1. THE KINEMATICS OF 1803+784 8th EVN SYMPOSIUM 26.09.2006 N.A. Kudryavtseva 1, S. Britzen 1, J. Roland 2, A. Witzel 1, E. Ros 1, A. Zensus 1, A. Eckart 3 1 MPIfR Bonn, 2 Institut d’Astrophysique, Paris, 3 I. Physikalisches Institut Universität zu Köln

2. Outline An Overview of enigmatic properties of the blazar 1803+784 Jet Kinematics in 1803+784 – possible rotating helical jet Different explanations for jet precession

3. 1803+784 Introduction BL Lac source z = 0.68 (Lawrence, 1987) Has quasi-periodical light curves Jet bending Misalignment between pc- and kpc- scales ~ 4 yrs Kelly et al., 2003 University of Michigan Radio Observatory Monitoring; Aller et al., 1996

4. 1803+784 Pc-Kpc scales Mas scale 10 mas scale Arcsec scale e.g.: Gabuzda et al.1992; Witzel et al.1988; Britzen et al.1999; Strom & Biermann 1991; Kollgaard et al.1992 Britzen et al., 2005

5. 1803+784 Introduction Evidence for a helical jet structure (Britzen et al., 2005) Indications for a helical magnetic field (Gabuzda et al. 1994; Gabuzda & Cawthorne 1996; Gabuzda et al. 2003) Evidence for a helical jet structure (Britzen et al., 2005) Indications for a helical magnetic field (Gabuzda et al. 1994; Gabuzda & Cawthorne 1996; Gabuzda et al. 2003)

6. 1803+784 VLBI Observations DATA 8 GHz 43 GHz 5 GHz 1.6 GHz 15 GHz 2.3 GHz Marcaide et al. 1985 Kellermann et al. 1998 Perez-Torres et al. 2000 Ros et al. 2000, 2001 Guirado et al. 2001 Britzen et al., 2005 Gurvits et al. priv. comm. 23 observational epochs From 1993 to 2006 Plus 52 epochs from literature 75 epochs of observations Plus 52 epochs from literature 75 epochs of observations Fey et al. 1996, Lobanov et al. 2000, Lister et al. 2001, Ros et al. 2001, Tateyama et al. 2002

7. 1803+784 Results Set of oscillating jet components Core separation is in the certain area Position angle changes with time C4C2Ca C1 C6

8. 1803+784 Results 1803+784, 15 GHz, Ca

9. 1803+784 Correlation of parameters For the inner components C0, C1, Ca and C2 we see correlation between parameters at 8 and 15 GHz Total flux density light curve, 8 GHzComponent C1’s parameters, 8 GHz

10. 1803+784 Position angle changes 8 GHz Δ p.a.=p.a.(max)–p.a. (min)

11. 1803+784 Position angle changes Flux density flares Peaks in p.a. spread 1988.861988.72 1991.741991.82 1993.561993.88 1998.341997.93 Period in Position angle spread: 4.0 years Period in coordinates of components: 7.1 years Period in total flux density light curves: 3.9 years Kelly et al.2003 Total flux [Jy] 1990 Time [yrs] 200020101980

12. 1803+784 Jet Rotation

13. 1803+784 Jet Rotation Presence of oscillating jet components Cyclical changes in the jet shape Jet rotation with the Period of ~ 7 yrs Speed ~18°/yr

14. 1803+784 Possible explanations Precession of the accretion disk  could be driven by a close massive object, e.g. Black Hole Fluid-dynamical instabilities in the interface between the jet material and the surrounding medium

15. Summary The source 1803+784 has a set of quasi- stationary jet components with the constant core separation and variable position angle The jet structure of 1803+784 can be explained with a rotating jet with a period of ~7 years

17. Jet Kinematics Introduction We are interested in investigation of the phenomena of jet wiggling and precession Investigation of possible reasons for jet precession such as binary black hole model and jet instabilities MOJAVE sample, Lister & Homan 2005 UMRAO, Aller et al., 1985 Michigan monitoring

18. 1803+784 Stationary Components 15 GHz 8 GHz

19. 1803+784 Stationary Components 5 GHz 8 GHz Literature data Fey et al. 1996, Lister et al. 2001, Tateyama et al. 2002, Ros et al. 2001, Lobanov et al. 2000

20. 1803+784 Jet Rotation Quasi-stationary jet components C1 and Ca show loops in the sky

21. 1803+784 Position angle changes 15 GHz 8 GHz

22. 1803+784 Speed of components + Correlations between position angle changes and the light curve Geometrical effect? Speed V app /c

23. 1803+784 Position angle changes Period in Position angle spread: 4.0 years Period in total flux density light curves: 2.0 and 3.9 years Kelly et al.2003 Period in coordinates of components: 7.1 years