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Broadband properties of active galactic nuclei


Edelson, Richard (1987) Broadband properties of active galactic nuclei. Dissertation (Ph.D.), California Institute of Technology.


NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.

The broadband radio-infrared-optical-ultraviolet properties of active galactic nuclei are used to investigate the nature of the central engine and the surrounding environment. Optically selected quasars (which have [...] = [...]) and Seyfert 1 galaxies ([...] = [...]) tend to have relatively flat infrared spectra and low reddenings, while most Seyfert 2 galaxies ([...] = [...]) and other dusty objects have steep infrared spectra and larger reddenings. The infrared spectra of most luminous radio-quiet active galaxies turn over near [...]80 [...]. It appears that the infrared spectra of most quasars and luminous Seyfert 1 galaxies are dominated by unreprocessed radiation from a synchrotron self-absorbed source of order a light day across, about the size of the hypothesized accretion disk. Seyfert 2 galaxies and other reddened objects have infrared spectra which appear to be dominated by thermal emission from warm ([...]50 K) dust, probably in the disk of the underlying galaxy. A broad emission feature, centered near 5 [...], is present in many luminous quasars and Seyfert 1 galaxies.

Highly polarized objects ("blazars") can be strongly variable at far-infrared wavelengths over time scales of months. There is no conclusive evidence for far-infrared variations in normal (low-polarization) quasars or Seyfert galaxies, although low-level flickering (at the [...]30% peak-to-peak level) cannot be ruled out.

Seyfert galaxies tend to have steep radio spectra ([...]). The radio spectra of Seyfert 1 galaxies often flatten out near 2 cm. There is no significant difference in the mean radio luminosities of Seyfert 1 and 2 galaxies. There are of order 10[...] Seyfert galaxies/Gpc[...], most of which have 6 cm luminosities between 10[...] and 10[...] ergs/s and 60 [...] luminosities between 10[...] and 10[...] ergs/s. The Seyfert 2 galaxy radio luminosity function cuts off sharply below 10[...] ergs/s.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Astronomy
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Schmidt, Maarten (advisor)
  • Moffet, Alan Theodore (advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:12 November 1986
Record Number:CaltechETD:etd-09092008-113501
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3413
Deposited By: Imported from ETD-db
Deposited On:17 Sep 2008
Last Modified:26 Dec 2012 02:59

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