RoboPol: do optical polarization rotations occur in all blazars?
We present a new set of optical polarization plane rotations in blazars, observed during the third year of operation of RoboPol. The entire set of rotation events discovered during three years of observations is analysed with the aim of determining whether these events are inherent in all blazars. It is found that the frequency of the polarization plane rotations varies widely among blazars. This variation cannot be explained either by a difference in the relativistic boosting or by selection effects caused by a difference in the average fractional polarization. We conclude that the rotations are characteristic of a subset of blazars and that they occur as a consequence of their intrinsic properties.
Additional Information© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 July 14. Received 2016 July 4. In original form 2016 April 19. First published online July 30, 2016. The RoboPol project is a collaboration between the University of Crete/FORTH in Greece, Caltech in the USA, MPIfR in Germany, IUCAA in India and Toruń Centre for Astronomy in Poland. The U. of Crete/FORTH group acknowledges support by the 'RoboPol' project, which is co-funded by the European Social Fund (ESF) and Greek National Resources, and by the European Commission Seventh Framework Programme (FP7) through grants PCIG10-GA-2011-304001 'JetPop' and PIRSES-GA-2012-31578 'EuroCal'. This research was supported in part by NASA grant NNX11A043G and NSF grant AST-1109911, and by the Polish National Science Centre, grant number 2011/01/B/ST9/04618. DB acknowledges support from the St. Petersburg University research grant 6.38.335.2015. KT acknowledges support by the European Commission Seventh Framework Programme (FP7) through the Marie Curie Career Integration Grant PCIG-GA-2011-293531 'SFOnset'. MB acknowledges support from NASA Headquarters under the NASA Earth and Space Science Fellowship Program, grant NNX14AQ07H. TH was supported by the Academy of Finland project number 267324. IM and SK are supported for this research through a stipend from the International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the Universities of Bonn and Cologne.
Published - MNRAS-2016-Blinov-1775-85.pdf
Submitted - 1607.04292v1.pdf