THINGS BIG & SMALL

1. THINGS BIG & SMALL Dhiman Chakraborty (dhiman@fnal.gov)

2. Outline: Part 2 • Up to the grandest: the Universe at large • Big Bang Cosmology: a brief overview • The three tests of BB cosmology • Cosmic Microwave Background (CMB)  Flat Universe • Large Scale Structure (LSS)  Dark matter • Expansion of the Universe: Supernova 1a (SN1a)  Dark E • Recent/current/proposed experimental programs using ground- and space-based telescopes: • CMB: COBE, WMAP, Planck • LSS: HST, SDSS, LSST, Chandra, XMM-Newton, … • SN1a: HZSNT, SCP, SNAP • Summary of planned HEP & cosmology projects • Outlook THINGS BIG AND SMALL

3. Up to the grandest… THINGS BIG AND SMALL

4. Big Bang cosmology • t=0: the beginning of time & space represents an essential singularity with infinite matter-energy density (r) and temperature (T). • An expansion ensues, governed primarily by GTR. • T & r fall as the universe expands. THINGS BIG AND SMALL

5. Epochs & dominant components • ? : <10-43 s; string (?) • Inflation: 10-38 s; vacuum (inflaton driven?) • Quantum fluctuations imprinted on metric, to be seen later as anisotropies in cosmic microwave background. • Baryogenesis: 10-36 s; radiation/matter(?) • WIMP decoupling • Big Bang Nucleosynthesis (BBN): 1 s; radiation • neutrino decoupling. Best tested part, nB/ng only parameter. • Cosmic Microwave Background (CMB): 1012 s; matter • photon decoupling  transition to matter-dominated era. • Present: 51017 s; vacuum • “Dark energy” drives the universe into accelerated expansion. THINGS BIG AND SMALL

6. Evolution of the Universe THINGS BIG AND SMALL

7. Evolution of the Universe THINGS BIG AND SMALL

8. Pillars of the Big Bang theory • Cosmic microwave background • Abundance of the light elements • Evidence of cosmic expansion Observationally, these measurements are completely independent of each other. They must provide even support for the theory to hold water. THINGS BIG AND SMALL

9. Hubble’s law Based on experimental observation (1929): On average, all galaxies are moving away from each other with speed proportional to distance. Corollary: on large scales, the universe is homogeneous and isotropic- it looks the same in all directions and in all parts – there’s no “center” nor “edge”. Metric for a homogeneous & isotropic universe: R(t): scale factor (dimensionless) THINGS BIG AND SMALL

10. The Friedman equation where , • governs the expansion of a uniform gas-filled universe • r =Energy density (matter+radiation+vacuum) • z t(large z small t,“present”  R = R0  z=0). • H0  60 km/s/Megaparsec (1 Mpc  3.26 light-year) : critical density ( k=0, “flat” universe) : Red shift (Doppler effect) THINGS BIG AND SMALL

11. Matter: w=0  • Radiation: w=1/3  • Vacuum: w=-1  The density components In general, : equation of state parameter : density parameter (i=normal matter, neutrino, dark matter, dark energy, …) In a flat universe dominated by: THINGS BIG AND SMALL

12. Geometry of the Universe Current data   = 1 THINGS BIG AND SMALL

13. Structure formation • Jeans instability in self-gravitating systems cause formation of structures. • Needs initial seed density fluctuations. • Density fluctuations grow little in a radiation- or vacuum-dominated universe. • Density fluctuations grow linearly in a matter -dominated universe. • Baryonic matter alone falls far short of explaining the level of structure seen today. THINGS BIG AND SMALL

14. Theoretical arguments for dark matter • Spiral galaxies made of bulge+disk: unstable as a self-gravitating system  need a (nearly) spherical halo. • With only baryons as matter, structure forma-tion starts too late for us to exist at this time • Matter-radiation equality achieved too late, • Baryon density fluct. can’t grow until decoupling, • Need larger electrically neutral component. THINGS BIG AND SMALL

15. Size-evolution of the universe THINGS BIG AND SMALL

16. Observational verification • A “Standard Model” of cosmology emerges from extensive surveys of: • Anisotropy in cosmic microwave background (earliest structures visible, z  3000): CMB • Large-scale structures (e.g. Galaxies, clusters, grav. lensing, z  5, dark matter,): LSS • Type 1a supernova brightness & redshift (std. candles, z  0.5,  dark energy): SN1a Each gives a linear equation in M,   any two of these determine M, ; the 3rd serves as a cross-check. THINGS BIG AND SMALL

17. CMB: Peeking into the universe’s infancy withthe Wilkinson Microwave Anisotropy Probe THINGS BIG AND SMALL

18. WMAP talk about thermal resolution! THINGS BIG AND SMALL

19. WMAP talk about spatial resolution! THINGS BIG AND SMALL

20. LSS: Surveying galaxies & clusters with normal (HST, SDSS) & x-ray (Chandra, XMM-Newton) vision The XMM-Newton x-ray observatory THINGS BIG AND SMALL

21. LSS: Dark matter in galaxy clusters • Galaxies form clusters bound in a gravitational well. • Hydrogen gas in the well gets heated, emits x-ray. • Allows us to determine the baryon fraction of the cluster. THINGS BIG AND SMALL

22. LSS: Chandra discovers "Rivers Of Gravity" that define the cosmic landscape Four independent teams of scientists have detected intergalactic gas with temperatures in the range 300,000 to 5 million degrees Celsius by observing quasars with the Chandra X-ray Observatory. An artist's rendering illustrates how X-rays from a distant quasar dim as they pass through a cloud of the intergalactic gas. By measuring the amount of dimming due to oxygen and other elements in the cloud - see the spectrum of the quasar PKS 2155-304 in the inset - astronomers were able to estimate the temperature, density and mass of the absorbing gas cloud. THINGS BIG AND SMALL

23. LSS: Chandra discovers "Rivers Of Gravity" that define the cosmic landscape THINGS BIG AND SMALL

24. LSS: Surveying galaxies & clusters with normal (HST, SDSS) & x-ray (Chandra, XMM-Newton) vision The sky is not so dark in x-ray: HST (L), Chandra (R) THINGS BIG AND SMALL

25. Sloan Digital Sky Survey (SDSS) THINGS BIG AND SMALL

26. The M78 nebula, a nursery of stars, as seen by SDSS LSS It is extremely important to know how the mass and energy, most of it dark, is distributed throughout the universe. A particle theory that contradicts cosmological observations will not be viable. THINGS BIG AND SMALL

27. LSS & CMB surveys agree THINGS BIG AND SMALL

28. SN1a: measuring the rate of cosmic expansion using high-z supernovae 1a as standard candles • Nuclear chain reaction in stars with M2Msun (more complex - binaries etc.) • As bright as host galaxy • Brightness not const, but related to fall-off rate. • Apparent brightness gives distance. • Red shift (z) gives relative radial velocity. THINGS BIG AND SMALL

29. SN1a: Clear evidence of accelerated expansion • By SCP+HZSNT using HST & ground-based telescopes. • The cosmological constant fits the bill. • Can in principle be something else with –ve p. • Generally called Dark Energy. THINGS BIG AND SMALL

30. Expansion history of the universe THINGS BIG AND SMALL

31. SN1a: Next step: the Joint Dark Energy Mission The proposed Supernova/ Acceleration Probe (SNAP) THINGS BIG AND SMALL

32. The cosmic concordance • CMB: 1 flat universe. • LSS: M  0.3 • SN1a: L-2M  0.1 • Remarkable agreement • Dark Matter: 23% ± 4% • Dark Energy: 73% ± 4% • (Baryons: 4% ± 0.4%, Neutrinos: ~0.5%) • Remarkable precision (~10%) • Remarkable results THINGS BIG AND SMALL

33. Cosmology summary: The current state of knowledge: • The Universe is geometrically flat, • It is expanding with increasing speed, • Dark energy dominates matter, • Dark matter dominates baryonic matter, • Baryonic matter dominates baryonic antimatter. THINGS BIG AND SMALL

34. Outstanding questions: • Dark Matter: What is it? How is it distributed? • Dark Energy: What is it? Why not WL ~ 10120? Why not WL = 0? Does it evolve? • Baryons: Why not WB≈ 0? • Ultra-High-Energy Cosmic Rays: What are they? Where do they come from? … What tools do we need to address these? THINGS BIG AND SMALL

35. Particle dark matter Suppose an elementary particle constitutes DM • WIMP (Weakly Interacting Massive Particle). • Heavy but stable, neutral, produced in early Universe. • Left over from near-complete annihilation. • No such candidate in the SM, must be new physics! • TeV is the right energy scale. • SUSY: the lightest supersymmetric particle (LSP) is a superpartner of a gauge boson in most models: the “bino” is a perfect candidate for a WIMP. • There are other possibilities (axino, gravitino, axion, technibaryons, axion, Kaluza-Klein particles, …) • In any case, we should be able to produce such WIMPs at colliders of the next generation (LHC, ILC). THINGS BIG AND SMALL

36. Neutralino dark matter THINGS BIG AND SMALL

37. The enigma of dark energy • A naïve estimate of the cosmological constant in quantum field theory  rL  MPlanck410120 times the onserved value. • The worst prediction in theoretical physics! • People had argued that there must be some mechanism to set it to zero. • But now it seems finite!!! • Quintessence? • A scalar field slowly rolling down the potential hill. • Will set L to 0 when it reaches the minimum? • Must be extremely light: O(10-42 GeV) !!! THINGS BIG AND SMALL

38. Particle physics at the energy frontier THINGS BIG AND SMALL

39. The many connections THINGS BIG AND SMALL

40. Conclusions • There’s mounting evidence for non-baryonic dark matter and dark energy. • These immediately imply physics beyond the SM. • Dark matter is likely to be at TeV scale. • Search for dark matter using • Collider experiments (LHC, ILC) • Direct searches (CDMS-II) • Indirect searches (ICECUBE) • Dark energy best investigated by JDEM (SNAP?). THINGS BIG AND SMALL

41. The larger US efforts From the report of the Quantum Universe subcommittee commissioned by HEPAP (DOE/NSF) THINGS BIG AND SMALL

42. The smaller US efforts From the report of the Quantum Universe subcommittee commissioned by HEPAP (DOE/NSF) THINGS BIG AND SMALL

43. HEPAP recommendation to DOE/NSF (by subpanel on Long Range Planning for U.S. HEP) THINGS BIG AND SMALL

44. Outlook • A large number of particle physics, astrophysics, and cosmology projects – both theoretical and experimental – are underway. They complement each other toward a common goal – to solve the most fundamental mysteries of nature. • It is a truly INTERNATIONAL effort. • We are living through a revolution in our understanding of the Universe on both the smallest and the largest scales. • The next decade or two will usher us into a new era of observation and comprehension. THINGS BIG AND SMALL

45. THANK YOU! Feel free to contact the speaker for more information dhiman@fnal.gov THINGS BIG AND SMALL