1. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 1 Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 25 & 26

2. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 2 Prep for Today (Is now due) – L26 Reading: –Required: BBBHNM: Chapter 20 eLearning Quizzes: –Chapters 2-18 Reading questions: –Two questions from Chapter 20 Papers: –Paper 4 CPR due Wednesday at Noon –Paper 5 due one week after we finish Chapter 20 NOT the last day of class

3. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 3 Course Evaluations This semester course evaluations will be done online "Department of Physics On-Line Course Evaluation System“ http://evaluation.tamu.edu/ Please, take a few minutes to fill these out. I really appreciate it!

4. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 4 Unit 6 Going back in time and going forward in time Before the first millionth of a second and the Fate of the Universe

5. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 5 Outline of Unit 6 1.Possible Fates of the Universe 2.The Case for Dark Matter 3.Particle Physics and Dark Matter 4.Inflation 5.Dark Energy Today

6. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 6 Summarizing the Data so Far 1.Redshifts of Galaxies gives us the speed of expansion fairly accurately 2.The measured mass of the “stars and stuff” gives about 4% of the critical density 3.The Cosmic Background Radiation is consistent with a density of 100% of the critical density Something is inconsistent…

7. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 7 The Story There is a strong case to be made that there is Matter and Energy in the Universe we can’t “see” directly The Evidence for Dark Matter –Today Particle Physics and Dark Matter –The Standard Model and Supersymmetry –Next time

8. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 8 Today’s Lecture The Case for Dark Matter 1.The Rotation of Galaxies 2.Gravitational Lensing 3.Colliding Galaxies

9. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 9 What is Dark Matter and why do we call it Dark Matter? What do we see when we look at the Heavens? Our eyes see photons, but with other detectors we can see electrons, protons, atoms and neutrinos All these things interact with photons  we can “see” them because they produce the light we observe

10. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 10 Dark Matter If there is something else out there it must not interact with light very much Call this “Dark Matter”

11. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 11 Evidence 1 Watch the way stars rotate around the center of Galaxies

12. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 12 The Planets and the Sun General Relativity does a good job of predicting the planets path around the sun assuming virtually all the mass of the Solar system is located at the Sun –Only small influence due to the small masses of the other planets

13. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 13 What about Stars and Galaxies? Can again use General Relativity to predict the orbits of stars as they move around the galaxy Should look like a complex collection of individual stars all in separate free orbits around the heart of the galaxy Problem: This isn’t what the data shows

14. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter The Data 14

15. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 15 Does this work for Stars? Simulation without Dark Matter Simulation with lots of Dark Matter particles in the galaxy http://bigbang.physics.tamu.edu/Figures/StolenAnimations/galrot_anim.gif Watch how fast a star rotates around the center of the galaxy… Data looks like this

16. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 16 Stuff Outside the Stars? Can also look at the clouds of hydrogen on the outskirts of the galaxy Also rotating faster than they should be Looks like they are feeling the gravity of a large amount of mass we can’t “see”

17. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 17 Dark Matter? Data well explained by lots of “Dark Matter” we can’t see Mostly clumped at the center due to gravity Lots of it in a “halo” around the entire galaxy

18. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 18 Evidence 2 Look at the gravitational impact on light that travels through the Universe towards us

19. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 19 General Relativity and Light The large mass of the Sun can bend the path of light Result: The apparent position of a star “moved” as the light passed from outer space, past the Sun, and to us Light’s path in curved space time Is here“Looks” like its here

20. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 20 Looking at Light from the Universe Galaxy Light from a Galaxy Looks like a Galaxy Hydrogen Cloud Looks like a Galaxy behind a cloud of hydrogen Looks like a Galaxy behind a cloud of heavy “stuff” that isn’t just stars and hydrogen Another Galaxy

21. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 21 Lensing of Galaxies Dark Matter “Lenses” the galaxies behind them like a prism Evidence that the light coming to us is passing through lots of matter we can’t see directly Prism

22. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 22 More on Lensing Sometimes we can even see more than one image of the same galaxy!

23. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 23 Evidence 3 Colliding Clusters of Galaxies

24. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 24 Look at Colliding Clusters of Galaxies Atoms Dark Matter Atoms Dark Matter Atoms in the Galaxies interact and slow down as they pass through each other Dark Matter doesn’t interact much so it isn’t slowed down much

25. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 25 Colliding Galaxy Clusters Atoms and Dark Matter Atoms and Dark Matter The atom part and the Dark Matter part of Galaxies interact differently as they pass through each other Atoms Dark Matter

26. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 26 Colliding Galaxy Clusters Atoms and Dark Matter Atoms and Dark Matter Atoms Dark Matter Light from a Galaxy Galaxy

27. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 27 Evidence for This in Nature? Colliding Clusters of Galaxies Blue is the part from lensing only “Fast  Dark Matter” Red part from observing the light “Slow  Atoms”

28. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 28 http://bigbang.physics.tamu.edu/Figures/StolenAnimations/bullett_anim_lg.mpg

29. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 29 What IS Dark Matter? We don’t know… Still working on it…

30. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter Prep for Next Time – P25 Reading –Required: BBBHNM Chapter 20 Reading questions –Two questions from Chapter 20 eLearning Quiz –If we finished Chapter 19 then end-of- chapter quiz 19 Papers –Paper 3 revisions due Tuesday at noon if you want –Paper 4 due Wednesday at 11:55PM

31. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter Prep for Next Time – P26 Reading –Required: BBBHNM Chapter 20 Reading questions –Two questions from Chapter 20 eLearning Quiz –If we finished Chapter 19 then end-of- chapter quiz 19 Papers –Paper 4 CPR due Wednesday at Noon –Paper 5 due one week after we finish Chapter 20 NOT the last day of class

32. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter Full set of Readings So Far Required: –BBBHNM: Chaps. 1-20 Recommended: –TFTM: Chaps. 1-5 –BHOT: Chaps. 1-7, 8 (68-76), 9 and 11 (117-137), 12 –SHU: Chaps. 1-3, 4(77-86), 5(95- 114), 6-8 (up-to-page 164) –TOE: Chaps. 1-3 –Seeds (Cosmology in the 21 st Century)

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34. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 34 http://bigbang.physics.tamu.edu/Figures/StolenAnimations/dark_matter_lg.mpg

35. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 35 For Next Time Could the Dark Matter just be a bunch of a single type of new fundamental particle? Chap 20: Particle Physics –The Standard Model of Particle Physics –Supersymmetry Full reading for Unit 6: BBBHNM: Chaps. 18-22 SHU: 8 (159-164) BHOT: 11 (122-137), 12 Seeds (Cosmology in the 21 st Century, Web Handout) Full reading through Unit 6: BBBHNM: Chaps. 1-22 TFTM: Chaps. 1-5 BHOT: Chaps. 1-7, 8 (68-76), 9 and 11 (117-137), 12 SHU: Chaps. 1-3, 4(77-86), 5(95-114), 6-8 (up-to-page 164) TOE: Chaps. 1-3 Seeds (Cosmology in the 21 st Century) Lecture prep: Turn in on eLearning Two questions from Chapter 20 you want to know the answer to

36. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 36 The Data

37. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter Papers Paper 1 is done Paper 2 grades are on eLearning –All grades fixed, revision paper grades posted Paper 3: –We have fixed papers for calibration problems –Still mis-graded? Let us know! –Do CPR if you submitted a revision Paper 4: –Was due today before class Paper 5 (last paper, no final) –Assigned after we start Chap 20 37

38. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter Other Stuff Elearning: –Unit 5 has Unit 6 questions (sigh…) –5 and 6 will both be due last day of class Schedule from here on out –Today: Ch 19 & 20 (paper 4 due) –Wed Apr 21: No class, Muster –Mon Apr 26: Ch 20 &21 (paper 4 CPR due) –Wed Apr 28: Ch 21 & 22 –Mon May 3: Ch 22 (last day of class, paper 5 due) 38

39. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 39 The Reading for Unit 6 Full reading for Unit 6: BBBHNM: Chaps. 18-22 SHU: 8 (159-164) BHOT: 11 (122-137), 12 Seeds (Cosmology in the 21 st Century, Web Handout) Full reading through Unit 6: BBBHNM: Chaps. 1-22 TFTM: Chaps. 1-5 BHOT: Chaps. 1-7, 8 (68-76), 9 and 11 (117-137), 12 SHU: Chaps. 1-3, 4(77-86), 5(95-114), 6-8 (up- to-page 164) TOE: Chaps. 1-3 Seeds (Cosmology in the 21 st Century)

40. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 40 Evolution of The Universe Put it all together and there is significant evidence that there is LOTS of dark matter in the Universe

41. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 41 Writing Assignments Short Assignments 1, 2 & 3 Re-do’s are still possible. Want to revise again? Talk to me eLearning: Unit 5 past due Need to be working on Unit 6

42. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 42 Last Paper Due last day of class 1.If you did the Black Hole paper your paper is posted now, on Dark Matter 2.If you did not do the Black Hole paper you must turn in a Research Paper Turn in at eLearning like usual

43. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 43 Ok… What Does it Look Like? Stars look more like they are turning as if they are part of a single solid, giant wheel Looks like this wheel would be MUCH more massive than the sum of all the stars in the galaxy Also, much more spread out than most of the mass at the center

44. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 44 Does this work for Stars? http://bigbang.physics.tamu.edu/Figures/StolenAnimations/galrot_anim.gif Watch how fast a star rotates around the center of the galaxy…

45. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 45 Evidence 4 Is the universe made up of just the known particles? –Electrons? –Protons? –Neutrons? –Neutrinos? Perhaps its just known particles we can’t see? –The Earth doesn’t shine…

46. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 46 Composed of Normal Matter? Lots of “protons and neutrons” we can’t see? Look at the amount of Deuterium and Lithium in the Universe The data predict that normal matter is only ~4% of the critical density Consistent with other observations

47. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 47 Does this work for Stars? Watch how fast a star rotates around the center of the galaxy…

48. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 48 Does this work for Stars? Watch how fast a star rotates around the center of the galaxy…

49. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 49 How the Earth looks to Light… Path doesn’t curve Path does curve

50. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 50 What is the Evidence for Dark Matter?

51. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 51 Need a picture here… TCP Figure 21.1, page 614 ? Shockwave video comparing galaxy rotation with and without dark matter

52. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 52 Dark Matter Combined mass of all “visible” matter (i.e. emitting any kind of radiation) in the universe adds up to much less than the critical density. Gravitational lensing shows that some clusters contain 10 times as much mass as is directly visible.

53. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 53 From this we can conclude (but not prove) that much of our galaxy’s mass must lie beyond the distance of the Sun’s orbit around the galactic center, and distributed throughout the galaxy’s spherical halo Most of the light comes from the center Thus, there is a large amount of matter that we can’t see

54. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 54 Rotation Stuff However, there is lots of “dark matter” that we cannot see directly but which we know must be there

55. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 55 SHU 8 cont… This “dark, unseen matter must have so much mass that it held the stars in position, making them the shining hub of a giant invisible wheel”

56. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 56 TCP 21 One of our favorite reasons is to look at the atomic hydrogen clouds in the Milky Way. The clouds lay very far out from the galactic center (further out than our sun) and are rotating faster than they should be if they were just feeling the gravity of the mass we can “see”

57. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 57 There had to be part of the galaxy which were just not seeing, and that this must make up far more of the total mass of the galaxy than the stars we could observe shining

58. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 58 Why do we believe? Why do we believe there is other stuff out there that we can’t see? Three reasons 1.The way stars rotate around the center of Galaxies 2.Look at the gravitational impact on light that travels through the Universe towards us 3.Colliding Galaxies

59. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 59 Two Topics We can use the evidence that we live in a Flat, Homogenous and Isotropic Universe as evidence for two main things 1.Other Mass/Energy in the Universe (This Time) 2.Inflation (Coming Soon)

60. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 60 Evidence that we live in a Flat, Homogenous and Isotropic Universe and its implications If we live in a flat Universe where is the rest of the Mass/Energy that makes up the rest of the “critical Density” Missing Mass and Energy in the Universe and the case for Dark Matter

61. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 61 Outline SHU 8 first part TCP 21, but not really…

62. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 62 “If you assumed that all the stars we can see in the galaxy are free to affect each other gravitationally in exactly the same way gravity governs the dynamics of the solar system, then our galaxy should rotate differently than we observe them to…

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64. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 64

65. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 65 Nature of baryonic dark matter still very uncertain and speculative. Baryonic Dark Matter One component: MAssive Compact Halo Objects = “MACHOs”: Small compact objects (e.g., brown dwarfs, small black holes) acting as gravitational lenses. Earth Brightness of background star Time Distant background star MACHO

66. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 66 TCP 21 cont… The universe has two possible fates: It might continue to expand forever, or it might someday stop expanding and begin to collapse We don’t yet know the fate of the universe because the answer depends on the overall density of matter in the universe – and we cannot determine the overall density until we first determine how much dark matter is out there Finished?

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68. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 68 This is some text

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73. Big Bang, Black Holes, No Math Early Times & Fate of The Universe Topic 2: Dark Matter 73 Dark unseen matter surrounding the galaxy like a halo