Testing Dark Energy with Supernovae

1. Testing Dark Energy with Supernovae Marek KowalskiUniversität Bonn, PI Physikalisches Kolloquium Bonn, 23.10.2009 Supernova 1994D

2. Content • Introduction: the accelerating Universe • SNe observations & cosmological parameters • Constraints on selected Dark Energy models

3. Content • Introduction: the accelerating Universe • SNe observations & cosmological parameters • Constraints on selected Dark Energy models

4. Our Cosmological Framework derives from… Observation: The Universe is expanding Principles: Homogeneous, isotropic Theory: General Relativity  Friedman Equation, which governs expansion Matter Density Cosmological Constant/ Dark Energy Curvature

5. Our Cosmological Framework derives from… Observation: The Universe is expanding Principles: Homogeneous, isotropic Theory: General Relativity  Friedman Equation, which governs expansion

6. Our Cosmological Framework derives from… Observation: The Universe is expanding Principles: Homogeneous, isotropic Theory: General Relativity  Friedman Equation, which governs expansion Matter Density

7. Our Cosmological Framework derives from… Observation: The Universe is expanding Principles: Homogeneous, isotropic Theory: General Relativity  Friedman Equation, which governs expansion Matter Density Cosmological Constant/ Dark Energy

8. Our Cosmological Framework derives from… Observation: The Universe is expanding Principles: Homogeneous, isotropic Theory: General Relativity  Friedman Equation, which governs expansion Matter Density Cosmological Constant/ Dark Energy Curvature

9.  M 1998: Discovery of Dark Energy

10. Flat universe L + M = 1.01+/-0.02  • Weak lensing mass census • Large scale structure • Baryon Accoustic Oscillations M= 0.3 M 1998: Discovery of Dark Energy

11. WMAP 2006

12. Cosmic Microwave Background (CMB) & Curvature of the Universe OpenΩk<0 <1° FlatΩk=0 ≈1° Closed Ωk>0 >1° Acustic horizonvstdec

13. Baryon Acoustic Oscillation (BAO) SDSS, Eisenstein et al. (2005)

14. 3

15. Dark Energy 72% 3

16. Vacuum Energy Ground-state of a scalar quantum field: Casimir effect  Energy difference Vacuum energy density: (with cut-off kmax)

17. Vacuum Energy  Cosmological Constant Zeldovich 1968 Vakuum energy: Before: E = 0After: Ax>0 Pressure (p) of Vacuum energy follows from energy conservation: Ax+Axp = 0  p = -   Vacuum energy has all the properties of the Cosmological constant , i.e. it has negative pressure. A x

18. Dark Energy with equation-of-state: p=wr (p = pressure; r = density)  ρ R -3(1+w) Why now? Matter: r R-3 Vakuum Energy: r = constant Fundamental Problems of Vacuum Energy/Cosmological Constant: • Why so small? • Expectation: rL ~ (Mplanck)4 • 120 orders of magnitudes larger then the observed value!

19. Equation of state: w=p/ A few examples: wM= 0 (matter) wR=1/3 (radiation) w= -1 (cosmological constant) wQ> -1 (quintessence) ws= -1/3 (cosmic strings)

20. Content • Introduction: the accelerating Universe • SNe observations&cosmological parameters • Constraints on selected Dark Energy models

21. ` Perlmutter & Schmitt 2003 11

22. Supernova Type Ia • White dwarf in binary system • Mass transfer up to „critical“ Chandrasekhar mass of 1.4 M • Thermonuclear explosion • Explosion of similar energies • Visible in cosmic distances

23. Astronomers think in… Magnitudes: m = -2.5 log(Flux) + constant Filter: B,V,R,I,Z (400-900 nm)

24. „Stretching“ of time scale: Brightness correction: “Standard candles“ • Brightness not the same for all SNe Brighter SNe have wider light curves.

25. Spectra for identification and redshift determination

26. fainter then expected  A bit brighter M normalization SNe Ia Hubble Diagram •  M • 1 0 0.72 0.28 0 1 Supernova Cosmology Project (SCP)Kowalski et al. (2008) fainter

27. New in Bonn… Supernova Factory Collaboration: Lawrence Berkeley National Lab Laboratorie de Physique Nucleaire et de Haute Energies de Paris Institut de Physique Nucleaire de Lyon Centre de Recherche Astronomy de Lyon Yale University Bonn University

28. SNfactory: producing unique nearby SNe data 1. Discover

29. SNfactory: producing unique nearby SNe data 1. Discover 2. Observe SNIFS: Custom spectrograph for nearby SN observations

30. SNfactory: producing unique nearby SNe data 1. Discover 2. Observe 3. Analyses SNIFS: Custom spectrograph for nearby SN observations

31. SuperNova Integral Field Spectrograph (SNIFS) Microlens array to two channel spectrograph 15x15 = 225 spectra Photometric Channel Galaxy + Sky Acquisition, Guiding Extinction monitoring, calibration SN + Galaxy + Sky Sky Pick-off Prism at SN loc 6” x 6” FOV; 0.4”/spaxel 9.4’ x 9.4’ FOV; 0.14”/pix SN 12

32. Spectrophotometry synthetic photometry of SN2005el From Spectra to Lightcurves Slides: Rui Pereira

33. Spectrophotometry synthetic photometry of SN2005el From Spectra to Lightcurves • One spectrum per point / night • Synthesizable in any filter • Lightcurves + spectral features Slides: Rui Pereira

34. The Union SNe Compilation •  M • 1 0 0.72 0.28 0 1 fainter

35. A heterogenous data sample

36. A heterogenous data sample • Study of • mean deviation • ...

37. Test for Tension high-z low-z mean deviation: OK

38.   M Results: Cosmological Parameters Kowalski et al., 2008 Perlmutter et al., 1999 M

39. Results Cosmological Parameters   Kowalski et al., 2008 Perlmutter et al., 1999 Combination of SNe with: BAO (Eisenstein et. al., 2005) CMB (WMAP-5 year data, 2008) For a flat Universe: … and with curvature: M

40. Equation of state: w=p/

41. Content • Introduction: the accelerating Universe • SNe observations&cosmological parameters • Constraints on selected Dark Energy models

42. Many models to explain cosmic acceleration exist … but none without difficulties. Menu of possibilities: • Quantum Vakuum Energy (static) + it exists! - 60-120 orders of magnitude to large 2. Quintessence (dynamic) + Solves „why now“ problem, connects to inflation? - „smallness“ problem persists, small coupling 3. Modification of gravity (hence, no dark energy) + no Dark Energy - Gravitation in solar system well understood

43. Braneworld Cosmology • Large extra dimensions • can solve the hierarchy • problem of particle physics… • (e.g. unification of forces) • Randall & Sundrum • Arkani-Hamed, Dimopoulos, Dvali • …and will weaken Gravity • at large distances (Dvali, Gabadadze, Porrati - DGP) • apparent acceleration

44. Braneworld Cosmology DGP-model versus LCDM Without systematic: 2stat = 16.1 With systematic: 2sys = 4.0 D. Rubin, E. Linder, MK, et al, 2009

45. mn - ln(1+z) Quintessence Example: Growing Neutrinos Scalar field couples to massive neutrinos Once neutrinos become sub-relativistic, one obtains -like behavior. Today: Massive neutrinos and deviation from w =-1 C. Wetterich (2007), L. Amendola et al. (2007),

46. Early dark energy e Quintessence Example: Growing Neutrinos with sys error Lab constraints: mn2 eV Katrin sensitivity: mn 0.2 eV n-oszillations: mn0.05 eV 3s 2s 1s mn<1.2 (h/0.7)2 eV @ 95 CLstat error only mn<2.1 (h/0.7)2 eV @ 95 CL with sys error D.Rubin, E. Linder, MK et al., (2009)

47. SNAP Future projectsfor Dark Energy Projekt z range # SNe Pan-STARRS 0.1-0.5 ~104 DES (2011) 0.2-0.7 ~2x103 LSST (2015) 0.1-0.9 ~106 SNAP (2017) 0.2-3.0 ~3x103 (JDEM/Euclid) • Other important future methods: • Weak lensing • Cluster rates • Baryon acoustic osciallation

48. Conclusion • The observed acceleration of the Universe poses one of the most fundamental problems in physics today. • So far everything looks consistent with cosmological constant. • Detailed measurement of the dynamics can give insights into the acceleration meachanisms.

49. Ende

50. Resonance length acustict horizon Cosmic Microwave Background (CMB) & Curvature of the Universe Power spectrum as a function of angular scale: WMAP Expand the temperature map with spherical harmonics: