ﻻ يوجد ملخص باللغة العربية
The RoboPol instrument and the relevant program was developed in order to conduct a systematic study of the optical polarisation variability of blazars. Driven by the discovery that long smooth rotations of the optical polarisation plane can be associated with the activity in other bands and especially in gamma rays, the program was meant to investigate the physical mechanisms causing them and quantify the optical polarisation behaviour in blazars. Over the first three nominal observing seasons (2013, 2014 and 2015) RoboPol detected 40 rotations in 24 blazars by observing a gamma-ray-loud and gamma-ray-quite unbiassed sample of blazars, providing a reliable set of events for exploring the phenomenon. The obtain datasets provided the ground for a systematic quantification of the variability of the optical polarisation in such systems. In the following after a brief review of the discoveries that relate to the gamma-ray loudness of the sources we move on to discuss a simple jet model that explains the observed dichotomy in terms of polarisation between gamma-ray-loud and quite sources and the dependence of polarisation and the stability of the polarisation angle on the synchrotron peak frequency.
The RoboPol program has been monitoring the $R$-band linear polarisation parameters of an unbiased sample of 60 gamma-ray-loud blazars and a control sample of 15 gamma-ray-quite ones. The prime drive for the program has been the systematic study of t
We present ~2000 polarimetric and ~3000 photometric observations of 15 gamma-ray bright blazars over a period of 936 days (11/10/2008 - 26/10/2012) using data from the Tuorla blazar monitoring program (KVA DIPOL) and Liverpool Telescope (LT) RINGO2 p
The parsec-scale radio properties of 232 active galactic nuclei (AGNs), most of which are blazars, detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline
To search for optical variability on a wide range of timescales, we have carried out photometric monitoring of 3C 454.3, 3C 279 and S5 0716+714. CCD magnitudes in B, V, R and I pass-bands were determined for $sim$ 7000 new optical observations from 1