For a new sample of 8 weak-line-quasars (WLQs) we report a sensitive search
in 20 intranight monitoring sessions, for blazar-like optical flux variations
on hour-like and longer time scale (day/month/year−like). The sample consists
exclusively of the WLQs that are not radio−loud and have either been
classified as `radio-weak probable BL Lac candidates' and/or are known to have
exhibited at least one episode of large, blazar−like optical variability.
Whereas only a hint of intra−night variability is seen for two of these WLQs,
J104833.5+620305.0(z = 0.219) and J133219.6+622715.9 (z = 3.15),
statistically significant inter−night variability at a few per cent level is
detected for three of the sources, including the radio-intermediate WLQ
J133219.6+622715.9 (z = 3.15) and the well known bona−fide radio−quiet
WLQs J121221.5+534128.0 (z = 3.10) and WLQ J153259.9−003944.1 (z = 4.62).
In the rest−frame, this variability is intra-day and in the far−UV band. On
the time scale of a decade, we find for three of the WLQs large brightness
changes, amounting to 1.655±0.009, 0.163±0.010 and 0.144±0.018 mag,
for J104833.5+620305.0, J123743.1+630144.9 and J232428.4+144324.4,
respectively. Whereas the latter two are confirmed radio-quiet WLQs, the
extragalactic nature of J104833.5+620305.0 remains to be well established,
thanks to the absence of any feature(s) in its available optical spectra. The
present study forms a part of our ongoing campaign of intranight optical
monitoring of radio quiet weak-line quasars, in order to improve the
understanding of this enigmatic class of Active Galactic Nuclei and to look
among them for a possible tiny, elusive population of radio-quiet BL Lacs.Comment: Accepted to MNRAS. 12 pages, 1 figure, 4 Tabl