Gabriele Giovannini Marcello Giroletti Gregory B. Taylor

1. The jet of Markarian 501 from the sub-parsec to the kpc scale Gabriele Giovannini Marcello Giroletti Gregory B. Taylor Dipartimento di Astronomia, Bologna University Istituto di Radioastronomia, INAF Bologna Dept. of Physics and Astronomy, Univ. of New Mexico

2. z = 0.034 1mas = 0.67 pc Tavecchio et al. 2001 From NED

3. Mkn 501 –Large Scale Koolgaard et al. 1992 VLA Symmetric structure Jets are no more relativistics on 10 kpc scale 20 kpc

4. At 2 arcsecond β cosθ > 0.36 At 1 arcsecond β cosθ > 0.63 VLA B array (Cassaro et al. 1999) VLAA array at 1.4 GHz 1.5 kpc 1.5 kpc

5. At100 mas:β cosθ > 0.61 At 50 mas: β cosθ > 0.77 HPBW = 9x5 mas 35 pc

6. The jet shows a complex and continuous morphology with many sharp bends before undergoing a last turn in the PA of the kpc scale structure. The jet is clearly limb brightened. At 10 mas: β cosθ > 0.92 15 pc

7. Evident limb-brightened structure beginning very near to the core and visible up to 100 mas from it. It is interpreted as evidence of a velocity structure. No proper motion has been found comparing 9 different epochs from 1995.29 to 1999.55. Compact structures are resolved and complex in high resolution images 10 pc 22 GHz 22 GHz 1.5 pc 1.6 GHz VSOP 3 pc

8. A radio core + one sided jet is visible in recent VLBI observations at 86.2 GHz with a linear resolution of 0.08 x 0.13 pc (HPBW) Giroletti et al. in prep. 0.2pc Thanks to the global mm VLBI network: VLBA (7 telescopes), Eb, Plateau de Bure, Pico Veleta, Onsala, Metsahovi

9. Core: unresolved at 86 GHz  size lower than 0.03 pc (gaussian fit) 1 Rs = 0.001 pc(M = 109 Mo) High frequency spectrum is steep with a turnover at about 8.4 GHz. It implies a magnetic field in the range 0.01 – 0.03 G and that inside the “core” a structure is present Question:why the jet brightness is so low in the 86 GHz image? Steepening because of high magnetic field? We do not have polarization information Gabuzda et al. 2004: B fields are dominated by the toroidal component.

10. Better images to: find the core position measure the jet dynamics (starting velocity and acceleration + velocity structure) M87 at 86 GHz (Krichbaum et al. 2006) at 43 GHz (VLBA) (Ly et al. 2007) MKN501 at 86 GHz 0.08 pc

11. Jet velocity and orientation from data: High velocity jet with Γ =15 and θ = 4o (δ 15) in the gamma-ray region (< 0.02 mas < 0.02 pc) – from high frequency emission, gamma-ray variability, and SED (SSC models) In the radio jet region the jet orientation move from 4o to 10o - 15o to explain the limb-brightened structure radio structure and Γ decrease to 10 (δ 2.6) at 30 - 40 mas from the core (80-120 pc) The jet velocity decrease is low: from HSA data we estimate relativistic jets (v > 0.6 c at 1” from the core) At 5” (10 kpc de-projected) the jet is no more relativistic (Γ= 1.02 v = 0.2c) as expected from FR I jet velocities Jet PA not constant for unknown reasons

12. Observational data are in agreement with a simple adiabatic model if the magnetic field is mostly perpendicular to the jet (a parallel field predicts a too fast velocity decrease with respect to the j cj ratio) Jet initial velocity 0.998 c 25 20 15 10 5 Adiabatic model in the case of relativistic motion discussed by Baum et al. 1997. See also Cotton et al. 1999, and Giroletti et al. 2004

13. THANK YOU