1 / 22

Recollimation Shock, Transverse Waves and the Whip in BL Lacertae

Recollimation Shock, Transverse Waves and the Whip in BL Lacertae. M.H. Cohen Caltech. M onitoring O f J ets in A ctive Galaxies with V LBA E xperiments. MOJAVE Collaborators. M. Lister (P.I.), J. Richards (Purdue)

samuru
Download Presentation

Recollimation Shock, Transverse Waves and the Whip in BL Lacertae

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Recollimation Shock, Transverse Waves and the Whip in BL Lacertae M.H. Cohen Caltech Granada 13 vi 2013

  2. Monitoring Of Jets in Active Galaxies with VLBA Experiments MOJAVE Collaborators • M.Lister (P.I.), J. Richards (Purdue) • T. Arshakian (Univ. of Cologne, Germany) • M. and H. Aller (Michigan) • M. Cohen, T. Hovatta, (Caltech) • D. Homan (Denison) • M. Kadler, M. Böck (U. Wurzburg, Germany) • K. Kellermann (NRAO) • Y. Kovalev (ASC Lebedev, Russia) • A. Lobanov, T. Savolainen, J. A. Zensus (MPIfR, Germany) • D. Meier (JPL) • A. Pushkarev (Crimean Observatory, Ukraine) • E. Ros (Valencia, Spain) Very Long Baseline Array The MOJAVE Program is supported NASA Fermi Grant NNX08AV67G 2 Granada 13 vi 2013

  3. BL Lac Topics • Components, Ridge Line • Recollimation Shock • PA Variations: Wobble • Transverse Waves • Wave Speeds • Relaxation in 2010: Wiggle • Conclusions 3 Granada 13 vi 2013

  4. Components • Components are a small number of elliptical Gaussians • that sum to the image. They usually are circular. • A component is often a bright spot in the image. • Components are tracked in time, if the cadence • of observations is fast enough. 4 Granada 13 vi 2013

  5. Ridge Line • BL Lac is elongated and has a ridge. • Most components move downstream • along the ridge (±0.1 mas) 5 Granada 13 vi 2013

  6. Ridge Line and Components 2005.71 2006.86 Granada 13 vi 2013

  7. Several New Components per YearMax Speed 10.6c Granada 13 vi 2013

  8. BL Lac Component Tracks quasi-stationary recollimation shock 8 Granada 13 vi 2013

  9. Recollimation Shock • Component 7 = recollimation shock • Analogy to M87, 3C120 • Simulation (Lind et al 1999, ...) shows a‘magnetic chamber’ and fast cpts ejected into a ‘nose cone’ (not full 3D RMHD) (Meier p715) • Need strong toroidal component in the magnetic field 9 Granada 13 vi 2013

  10. z vmax dist from core • 3C 120 0.033 5.3c ~ 5 mas • 3.1 * 80 mas ~ 3x107 rg • M 87 .00436 4.3 ** >= 106 rg • BL Lac .0686 10.6 # ~ 106 rg • * downstream from C1 Agudo et al 2012 • ** downstream from HST1 Cheung et al 2007 • # downstream from cpt 7 MOJAVE Recollimation Shock II 10 Granada 13 vi 2013

  11. BL LacPosition Angle vs Epoch Granada 13 vi 2013

  12. Transverse Wave 2004 - 2007 A B B A V ≈ 1.15 mas yr-1 ≈ 4.8 c Granada 13 vi 2013

  13. Shifted Ridge Lines Granada 15 vi 2013

  14. Transverse Waves 1999-2000 V ≈ 0.80 mas yr-1 ≈ 3.3 c Granada 15 vi 2013

  15. Transverse Wave 2000-2001 15 Granada 13 vi 2013

  16. Component 16 Advected with the Transverse Wave 16 Granada 13 vi 2013

  17. Several New Components per YearMax Speed 10.6c Granada 13 vi 2013

  18. BL Lac Component Tracks quasi-stationary recollimation shock Centerline PA=166o 18 Granada 13 vi 2013

  19. BL Lac 2010.8-2012.8wiggle PA ≈ 171o Granada 15 vi 2013

  20. BL LacConclusions I • Strong quasi-stationary component is identified as • a recollimation shock. • Distance from core ~ 106 rg • Superluminal components appear to come from • or through the recollimation shock. Granada 13 vi 2013

  21. BL LacConclusions II • Jet supports transverse waves. • Waves have superluminal speed. • Waves are correlated with swings in the inner PA. • Components are advected with the transverse motion. • Jet acts more like a rope than a water hose. • When wave activity dies down, a stable wiggle appears. Granada 13 vi 2013

  22. Conclusions III These observations support a model in which the jet contains a strong toroidal magnetic field. Transverse waves (Alfven?) are excited by PA swings of the nozzle, and propagate superluminally downstream, as large-scale wiggles on the ridge line. The superluminal components (fast MHD waves?) stay on the ridge, and can be advected transversely. In 2009 the waves died down, and a small-scale stationary wiggle appeared on the jet. Granada 13 vi 2013 22

More Related