Journal Article

The nature of the intranight variability of radio-quiet quasars

B. Czerny, A. Siemiginowska, A. Janiuk and A. C. Gupta

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 386, issue 3, pages 1557-1567
Published in print May 2008 | ISSN: 0035-8711
Published online April 2008 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.13131.x
The nature of the intranight variability of radio-quiet quasars

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We select a sample of 10 radio-quiet quasars with confirmed intranight optical variability and with available X-ray data. We compare the variability properties and the broad-band spectral constraints to the predictions of intranight variability by three models: (i) irradiation of an accretion disc by a variable X-ray flux, (ii) an accretion disc instability, (iii) the presence of a weak blazar component. We concluded that the third model, e.g. the blazar component model, is the most promising if we adopt a cannonball model for the jet variable emission. In this case, the probability of detecting the intranight variability is within 20–80 per cent, depending on the ratio of the disc to the jet optical luminosity. Variable X-ray irradiation mechanism is also possible but only under additional requirement: either the source should have a very narrow Hβ line or occasional extremely strong flares should appear at very large disc radii.

Keywords: accretion, accretion disc; black hole physics; instabilities; galaxies: active; quasars: general

Journal Article.  8313 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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