1. ASTR 1040 – November 30 Planetarium, December 5
Last Observatory December 5
Third Mid-Term Exam December 7
Last Lecture December 14
Final Exam December 16
Website

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

3. 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/Mpc

4. 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

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

6. A Modern Hubble Diagram

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

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

9. 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

10. 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

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

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

13. More Galaxies

14. The Texture of the Universe

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

17. The Cosmic Web

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

19. Seyfert Galaxies

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

22. Huge Redshifts
The Brightest Objects in the Universe

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

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

26. The Most Distant Quasar z=5

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

28. 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.

29. 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.

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

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

33. Jets

35. Jets

36. Fields Twist to Make Narrow Jet

37. Radio Galaxies
Very Large Array
Very Large Baseline Array

39. Cygnus A

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

41. Wind Blows Jets

42. Full Model