1. 18 - Structure of the Universe

2. Extragalactic Distance Scale Cepheids M V =-3.35logΠ-2.13+2.13(B-V) Π=period (days) Novae M V (max)=-9.96-2.31log(Δm/day) first 2 mags Planetary Nebulae Luminosity Function M 5007 (brightest)=-4.48 Globular Cluster Luminosity Function M B (turnover)=-6.5 Tully-Fisher M H =-10.01log(2v r /sin i)+3.61 D-σ logD=1.333logσ + C (for relative distances) Brightest Red Supergiants M V =-8.0 SN Ia M B (max)=-19.6 (but correct for decline time and redshift) Brightest Galaxy in Cluster M V =-22.82 Surface Brightness Fluctuations

3. Cepheid Distance Scale L ’ s for PL relation from Cluster Fitting and a few (~6?) measured parallaxes 1997 (Feast & Catchpole) - Hipparcos parallaxes for 223 Cepheids, of which 26 carry a lot of weight (accurate π ’ s and spread in P) PLC relation due to width of instability strip (Sandage) Dependent on metallicity Affected by extinction (in near-IR brightnesses are less, too). Blending light with nearby stars Different methods give different results

5. Globular Cluster Luminosity Function

6. Planetary Nebula Luminosity Function

7. Tully-Fisher Relation (in near-IR)

8. D-σ Relation (recently brightness- D-σ = “ fundamental plane ” )

9. Brightest Galaxy in Cluster

10. Supernovae Ia ’ s

11. Correcting for stretch and time dilation 35 SN Ia ’ s 1-day averages Original Data Corrected for Time Dilation (redshift z) Corrected for Stretch

13. Slipher (1914-1925) - Radial Velocities of Galaxies Most ( “ nearby ” ) galaxies exhibit spectral shift to longer wavelengths - “ redshifts ”

14. Universal Expansion

15. Note: data originally published in 1929 PNAS, not 1936! 1929 - Hubble enters the picture

16. The Hubble Law These are valid only for small z. For larger z, need to use true relativitstic formulation: This gives the Hubble Law (for space with flat geometry - which it seems to be) as: actually first introduced by Lamaitre in 1927

17. NOTE Implications: This sort of law would be derived by any observer in the universe - everyone sees the same law. Everything is (overall) moving away from everything else at the same rate per unit distance. Universe is expanding - space is expanding, carrying the matter with it. The universe need not have a “ center ” for this to be true. The age of a universe with no acceleration/deceleration is simply 1/H 0. If universal, such a law allows one to determine the distance of an object from its value of z.

18. Hubble & Humason 1931 extend Hubble Law to larger distances

19. H 0 from SN Ia ’ s WMAP gives H 0 =71

20. Large-Scale Structure (on many scales) Groups (N<50, D~2 Mpc) Clusters (N~50 ( “ poor ” ) - thousands ( “ rich ” ), D~8 Mpc) “ regular ” - spherical & centrally condensed (Coma) “ irregular ” - not (Virgo) Superclusters - clusters of clusters

21. The Local Group

22. M 81 Group M 82 M 81 NGC 3077

23. M 81 Group in H I

24. M82 Chandra (X-rays) VLA & Merlin (radio) RGB

25. Leo I Group (M 96 Group)

26. Virgo Cluster

27. Coma Cluster

28. Dark Matter 1933 - Fritz Zwicky uses the virial theorem to deduce the existence of “ dunkle Materie ” (dark matter) in the Coma cluster. Helvetica Physica Acta, 6, 110 (1933)

29. “ Method iv involves the observation of gravitational lens effects. Measurements of deflecting angles combined with data on the absolute distance of the “ lens nebula ” from the observer suffice to determine the mass of the lens nebula. The chances for the successful application of this method grow rapidly with the size of the available telescopes. ” - Zwicky, ApJ, 86, 217 (1937). Considers the possibility there may be “ internebular matter ” that is giving mass estimates of clusters of galaxies too high a value. Considers independent methods to get masses of individual galaxies... M/L for Coma ~500, compared to ~3 locally.

30. Hot Intergalactic Gas X-ray emission from Perseus Cluster. Probably >50% of all baryonic matter. Accounts for a fraction of the “ dark matter ”. The rest is “ non- baryonic ”.

31. Red: radio synchrotron Blue: X-rays

32. Local Supercluster

33. Even LARGER Scale Structure CfA - single slice

35. CfA “ hockey puck ” “ Great Wall ” Local Supercluster Pisces-Perseus supercluster

37. Density fluctuations & Non-Hubble Flow

39. Origin of Structure - Cold Dark Matter

40. Lensing & Dark Matter

43. Red: X-ray emitting gasBlue: Lensing material

44. HUDF - Beckwith et al. (Nov. 2006 AJ 132, 1729-1755)

45. Galaxy Evolution Filters