Optical microvariability of EGRET blazars

We present results of a photometric CCD study of the incidence of microvariability in the optical emission of a sample of 20 blazars detected at gamma-ray energies by the EGRET instrument of the Compton Gamma-Ray Observatory. We have observed strong outbursts in some sources, but many others display...

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Autores principales: Romero, Gustavo Esteban, Cellone, Sergio Aldo, Combi, Jorge Ariel, Andruchow, Ileana
Formato: Articulo
Lenguaje:Inglés
Publicado: 2002
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Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84617
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Sumario:We present results of a photometric CCD study of the incidence of microvariability in the optical emission of a sample of 20 blazars detected at gamma-ray energies by the EGRET instrument of the Compton Gamma-Ray Observatory. We have observed strong outbursts in some sources, but many others displayed no significant variability on timescales of hours. The typical minimum timescale is found to be of ∼several hours, not tens of minutes as claimed by some authors. The duty cycle for optical intranight microvariations of gamma-ray blazars, as estimated from our observations, seems to be ∼50%, lower than what is usually assumed. For night-to-night variations, instead, the duty cycle approaches that observed in radio-selected BL Lacs and flat-spectrum radio quasars (i.e. ∼70%).