1. Radio Galaxies and Quasars Powerful natural radio transmitters associated with Giant elliptical galaxies Demo

2. How we know distances to radio galaxies: redshifts (Doppler shifts) + Hubble’s Law

3. The discovery of quasars: a history lesson that teaches something about the universe Some of the brightest radio sources, 3C48, 3C273, did not seem to be associated with galaxies, but with star-like objects

4. Spectra of quasars showed strong emission lines, highly redshifted See Figure 24.2 of text Application of Hubble’s Law indicates enormously distant, Brilliant objects. But where are the galaxies?

5. With Hubble Space Telescope, we have imaged Quasars

6. What are quasars? Artistic view of an early quasar Physically what They are

7. Whether we see a radio galaxy or quasar depends on how we view them

8. In quasars and radio galaxies, there is a connection from the small to the extremely large: M87

9. M87 at radio wavelengths: it exists on many scales

10. The “Central Engines” of quasars and radio galaxies: black holes of 1 - 10 billion solar masses

11. Summary of Quasar Characteristics Clearly are a brilliant, energetic phenomenon in centers of galaxies Quasars are very distant. We see them as they were long ago Let’s look at the distribution of quasar redshifts

12. Question: what does this mean? 7236 quasars

13. Extragalactic Astronomy as a Time Machine

14. Observations of quasars and radio galaxies allow us to look out billions of light years into space NVSS survey of the sky at radio wavelengths found 1.8 million sources, almost all of which are radio galaxies and quasars The Sloan Digital Sky Survey (SDSS) measured positions, brightness, and spectra (therefore distances) of 675,000 galaxies and 90,000 quasars What do we see? What is the shape of the universe as a whole?

15. Galactic filaments and voids Figure 25.29 from book

16. Why are there filaments and voids in the distribution of galaxies?