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The Question

(Submitted April 09, 1997)

I'm a student of physics from Canada, and I was wondering how I could find out about quasars on a very detailed level.

The Answer

Since you know about black holes, I assume you know that quasars are a subset of a class of galaxies called active galactic nuclei (AGN) that are probably powered by a supermassive black hole. If you haven't already, check out "Active Galaxies" under "Advance High-Energy Astrophysics" at our Learning Center. If you are mostly interested in the physics of accretion onto a black hole, the standard text is "Accretion Processes in Astrophysics" by Frank, King and Raine.

On the other hand, if you are more interested in AGN in general, the basic textbook is "The Astrophysics of Gaseous Nebulae and Active Galactic Nuclei" by Osterbrock (the emphasis here is on optical spectra but it contains a lot of the physics of photoionzation which is important in AGN).

Quasars are AGN that are very luminous and radio-bright, and we think that in general they are radio-bright because we are seeing synchrotron emission from a jet of relativistic particles coming from the AGN. In radio-quiet AGN, either the jet is not present or it is directed away from us (since the particles are relativistic, the emission is beamed along the direction of the jet). There are some nearby radio galaxies that may be low-luminosity descendents of quasars, that show radio jets and evidence of many high energy particles (see books below). Blazars are an extreme case of quasars where we think we are looking directly into the jet.

A couple of books and articles on Radio Galaxies and Jets are:

  • Chapter 13 of "Galactic and Extragalactic Radio Astronomy", edited by G.L. Vershuur and K.I. Kellermann, 1988, Springer-Verlag.

  • "Beams and Jets in Astrophysics", by P.A. Hughes, c. 1991 Cambridge University Press

  • "Extragalactic Radio Jets" in Ann. Reviews of Astrophysics, 1984, 22:319-58 by A.H. Bridle and R.A. Perley

    Sincerely,

    Andy Ptak and Jonathan Keohane
    -- for Imagine the Universe!

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