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Distance Indicators to Low-Luminosity AGN

Published online by Cambridge University Press:  10 November 2010

G. Tenorio-Tagle
Affiliation:
Instituto de Astrofísica de Canarias, Tenerife
Itziar Aretxaga
Affiliation:
Royal Greenwich Observatory, Madingley Road, Cambridge CB3 OEZ, U.K.
Roberto J. Terlevich
Affiliation:
Royal Greenwich Observatory, Madingley Road, Cambridge CB3 OEZ, U.K.
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Summary

Variability is one of the most conspicuous properties of AGN. The starburst model postulates that the variability observed in radio-quiet sources is produced by the supernova (SN) and compact supernova remnant (cSNR) activity resulting from the evolution of a metal-rich massive stellar cluster, product of a starburst in the nucleus of an early-type galaxy. In this context, the optical light curves of AGN are reproduced by a random sequence of SN events. The parameters that describe a given light curve are the overall rate of explosions (νSN), the energy released in each cSNR (∊51), and the density of the circumstellar medium in which the remnants evolve (n7). In the case of low-luminosity AGN (MB ≳ −22 mag) these three parameters are well constrained by the observations: νSN by the minimum of luminosity and/or by the number of peaks of the light curves; ∊51 by the amplitude and duration of typical oscillations in the light curve and/or by the equivalent width of recombination lines, such as Hβ; and n7 by the decay rate of well-isolated peaks (Aretxaga & Terlevich 1993). The physics involved in the parameters above provides two independent constraints on the distance to a low-luminosity AGN.

Firts distance indicator: SN rate versus stellar luminosity

The B-band luminosity arising from a coeval cluster at its SN II explosion phase, 10 to 60 Myr, is mainly due to Main Sequence stars and cSNR.

Type
Chapter
Information
Violent Star Formation
From 30 Doradus to QSOs
, pp. 343 - 344
Publisher: Cambridge University Press
Print publication year: 1994

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