1. ASTR 1200 Announcements Exam 3 Returned Today
Two more lectures in B180 after this.
Final Exam Wednesday Dec 17 1:30-4:00
In Benson 180
Website

2. The Distance Scale

3. Redshift of Galaxies Hubble found that galaxies are redshifted.
The absorption lines are
those of the stars that
make up the galaxy.

4. The Redshift z = 0 implies local
z of 1 or more implies near far edge of universe

5. Hubble’s Law The more distant the galaxy, the greater the redshift.
The more distant is the galaxy,
the faster it is flying away from
us.
H0=70 km/s/Mps

6. Example Galaxy in Virgo Cluster is at 15Mpc
will recede at v = 70 km/s/Mpc x 15Mpc = 1050km/s
dl = l x v/c = 4000Å x 1050/300,000 = 14Å
a 4000Å line will appear at 4014Å

7. Example 2
l0 = 1216Å but is observed at l = 1228Å
dl = 12

8. A Modern Hubble Diagram

9. Galaxies are Flying Apart
Galaxies remain same size. They just get farther apart.
Effect is the same no matter which position you occupy

10. Expanding Universe Current Universe The volume of the universe is
increasing.
Early Universe

11. The Age of the Universe Notice: At time zero, d = 0
All galaxies are at zero distance!
The universe has zero volume!
when t=1/H

12. The Beginning Before 13 billion years ago, there was no before.
Time and space started with the Big Bang
We will return to this in a few more lectures

13. Galaxies are Moving
Gravity attracts them to mass centers.

14. Redshift Survey Galaxies across the sky. Distance from redshift.
“The Great Wall”

15. More Galaxies

16. The Texture of the Universe

18. Theory of Structure Structure grew out of minor fluctuations.
Gravity causes density regions
to enhance.
The very origin of structure.

19. The Cosmic Web

20. Active Galactic Nuclei
Seyfert Galaxies 1948
Radio Galaxies 1954
Quasars
BL Lac’s
Blazars
They’re all manifestations of the same thing.

21. Seyfert Galaxies

22. Quasar QUAsi Stellar Radio source  Quasar (Sometimes QSO)
Completely enigmatic

24. Huge Redshifts
The Brightest Objects in the Universe

26. Quasar Spectrum Originally found from radio But not all have radio.
Broad spectral output from radio to gamma-ray

27. In a Galaxy Far, Far Away Long, Long Ago

28. The Most Distant Quasar z=5

29. Host Galaxies Quasars are in host galaxies
Mostly just outshine the entire galaxy

30. The AGN Model The Nucleus of the Galaxy is the Clot of Stars
around the giant black hole that’s fallen to the bottom
of the galaxy gravitational well.
As more material falls in, the black hole grows and the
nucleus can get very bright.
I think all major galaxies have a BBH (big black hole) in the center.
This is yet to be proven. Certainly a substantial fraction do.

31. Feeding a Quasar Accretion disk is formed of stars
and clouds that wander too near the
big black hole.
Tidal forces rip them apart.
They settle into an accretion disk.
When there’s no material falling in,
the quasar goes quiet.

32. Spectrum Width of line implies velocities of 30,000km/s !
High Orbital Speed implies deep gravitational well.

34. AGN Accretion Disk Simulations @ 0.1as
Courtesy of Phil Armitage, U. Colorado and C. Reynolds, U. Maryland

35. Jets

37. Jets

38. Fields Twist to Make Narrow Jet

39. Radio Galaxies
Very Large Array
Very Large Baseline Array

41. Cygnus A

42. Radio Lobes Lobes contain 1053 Joules of energy
in relativistic electrons.
Mass energy equivalent
of a million stars!

43. Wind Blows Jets

44. Full Model

45. Superluminal Expansion
Radio interferometers
see blobs emitted by
AGN’s from base of jet.
Watch them expand.
Know distance, so can
measure speed.
v = 900,000km/s
v = 3c
Superluminal ! ?
Is Einstein’s ghost worried?

46. Phase Velocity Point of impact can move v > c
Nothing traveling that fast.

47. Better Explanation Blob moves close to speed of light toward us.
Its closer later.
Makes sideways motion appear speeded up.

48. Quasar Absorption Lines

49. The Intergalactic Medium

50. Intergalactic Medium
70% of the regular matter in the universe is between the galaxies
Was probably neutral, then re-ionized
Somehow got oxygen and other heavy elements.
We didn’t know it was there 20 years ago.
Still don’t have any clue how it works.
Cutting edge of research.

51. The Cosmic Web