Ringo2 Optical Polarimetry of Blazars

Helen Jermak, Iain Steele, Elina Lindfors, Talvikki Hovatta, Kari Nilsson, Gavin Lamb, Carole Mundell, Ulisses Barres De Almeida, Andrei Berdyugin, Ville Kadenius, Riho Reinthal, Leo Takalo
2016 Galaxies  
We present polarimetric and photometric observations from a sample of 15 γ-ray bright blazars with data from the Tuorla blazar monitoring program (KVA DIPOL) and Liverpool Telescope (LT) Ringo2 polarimeters (supplemented with γ-ray data from Fermi-LAT). We find that (1) The optical magnitude and γ-ray flux are positively correlated; (2) electric vector position angle rotations can occur in any blazar subclass; (3) there is no difference in the γ-ray flaring rates in the sample between
more » ... e between subclasses; flares can occur during and outside of rotations with no preference for this behaviour; (4) the average degree of polarisation (P), optical magnitude and γ-ray flux are lower during a rotation compared with during non-rotation; (5) the number of observed flaring events and optical polarisation rotations are correlated and (6) the maximum observed P increases from ∼10% to ∼30% to ∼40% for subclasses with synchrotron peaks at high, intermediate and low frequencies respectively. Light curves and polarisation curves for all 15 blazars can be found in [7] . The Fermi data are binned using the adaptive-binning scheme by [8] , where each bin has ∼20% flux uncertainty. This results in varying-length bin sizes depending on the brightness state of the source. Table 1. The full RINGO2 catalogue with redshift, source type, R band magnitude range, Polarisation range, Fermi range (for adaptive-binned data) and observation period information. Name z Type R Mag. Range Pol. Range (%) Fermi Range (ph·cm −2 ·s −1 ) Observation Period (MJD)
doi:10.3390/galaxies4040052 fatcat:37y4hwn65bcz7ot5catduu34di