Iván Agudo. Astrometry of wobbling-blazar Scientific motivation and feasibility for VSOP-2

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Astrometry of wobbling-blazar blazar jet foot-points:

Agudo Instituto de Astrofísica de Andalucía (CSIC),

Perucho, J. L. Gómez, A Lobanov, A. Marscher, S.

1 Astrometry of wobbling-blazar blazar jet foot-points: Scientific motivation and feasibility for VSOP-2 Iván Agudo Instituto de Astrofísica de Andalucía (CSIC), Granada (Spain) with the collaboration of A. Roy. M. Perucho, J. L. Gómez, A Lobanov, A. Marscher, S. Jorstad, T. Krichbaum, U. Bach, M. Roca-Sogorb, and J. M. Martí

2 Astrometry of wobbling jet foot-points: Overview of the talk - Introduction What is jet wobbling? (phenomenology) The case of NRAO Motivation -Aims Relation to astrometric monitoring programs of jet foot points - The ongoing VLBA program Definition - Tech. results and feasibility for VSOP-2 - Summary

3 Astrometry of wobbling jet foot-points: Intro: What is jet wobbling? An increasing number of blazars have been reported to show either regular o irregular regular rotations of the structural position angle (SPA) of their jets in the plane of the sky (e.g., OJ 287, Tateyama & Kingham 2004; in 3C 273, Savolainen et al. 2006; in 3C 345, Lobanov & Roland 2005; in BL Lac, Stirling et al. 2003; in , Bach et al. 2005; in NRAO 150, Agudo et al. 2007). OJ 8 GHz Tateyama & Kingham. (2004)

4 Search Astrometry for the of origin wobbling jet foot of points: wobbling: jet foot-points: Introduction: Intro: What What is jet is is jet it? wobbling? An increasing number of blazars have been reported to show either regular o irregular regular rotations of the structural position angle (SPA) of their jets in the plane of the sky (e.g., OJ 287, Tateyama & Kingham 2004; in 3C 273, Savolainen et al. 2006; in 3C 345, Lobanov & Roland 2005; in BL Lac, Stirling et al. 2003; in , Bach et al. 2005; in NRAO 150, Agudo et al. 2007). 4C 15 GHz AGN jet curvatures and helical-like structures, both in parsec scales and at larger distances from the central engine, are also believed to be triggered by changes in direction of the innermost jet (e.g., in 3C 84, Dhawan et al. 1998; in 4C , Lister et al. 2003) Lister et al. (2003)

jet foot-points: Introduction: Intro: What What is jet is is jet it? wobbling?

5 Search Astrometry for the of origin wobbling jet foot of points: wobbling: jet foot-points: Introduction: Intro: What What is jet is is jet it? wobbling? This has been proposed to be related to regular precession behaviors with periods between 2 yr and 15 yr and jet structuralposition-angle changes with amplitudes (in the plane of the sky) between 20º and 50º. P 12 yr A 30º Tateyama & Kingham (2004) P 15 yr P 12 A yr 45º A 30º Savolainen et al. (2006) It is always detected in the innermost regions of the jets. 3C 345 P 9.5 yr A 40º BL Lac P 2.3 yr A 20º We will call to this phenomenon jet wobbling hereafter, and it is essentially what it is usually called jet precession Lobenov & Roland (2005) Stirling et al. (2003)

Astrometry of jet wobbling foot points: jet foot-points: Introduction: Intro: The The case case of of NRAO150 34 VLBA images at 43 GHz, covering 10 years, from mid 1997 to beginning of 2007 From our

6 Astrometry of jet wobbling foot points: jet foot-points: Introduction: Intro: The The case case of of NRAO VLBA images at 43 GHz, covering 10 years, from mid 1997 to beginning of 2007 From our programs, from VLBA archive, and from calibration observations of other monitoring programs (TXCam by Diamond and blazars by Marscher) The movie A point source until 1999 Afterwards, clear evidence of jet expansion to the south-east Jet expansion is accompanied by fast counter-clock-wise rotation of the jet on the plane of the sky

Astrometry of jet wobbling foot points: jet foot-points: Introduction: Intro: The The case case of of NRAO150 Q2 Jet expansion is accompanied by fast counter-clock-wise rotation of the jet on

7 Astrometry of jet wobbling foot points: jet foot-points: Introduction: Intro: The The case case of of NRAO150 Q2 Jet expansion is accompanied by fast counter-clock-wise rotation of the jet on the plane of the sky ~60º in 7yr ==> ~10º/yr Extreme case of jet wobbling Need to continue monitoring to follow possible change of sense and measure a possible quasi-period Agudo et al. (2007)

8 Astrometry of wobbling jet foot points: Motivation Jet wobblings, are observed in the innermost regions of the jets. The causes should be related to the properties of the inner jet, the accretion system, and the SMBH This makes jet wobbling studies an interesting potential tool for super-massive black hole, accretion and jet launching studies. Jet wobbling be triggered in principle by: a) disk precession, b) some other kind of more erratic disk/jet instabilities, or c) orbital motion of system However, here is still no general paradigm to explain the phenomenon Disk precession is nowadays the preferred assumed scenario to test and model jet wobbling phenomena (e.g. Valtonen, Lehto & Pietilä 1999, for OJ 287; Lister et al. 2003, for 4C+12.50; Stirling et al. 2003, for BL Lac; Caproni & Abraham 2004 for 3C 120; Liu & Melia 2002, for Sgr A* ; Caproni, Mosquera Cuesta & Abraham 2004, for a set of eight AGN) However, it is still under debate whether the observed jet wobbling is strictly periodic or not (see Mutel & Denn 2005 for the case of BL Lac). If not, this would point to erratic jet perturbations. Also, although it has some problems, the orbital motion of the jet nozzles can not be ruled out.

9 Astrometry of wobbling jet foot points: Aims First aim to conduct an systematic VLBI study of jet foot points: to look for the origin of jet wobbling and (afterwards) to extract information about the accretion system and the innermost regions of the jets We have started a new observational and numerical program to characterize the properties of different scenarios State-of-the-art multidimensional relativistic simulations (magnetohydrodynamic+ emission, and KH perturbation theory) (e.g. see Perucho et al.; VSOP-2 Symp 07). The numerical approach is essential to disentangle between the different phenomenologies related to these three scenarios, which are influenced by non-linear processes inherent to the RMHD flows. From the observational point of view, an important issue has not been taken into account up to now to approach the problem. Most of the previous VLBI data analysis assume that the jets wobble with respect to their cores, which are also assumed to have a fixed position on the sky.

10 Astrometry of jet wobbling foot points: jet foot Aims points: Aims 3C 120 RXTE This does not necessarily have to be true. In fact, Marscher et al. (2002) estimated a distance of the jet core to the central engine of the AGN in 3C 120 of ~0.3 pc. The same should apply to other sources Marscher et al. (2002) 0.3 pc Component Invisible jet region Radio core 7mm-VLBA

11 Astrometry of jet wobbling foot points: jet foot Aims points: Aims Any of the previously mentioned jet wobbling scenarios can produce systematic motion of the jet footpoints. Main observational goal: To measure how the initial jet position angle relates to absolute position of the jet foot point Regular Non-regular Regular Non-regular BH BH BH BH If observed, would help to distinguish between different causes for wobbling scenarios. Adequate numerical simulations of realistic jets are essential.

12 Astrometry of jet wobbling foot points: jet foot Aims points: Aims These observations can also provide independent geometrical constraints on the distance of the mm-core to the central compact object Regular Non-regular BH distance BH BH

13 Astrometry of wobbling jet foot-points: The ongoing VLBA program The main scientific and observational aims of an astrometric jet foot-point monitoring define the kind of observational program to be performed It is needed to observe: With the highest possible astrometric precision (i.e., inverse phase reference; determining the phase solutions on our strong target sources and transferring those to the position-reference calibrators) With 43GHz or higher (and 22 GHz; at least at 128 Mbps) Every 6-8 months (or even less for sort quasi-period sources of 2-4 yr.) We have started since Jul 2006 a 43GHz and 22 GHz VLBA phase reference program to monitor the absolute motion of the cores of the jets in NRAO150, OJ287, 3C273 and 3C345. We are observing: Switching between two position-reference calibrators (alternatively) With cycle times <120 s (~30 s on target source, ~ 50 s on the position-reference source, and and <20 s for slewing). With position-reference sources at angular distances between ~0.5º and ~2º and even at ~3.4º (for the case of OJ287) 43 GHz VLBA phase reference observations have already been demonstrated to be feasible even for sources at 5º (see Guirado et al. 2000)

14 Astrometry of jet foot points: Tech. Results and feasibility for VSOP-2 43 GHz VLBA images of 3C 273 Preliminary results show the good level of consistency between epochs, which is expected from successful astrometric observations within time scales lower than 1 yr (in the absence of component blending at the core due to new ejections) for P~15yr Jul Nov. This demonstrates that 43GHz VLBA phase reference with reference sources at up to 2-3º is possible and feasible 2007 Feb. Absolute position of the 3C 273 core Typical 43 GHz errors for such positions; ~60μas (Guirado et al. 2000); are symbolized by crosses.

15 Astrometry of jet foot points: Tech. Results and feasibility for VSOP-2 As it is not possible, ``a priori", to know the magnitude of the core absolute motion, a program like this one requires the highest astrometric precision with reference sources at 2-3º, (nowadays provided by the VLBA at 43 GHz) For the future: 43 GHz VSOP-2 observations (perhaps combined with 86 GHz phase reference monitoring programs) VSOP-2 project ASTRO-G VSOP-2 observations will be adequate: Long quasi-period sources (10-15 yr): Few observations (one every 4-8 months) VSOP-2 provide higher precision to prove jet foot-point motions Short quasi-period sources (e.g. 2-4yr): Dense time sampled observations (one every 2-4 months) VSOP-2 would provide definitive results for these sources in 3-4 years and with better precision than VLBA only

16 Astrometry of wobbling jet foot-points: Summary The ultimate origin of jet wobbling is not really known To know it, can enhance our knowledge of the properties of the SMBH, the accretion system, and the jet launching region Numerical simulations are important to characterize the different possible scenarios of jet wobbling The highest resolution phase reference VLBI experiments are essential to identify them in actual sources Ongoing VLBA observations have already demonstrated the feasibility of these observations at 43 GHz Adequate program for VSOP-2 (perhaps combined with 86 GHz phase reference)

Millimeter-Wave and Optical Polarimetric Behavior of Blazars

Millimeter-Wave and Optical Polarimetric Behavior of Blazars Iván Agudo Instituto de Astrofísica de Andalucía Granada (Spain) with: Clemens Thum José L. Gómez Sol Molina Carolina Casadio Helmut Wiesemeyer