Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 23 & 24

1. Big Bang, Black Holes, No MathASTR/PHYS 109Dr. David TobackLecture 23 & 24

2. 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

3. 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) 3

4. 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 21st 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 21st Century)

5. Unit 6 Going back in time and going forward in time Before the first millionth of a second and the Fate of the Universe

6. Outline of Unit 6 • Possible Fates of the Universe • The Case for Dark Matter • Particle Physics and Dark Matter • Inflation • Dark Energy Today

7. Summarizing the Data so Far • Redshifts of Galaxies gives us the speed of expansion fairly accurately • The measured mass of the “stars and stuff” gives about 4% of the critical density • The Cosmic Background Radiation is consistent with a density of 100% of the critical density Something is inconsistent…

8. 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

9. Today’s Lecture The Case for Dark Matter • The Rotation of Galaxies • Gravitational Lensing • Colliding Galaxies Note: SHU is a little out of date…

10. 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

11. Dark Matter • If there is something else out there it must not interact with light very much • Call this “Dark Matter”

12. Evidence 1 Watch the way stars rotate around the center of Galaxies

13. 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

14. 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

15. The Data

16. Does this work for Stars? Watch how fast a star rotates around the center of the galaxy… Simulation without Dark Matter Simulation with lots of Dark Matter particles in the galaxy Data looks like this http://bigbang.physics.tamu.edu/Figures/StolenAnimations/galrot_anim.gif

17. 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”

18. 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

19. Evidence 2 Look at the gravitational impact on light that travels through the Universe towards us

20. 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 Is here “Looks” like its here Light’s path in curved space time

21. Looking at Light from the Universe Galaxy Light from a Galaxy Another Galaxy Hydrogen Cloud Looks like a Galaxy behind a cloud of heavy “stuff” that isn’t just stars and hydrogen Looks like a Galaxy behind a cloud of hydrogen Looks like a Galaxy

22. Lensing of Galaxies Prism • 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

23. More on Lensing Sometimes we can even see more than one image of the same galaxy!

24. Evidence 3 Colliding Clusters of Galaxies

25. Look at Colliding Clusters of Galaxies Atoms in the Galaxies interact and slow down as they pass through each other Atoms Atoms Dark Matter doesn’t interact much so it isn’t slowed down much Dark Matter Dark Matter

26. Colliding Galaxy Clusters The atom part and the Dark Matter part of Galaxies interact differently as they pass through each other Atoms and Dark Matter Atoms and Dark Matter Atoms Atoms Dark Matter Dark Matter

27. Colliding Galaxy Clusters Galaxy Galaxy Galaxy Light from a Galaxy Atoms and Dark Matter Atoms and Dark Matter Atoms Atoms Dark Matter Dark Matter

28. 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”

29. http://bigbang.physics.tamu.edu/Figures/StolenAnimations/dark_matter_lg.mpghttp://bigbang.physics.tamu.edu/Figures/StolenAnimations/dark_matter_lg.mpg

30. http://bigbang.physics.tamu.edu/Figures/StolenAnimations/bullett_anim_lg.mpghttp://bigbang.physics.tamu.edu/Figures/StolenAnimations/bullett_anim_lg.mpg

31. What IS Dark Matter? We don’t know… Still working on it…

32. 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 21st 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 21st Century) Lecture prep: Turn in on eLearning Two questions from Chapter 20 you want to know the answer to

33. End of Lecture

34. Evolution of The Universe Put it all together and there is significant evidence that there is LOTS of dark matter in the Universe

35. 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 35

36. Last Paper Due last day of class If you did the Black Hole paper your paper is posted now, on Dark Matter If you did not do the Black Hole paper you must turn in a Research Paper Turn in at eLearning like usual 36

37. 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

38. Does this work for Stars? Watch how fast a star rotates around the center of the galaxy… http://bigbang.physics.tamu.edu/Figures/StolenAnimations/galrot_anim.gif

39. 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…

40. Composed of Normal Matter? 0 • 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

41. Does this work for Stars? Watch how fast a star rotates around the center of the galaxy…

42. Does this work for Stars? Watch how fast a star rotates around the center of the galaxy…

43. How the Earth looks to Light… Path doesn’t curve Path does curve

44. What is the Evidence for Dark Matter?

45. Need a picture here… • TCP Figure 21.1, page 614 ? • Shockwave video comparing galaxy rotation with and without dark matter

46. Dark Matter 0 • 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.

47. 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

48. Rotation Stuff • However, there is lots of “dark matter” that we cannot see directly but which we know must be there

49. 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”

50. 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”