A large rotation of the polarization angle of the TeV Blazar W Comae
1 Instituto de Astronomía, Universidad Nacional Autónoma de México, AP 70-264, 04510 DF, Mexico
2 Instituto de Astronomía, Universidad Nacional Autónoma de México, AP 877, 22800, Ensenada BC, Mexico
Published online: 9 December 2013
Optical R-band polarimetric variability observations of the TeV Blazar W Comae are presented. Data obtained from 2008 February to 2013 May (∼5.2 years) are analyzed. The source presented a maximum flux variability of ∼3 mJy. The minimum variability time scale displayed by the source during the monitored period is Δt ∼ 3.3 d. A maximum linear polarisation degree value of P= (33.8 ± 1.6)% was observed in 2013 May 12. A rotation of the position angle from 78° (2008 March 10) to 229° (2008 July 11) was observed. This rotation corresponds to a large change of Δθ ∼ 150° in a period of 123 d or to a rotation of ∼1.2° per day. After the high activity state observed in 2008, the position angle shows a preferential value of ∼ 56°, with variations of ∼60-120°. From the Stokes parameters we infer the existence of two optically-thin synchrotron components that contribute to the optical polarized flux. One of them is stable, with P∼11%.
© Owned by the authors, published by EDP Sciences, 2013
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.