Journal Article

The optical spectrum of PKS 1222+216 and its black hole mass

E. P. Farina, R. Decarli, R. Falomo, A. Treves and C. M. Raiteri

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 424, issue 1, pages 393-398
Published in print July 2012 | ISSN: 0035-8711
Published online July 2012 | e-ISSN: 1365-2966 | DOI:
The optical spectrum of PKS 1222+216 and its black hole mass

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We investigate the optical spectral properties of the blazar PKS 1222+216 during a period of approximately three years. While the continuum is highly variable [i.e. from λLλ(5100 Å) ∼ 3.5 × 1045 erg s−1 up to ∼15.0 × 1045 erg s−1] the broad line emission is practically constant. This supports a scenario in which the broad line region is not affected by jet continuum variations. We thus infer the thermal component of the continuum from the line luminosity and show that it is comparable with the continuum level observed during the phases of minimum optical activity. The mass of the black hole is estimated through the virial method from the full width at half-maximum of Mg ii, Hβ and Hα broad lines and from the thermal continuum luminosity. This yields a consistent black hole mass value of ∼6 × 108 M.

Keywords: galaxies: active; quasars: individual: PKS 1222+216

Journal Article.  4072 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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