Intranight optical variability of TeV blazars with parsec-scale jets dominated by slow-moving radio knots

Vibhore Negi; Gopal-Krishna; Hum Chand; Silke Britzen

doi:10.1093/mnrasl/slad077

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arXiv · 2306.06170

Intranight optical variability of TeV blazars with parsec-scale jets dominated by slow-moving radio knots

Vibhore Negi·Gopal-Krishna·Hum Chand·Silke Britzen

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Abstract

BL Lac objects detected at TeV energies preferentially belong to the subclass called 'high-frequency-peaked' BL Lacs (HBLs). Parsec-scale radio jets in these TeV-HBLs often show dominant, slow moving radio knots that are at most mildly superluminal. We report the first systematic campaign to characterise the Intra-Night Optical Variability (INOV) of TeV-HBLs using a representative sample of 6 such sources, all showing a fairly high degree of optical polarization. Our campaign consists of high-sensitivity monitoring of this sample in 24 sessions of more than 3 hour duration each. For these TeV-HBLs, we find a striking lack of INOV and based on this, we discuss the importance of superluminal motion of the radio knots vis-a-vis the optical polarization, as the key diagnostic for INOV detection.

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Vibhore Negi, Gopal-Krishna, Hum Chand, Silke Britzen. 2023-06-09. Intranight optical variability of TeV blazars with parsec-scale jets dominated by slow-moving radio knots. https://doi.org/10.1093/mnrasl/slad077

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