We performed a new analysis of B and R light curves of a sample of PG quasars. We confirm the variability-redshift correlation and its explanation in terms of spectral variability, coupled with the increase of rest-frame observing frequency for quasars at high redshift. The analysis of the instantaneous spectral slope for the whole quasar samples indicates both an inter-QSO and an intra-QSO alpha-luminosity correlation. Numerical simulations show that the latter correlation cannot be entirely due to the addition of the host galaxy emission to a nuclear spectrum of variable luminosity but constant shape, implying a spectral variability of the nuclear component. Changes of accretion rate are also insufficient to explain the amount of spectral variation, while hot spots possibly caused by local disk instabilities can explain the observations.

Trevese, D., & Vagnetti, F. (2002). Quasar spectral slope variability in the optical band. THE ASTROPHYSICAL JOURNAL, 564(2 I), 624-630 [10.1086/324541].

Quasar spectral slope variability in the optical band

VAGNETTI, FAUSTO
2002

Abstract

We performed a new analysis of B and R light curves of a sample of PG quasars. We confirm the variability-redshift correlation and its explanation in terms of spectral variability, coupled with the increase of rest-frame observing frequency for quasars at high redshift. The analysis of the instantaneous spectral slope for the whole quasar samples indicates both an inter-QSO and an intra-QSO alpha-luminosity correlation. Numerical simulations show that the latter correlation cannot be entirely due to the addition of the host galaxy emission to a nuclear spectrum of variable luminosity but constant shape, implying a spectral variability of the nuclear component. Changes of accretion rate are also insufficient to explain the amount of spectral variation, while hot spots possibly caused by local disk instabilities can explain the observations.
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore FIS/05 - Astronomia e Astrofisica
English
Con Impact Factor ISI
Galaxies: active; Galaxies: photometry; Galaxies: Seyfert; Quasars: general
Trevese, D., & Vagnetti, F. (2002). Quasar spectral slope variability in the optical band. THE ASTROPHYSICAL JOURNAL, 564(2 I), 624-630 [10.1086/324541].
Trevese, D; Vagnetti, F
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2108/44722
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