Intranight optical variability of blazars

Ram Sagar, ; Stalin, C. S. ; Gopal-Krishna, ; Wiita, Paul J. (2004) Intranight optical variability of blazars Monthly Notices of the Royal Astronomical Society, 348 (1). pp. 176-186. ISSN 0035-8711

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We present results of a multi-epoch intranight optical monitoring of 11 blazars consisting of six BL Lac objects and five radio core-dominated quasars (CDQs). These densely sampled and sensitive R-band CCD observations, carried out from 1998 November to 2002 May during a total of 47 nights with an average of 6.5 h per night, have enabled us to detect variability amplitudes as low as ~1 per cent on intranight time-scales. A distinction is found for the first time between the intranight optical variability (INOV) properties of the these two classes of relativistically beamed radio-loud active galactic nuclei (AGNs). BL Lacs are found to show a duty cycle (DC) of INOV of ~60 per cent, in contrast to CDQs, which show a much smaller INOV DC of ~20 per cent, the difference being attributable mainly to the weakly polarized CDQs. On longer time-scales (i.e. between a week to a few years) variability is seen from all the CDQs and BL Lacs in our sample. The results reported here form part of our long-term programme to understand the intranight optical variability characteristics of the four main classes of luminous AGNs, i.e. radio-quiet quasars (RQQs) and radio lobe-dominated quasars (LDQs), as well as CDQs and BL Lac objects.

Item Type:Article
Source:Copyright of this article belongs to Royal Astronomical Society.
Keywords:Galaxies: Active; Galaxies: Jets; Galaxies: Photometry; Quasars: General
ID Code:13132
Deposited On:11 Nov 2010 06:48
Last Modified:16 May 2016 22:21

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