Abstract:
We present the results obtained from our campaign to characterize the intra-night optical
variability properties of blazars detected by the Fermi large area telescope. This involves R-band
monitoring observations of a sample of 18 blazars, which includes five flat spectrum radio quasars
(FSRQs) and thirteen BL Lac objects (BL Lacs) covering the redshift range z ¼ 0:085 1:184. Our
observations carried out using the 1.3m J. C. Bhattacharya telescope cover a total of 40 nights ( 200 h)
between the period December 2016 and March 2020. We characterized variability using the power
enhanced F-test. We found duty cycle (DC) variability of about 11% for FSRQs and 12% for BL Lacs.
Dividing the sample into different sub-classes based on the position of the synchrotron peak in their
broadband spectral energy distribution (SED), we found DC of 16%, 10% and 7% for low
synchrotron peaked (LSP), intermediate synchrotron peaked (ISP) and high synchrotron peaked (HSP)
blazars. Such high DC of variability in LSP blazars could be understood in the context of the R-band
tracing the falling part (contributed by high energy electrons) of the synchrotron component of the
broadband SED. Also, the R-band tracing the rising synchrotron part (produced by low energy electrons)
in the case of ISP and HSP blazars, could cause lesser variability in them. Thus, the observed high DC of
variability in LSP blazars relative to ISP and HSP blazars is in accordance with the leptonic model of
emission from blazar jets.
