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Cosmology and QSO’s

Cosmology and QSO’s. Edwin Hubble. Red Shift and Distance. 24 Mpc. 1200 km/s. 300 Mpc. 15,000 km/s. 780 Mpc. 39,000 km/s. 1220 Mpc. 61,000 km/s. Hubble’s Result. Modern Hubble’s Law. 2. 2. 1. 1. 3. 3. Raisin Cake Model. Velocity. Distance. Raisin Cake Model. Velocity

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Cosmology and QSO’s

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  1. Cosmology and QSO’s

  2. Edwin Hubble

  3. Red Shift and Distance 24 Mpc 1200 km/s 300 Mpc 15,000 km/s 780 Mpc 39,000 km/s 1220 Mpc 61,000 km/s

  4. Hubble’s Result

  5. Modern Hubble’s Law

  6. 2 2 1 1 3 3 Raisin Cake Model

  7. Velocity Distance Raisin Cake Model Velocity 1 cm/hr 2 cm/hr 3 cm/hr 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

  8. 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.

  9. 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

  10. Arno Penzias & Robert Wilson

  11. 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

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

  13. The Spectrum of 3C 273

  14. The RecordRed Shift La normally at 1216 Å

  15. 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?

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

  17. 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/l • If energy decreases, wavelength increases • Impossible to get the large red shifts required

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

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

  20. Gravitational Lensing

  21. Einstein Ring

  22. Active Galactic Nuclei

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

  24. Model of a Quasar • Supermassive Black Hole forms in the center of a galaxy • 108 - 109 M • Event Horizon size of solar system • Thick accretion disk fuels the activity • as disk thins quasar dims

  25. 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

  26. End of Section

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