Astro 103 - Lecture 19 Summary

Lectures Lecture page Astro103 page

Quasars and Their Evolution (in a nut-shell)



Quasars are extremely luminous active galactic nuclei

- their luminosities imply 0.1-1000 M/year fall into a massive black hole

- they are rare objects


Two possible evolution scenarios:

(i) quasars are long-lived (large fraction of age of Universe),

Ultra-massive central black holes in a few galaxies today

(ii) quasars are short-lived (1 Gyr or less)

Moderately massive central black holes in most galaxies today



Difficult to study quasar (or galaxy) evolution because astronomers tend to collect apparent-brightness limited samples

nearby objects are low-luminosity

distant objects are high-luminosity

This effect masks or mimics the effects of evolution


Lectures Lecture page Astro103 page
Last updated: Nov 28, 2001 Matthew A. Bershady