2. Cosmology and QSO’s

3. Edwin Hubble

4. Red Shift and Distance 24 Mpc1200 km/s 300 Mpc15,000 km/s 780 Mpc39,000 km/s 1220 Mpc61,000 km/s

5. Hubble’s Result

6. Modern Hubble’s Law

7. Raisin Cake Model 1 2 3 1 2 3

8. Distance Distance from Home from Home (before baking)(after baking) 1 1 cm 2 cm 2 2 cm 4 cm 3 3 cm 6 cm Velocity 1 cm/hr 2 cm/hr 3 cm/hr Velocity Distance

9. Hubble’s Law to get Distance Measure the red shift of a galaxy  Compute the radial velocity Use Hubble’s Law to get the distance  Assumes that red shift is caused by radial velocity and that radial velocity is caused by the universal expansion.

10. Universal Expansion Space-Time itself is expanding  Carries galaxies along with it Conflicting cosmologies  Big Bang  Draw the expansion back in time until space-time occupies a point (13.7 billion years ago)  Steady State  Requires continual creation of matter

11. Arno Penzias & Robert Wilson

13. Quasi-Stellar Objects Extreme red shift  Using Hubble’s Law gives great distance  Visibility at these distances requires huge luminosity Almost star-like Variable  Using Light Time Argument gives size of solar system

14. QSO 3C 273 and its jet Red Shift of 16% Distance 800 Mpc Luminosity of 1000 normal galaxies

15. The Spectrum of 3C 273

16. L  normally at 1216 Å The Record Red Shift

17. Cosmological Hypothesis QSO’s are at the distance implied by Hubble’s Law  Most distant objects in the universe  Extreme luminosities But their light variations limits the size to roughly solar system  Emit as much light as 1000 large galaxies in the space of a solar system What is the energy source?

18. Local Hypothesis QSO’s are nearby  Distances of normal galaxies  Luminosities don’t have to be as great What causes the Red Shift?

19. The Red Shift Dilemma Mass ejection  Perhaps QSO’s are matter violently ejected from galactic nuclei. Recall M87  Why only Red Shifts? Gravitational Red Shifts  Light loses energy in escaping a gravity field  E = hf = hc/  If energy decreases, wavelength increases  Impossible to get the large red shifts required

20. Additional facts If QSO’s are very distant, we are seeing them as they were long ago. Gravitational lens

21. Quasar Gravitational Lenses Q 0957+561 Q 0142H 1413+117

22. Gravitational Lensing

23. Einstein Ring

24. Active Galactic Nuclei

25. Summary QSO are active galactic nuclei  Early stage of galaxy formation Velocity Distance QSO’s BL Lac Objects Seyfert Galaxies Normal Galaxies

26. Model of a Quasar Supermassive Black Hole forms in the center of a galaxy  10 8 - 10 9 M   Event Horizon size of solar system Thick accretion disk fuels the activity  as disk thins quasar dims

27. Normal Galaxies Harbor Supermassive Black Holes Measure luminosity of the nucleus  Mass in the form of stars  Brightness predicts mass Measure speed of the stars near the nucleus  Stars move under the influence of gravity  Gravity caused by mass at the nucleus Many galaxies have large, underluminous mass at the center

28. End of Section