Open AccessIntranight optical variability of blazars
Author(s) -
Sagar Ram,
Stalin C. S.,
Wiita Paul J.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07339.x
Subject(s) - physics , blazar , quasar , astrophysics , active galactic nucleus , duty cycle , amplitude , bl lac object , light curve , astronomy , galaxy , gamma ray , optics , voltage , quantum mechanics
ABSTRACT 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.