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Spectral Index Versus Frequency and Models for the Continua of AGN and QSOs

Published online by Cambridge University Press:  07 August 2017

Wayne A. Stein
Wayne A. Stein*
Affiliation:
University of Minnesota, School of Physics and Astronomy, 116 Church Street S.E., Minneapolis, Minnesota 55455

Abstract

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The observed spectral index as a function of frequency of QSO continua must be explained in models. It is generally increasing (F(ν) ∝ ν−α, α increasing) with higher frequency in the infrared (downward curvature). The visual to ultraviolet continuum has been shown to be a broken power law with F(ν) ∝ ν−0.5 at low frequency and a break to larger α at νo ∼ 3×1015 Hz. X-ray observations frequently exhibit a flat continuum with α < 1. One prominent example is 3C273 for which α1–3μm → 2, αvis ∼ 0.5 and αx ∼ 0.5. These spectral indices arise naturally in Secondary Electron Synchrotron Self-Compton (SESSC) models. Some accretion disk models approach these spectral indices for the visual-ultraviolet portion of the spectral distribution.

Type
Part 3: X-rays and the Central Source
Information
Symposium - International Astronomical Union , Volume 134: Active Galactic Nuclei , 1989 , pp. 201 - 202
Copyright
Copyright © Kluwer 1989 

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