Spectral Slope Variability of BL Lac Objects in the Optical Band Fausto
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چکیده
Light curves of eight BL Lac objects in the BVRI bands have been analyzed. All of the objects tend to be bluer when brighter. However spectral slope changes differ quantitatively from those of a sample of QSOs analyzed in a previous paper (Trevese & Vagnetti 2002) and appear consistent with a different nature of the optical continuum. A simple model representing the variability of a synchrotron component can explain the spectral changes. Constraints on a possible thermal accretion disk component contributing to the optical luminosity are discussed. Subject headings: galaxies: active BL Lacertae objects: general BL Lacertae objects: individual (3C 66A, PKS 0422+004, S5 0716+71, OJ 287, ON 231, OQ 530, S5 1803+78, BL Lac) quasars: general
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Spectral Slope Variability of BL Lac Objects in the Optical Band
Light curves of eight BL Lac objects in the BVRI bands have been analyzed. All of the objects tend to be bluer when brighter. However spectral slope changes differ quantitatively from those of a sample of QSOs analyzed in a previous paper (Trevese & Vagnetti 2002) and appear consistent with a different nature of the optical continuum. A simple model representing the variability of a synchrotron...
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تاریخ انتشار 2003