The dark side of the Universe: dark energy and dark matter Harutyun Khachatryan

1. The dark side of the Universe: dark energy and dark matter Harutyun Khachatryan Center for Cosmology and Astrophysics

2. Content of the Universe after Planck

3. Density proportion evolution

4. Lambda chronology 2013 Planck, density content revision

5. Cosmological models Friedmann-Robertson-Walker metric Spatial curvature K=0 flat (Minkowski), K=+1 positive curvature(sphere) K=-1 negative curvature spectral redshift cosmic redshift Continuity equation Evolution equation

6. Friedmann equations

7. Energy-momentum tensor

8. Omega budget

9. Luminosity distance For concordance model for flat universe dark energy 0.69 matter density 0.31 radiation density 10^-4

10. Cosmological constant Λ? Einstein equations 1916 Einstein 1917

11. Dark energy 1998 Hubble diagram

12. 2011 Nobel Prize in Physics

13. Extragalactic Distance ladder

14. Astrophysical parameters L luminosity, total energy emitted by an object per second. m apparent magnitude, observed brightness. M absolute magnitude, calibrated brightness. M=m-5(log10(DL)-1)

15. Standard candles Classical Cepheids Type Ia Supernovae

16. Cepheid light curve

17. Type Ia Supernovae

18. Crab nebula 1054 A.D. supernova remnant

19. SN Ia light curve

20. Hubble’s law Theory: from FRW metric follows V=H(r)r for small distances, z << 1. Observations: Hubble redshift-distance law of galaxies V = H r V- velocity of the galaxy, r- distance to the galaxy, Hubble’s constant H = 69.32 ± 0.80 (km/s)/Mpc (after Planck).

21. Hubble’s or Lemaitre’s law? Hubble 1929 Lemaitre 1927

22. Hubble diagram indicating accelerated expansion Riess et al. 1998

23. Higher redshifts: gamma-ray bursters • z=1-10 and more (arguable) • emits in few seconds as much as the Sun during its lifetime • nature unknown, some empirical relations exit Can they be used for the Hubble diagram?

24. Calibrating GRBs Empirical relations Amati relation lag versus luminosity relation variability versus luminosity relation H. J. M. Cuesta…..H. G. Khachatryan,.. A&A, 2008

26. Vacuum fluctuations Zeldovich 1967

27. Cosmic coincidence

28. Equation of state, w

29. Dark energy summary • Negative pressure, p=-ρ • Ω=0.69 • Equation of state, cosmological constant w=-1 • Various models: vacuum fluctuations, General Relativity extensions (scalar field coupled, Chern-Simons, f(R), etc), quintessence, holography…

30. Slide by A.Taylor, Motivating EUCLID space mission, 2011

31. Dark matter chronology • 1932- Jan Oort, stellar motion in the local galactic neighbourhood • 1933- Fritz Zwicky, motion in clusters of galaxies • 1970- Vera Rubin, galaxy rotation curves

32. Virial theorem Dark matter Coma cluster 2<T>=Vtot Zwicky, F., Helvetica Physica Act 6 (1933)

33. M31 rotation curve V.C. Rubin & W.K. Ford 1970

34. Galaxy rotation curves

35. Gravitational lensing Einstein 1912,1936

36. Bullet cluster 1E 0657-558

37. Bullet cluster X-ray image

38. Modified Newtonian dynamics

39. MOND theory (by Milgrom) MOND acceleration related to the Newtonian acceleration aN at weak acceleration limit of gravity interpolation function

40. Dark matter summary • Ω=0.27 • Particle candidates: axion, WIMPs, neutrino (small part), supersymmetric particles… • Models: cold dark matter, warm dark matter, hot dark matter • MOND

41. Challenge to homogeneity of the Universe? Greatest cosmic structure

42. 73 quasar cluster z=1.27, longest dimension 1240 Mpc, mean length 500 Mpc R. Clowes et al. MN, 2013

43. Conclusions • Modern cosmology passed to the precision • cosmology era. • Dark energy: favored, cosmological constant • w=-1. The nature unknown. • Dark matter: many candidates, none favored. • The nature unknown. • Challenges to the concordance model (CMB • low multipole anomaly, alignments, non- • Gaussianities…).