “flat” “open” “closed” (MK, Spergel, Sugiyama 1994)

8. Map of CMB (Boomerang 2000) Sizes of hot/cold spotsUniverse is flat

9. More quantitatively Fourier amplitude wavenumber l~1/θ

10. Inflation prediction #2: Primordialdensity perturbations

11. Inflation predicts matter power spectrum • with i.e.,

12. ns<1 P(k) ns=1 ns>1 k

13. WMAP:

14. WHAT NEXT???

15. STRUCTURE FORMATION GEOMETRY SMOOTHNESS INFLATION What is Einfl? STOCHASTIC GRAVITATIONAL WAVE BACKGROUND with amplitudeEinfl2

16. 10-38 sec opaque transparent Transparent to gravitational waves

17. Detection of gravitational waves with CMB polarization “E modes” “B modes” Temperature map: Polarization Map: Density perturbations have no handedness” so they cannot produce a polarization with a curl Gravitational waves do have a handedness, so they can (and do) produce a curl (MK, Kosowsky, Stebbins 1996; Seljak, Zaldarriaga 1996)

19. And one final prediction: Gaussianity • Gravitational potential (e.g., Verde, Wang,Heavens, MK, 2000) with fNL<1 (e.g., Wang & MK, 2000) Forecast that fNL as small as ~5 detectable by forthcoming Planck satellite Gaussian field

20. Not gaussian Current constraints (WMAP5,SDSS (Slosar,Hirata et al.)): |fnl|<100 Gaussian T/T

21. Inflation doing very well • Location of first acoustic peak; flat Universe • Nearly scale-invariant spectrum • Adiabatic perturbations • Consistent with Gaussian

22. Next steps • Test whether ns differs from 1 • Seek inflationary gravitational-wave background with CMB polarization either from space, ground, or balloon (cf., Jaffe, MK, Wang 2000; SPIDER, Keck Array, CLASS, PIPER, Planck, CMBPol) • Seek gravitational waves directly with BBO/DECIGO (e.g., Smith, Cooray, MK, 2006,2008) • Search for non-Gaussianity

23. II. But is there more? (Pullen,MK, 2007) • Inflation predicts Universe statistically isotropic and homogeneous • Statistical isotropy: Power spectrum does not depend on direction; i.e., • Statistical homogeneity: Power spectrum does not depend on position: • These are predictions that can be tested!!

24. To test…. • Require family of models that violate statistical isotropy and/or homogeneity, with departure from SI/SH parametrized by quantity that can be dialed to zero • Develop estimators that measure SI/SH-violating parameters from observables

25. Statistical isotropy • Consider models withand • Most generally,with L=2,4,6,… (Note: cannot get dipole from SI violation!!)

26. Example: An inflationary model(Ackerman, Carroll, Wise, 2007) • Spontaneous breaking of Lorentz symmetry during inflation produces nonzero vector field; imprints quadrupole dependence of power on direction: • Then, temperature fluctuations,

27. Statisticallyisotropic Apowerquadrupole

28. How to measure gLM Lots of equations…..e.g.,

29. Smallest detectable quadrupole anisotropy

30. Can also look with galaxy surveys (Ando,MK, PRL 2008) • Probe on distance scales ~10-100 Mpc, where δ~1, and evolution of density perturbations becomes nonlinear • Anisotropy in primordial power may get altered • Have shown that amplitude of primordial power quadrupole suppressed, but by <7%, in quasilinear regime • Pullen-Hirata have now found (with SDSS) strong constraints to power quadrupole

31. Other weird inflation: bumps in the inflaton potential (Pahud, MK, Liddle 2008) • Suppose inflaton potential: WMAP:

32. IV. Hemispherical Power Asymmetry from Inflation(Erickcek, MK, Carroll, 2008; Erickek, Carroll, MK, 2008; Erickcek, Hirata, MK, 2009) Eriksen et al. found >3σ evidence forpower asymmetry in WMAP1 and WMAP3

33. Isotropic power

34. A power dipole

35. Recall: Violation of statistical isotropy cannot produce power dipole. • Must therefore be violation of statistical homogeneity • …..need spatial modulation of power….

36. Can it be due to a large-scale inflaton mode? • P(k) ~ V3/2/V’, with V(ϕ) evaluated at valuewhen k exited horizon during inflation • If there is a large-scale fluctuation in ϕ, then may get variation in P(k) across Universe

37. Problem: • If ϕ varies, then V(ϕ) varies large-scale density fluctuation, which is constrained to be very small by CMB quadrupole/octupole(Erickcek, MK, Carroll, arXiv:0806.0377; Erickcek, Carroll, MK, arXiv:0808.1570) • Real problem: One scalar field (inflaton) controls density perturbations (which we want to vary across Universe) and the total density (which cannot vary)

38. Solution • Add second scalar field (curvaton); energy density generated by one and perturbations generated by other (or both by some combination) Curvaton Inflaton

39. Explaining the power asymmetry • Postulate long-wavelength curvaton fluctuation Δσ • Keep inflaton smooth This is now the curvaton!

40. Model parameters • R: fraction of total energy density from curvaton decay • ξ : fraction of total power P(k) due to curvaton • Amplitude Δσ and wavelength of long-wavelength fluctuation fixed by amplitude A of power asymmetry • R-ξ parameter space constrained by CMB quadrupole/octupole constraint to homogeneity

41. Model prediction: non-Gaussianity • Mapping from curvaton to density perturbation nonlinear • Predicts non-Gaussianity, with fnl = 5 ξ2 / (4R) • Current constraint fnl < 100 constrains R-ξ parameter space • Asymmetry A requires some nonzero fnl

42. 50<fnl<100 Upper limitfrom CMBhomogeneityconstraint Lower limitfrom fnl<100 12<fnl<100

43. More recent development! • SDSS quasar distribution/clustering restricts asymmetry to be small on smaller distance scales (Hirata 2009)

46. Concordance of small-scale SI with CMB anomaly possible (but just barely), but not easy: Requires isocurvature mode from curvaton decay (Erickcek, Hirata, MK 2009)

47. III.Cosmological Birefringence(Lue, Wang, MK 1999; MK 2008; Gluscevic, MK, Cooray, 2009; MK 2010) • Is physics responsible for inflation or cosmic acceleration also parity violating? • Polarization E and B modes have opposite parity; EB correlation therefore signature of parity violation

49. Rotation of CMB Polarization • E.g., suppose quintessence field Φ(t) couples to electromagnetism through: Time evolution of Φ(t) leads to rotation, by angle α, of CMB polarization as photons propagate from CMB surface of last scatter (Carroll, Field, Jackiw 1998) Rotation induces EB cross-correlation with same shape as original EE power spectrum (Lue, Wang, MK 1999) WMAP/BOOMERanG/QUaD searches: α<few degrees (Fenget al., astro-ph/0601095; Komatsu et al. 2008; Wu et al. 2008)