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Insights on Relativistic Jets from Faraday Rotation

Bob Zavala USNO Flagstaff Station Greg Taylor, Gabrielle Giovannini. Insights on Relativistic Jets from Faraday Rotation. VLBA Capabilities. Freqs: 330 MHz to 86 GHz (90cm to 3mm) Baselines: 236km to 8600km Angular resolution: 22 mas to 0.2 mas Limited to non-thermal sources (high T B )

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Insights on Relativistic Jets from Faraday Rotation

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  1. Bob Zavala USNO Flagstaff Station Greg Taylor, Gabrielle Giovannini Insights on Relativistic Jets from Faraday Rotation

  2. VLBA Capabilities Freqs: 330 MHz to 86 GHz (90cm to 3mm) Baselines: 236km to 8600km Angular resolution: 22 mas to 0.2 mas Limited to non-thermal sources (high TB) synchrotron emission masers

  3. VLBI Polarimetry • Cotton et al. 1984-1st VLBI pol. Image • Application to relativistic jets • Preferred vector orientations assumed negligible Faraday rotation

  4. RM = neB||L 3C120 R. C. Walker 1.66 GHz

  5. Rotation Measure Survey • RM survey of 40 AGN from Kellermann et al. 1998 survey • Flux density > 2 Jy @ 15 GHz • 27 quasars, 7 BL Lac, 4 RG, 2 ? • 8, 12 & 15 GHz RM survey

  6. 3C 279 8-15 GHz

  7. 3C 279 4.5 years 8-15 GHz RM %pol

  8. M87 sub-parsec structure

  9. The Faraday screen • small spatial, temporal scales • In host galaxy not a foreground effect

  10. Screen properties • ne < 30,000 cm-3 • Use 1000 cm-3 • 0.3 < L < 10 pc • 1000 rad/m2, 1 pc, B|| = 1mG

  11. STScI

  12. 3C273 12-22 GHz

  13. RM gradient 5 parsecs

  14. Thermal Faraday screen No mixing of thermal and relativistic gas

  15. Other RM gradients 4 BL Lacs: Gabuzda et al. (2004) 3C 273 core: Homan et al. (2005) Quasar 0333+321: Asada et al. (2006) K. Asada

  16. Sources without RM gradients Mrk 501, quasar 1611+343

  17. Summary Screen Scale size ~ 1 pc B ~ 1μG Helical fields: broad jets not always present? protons mixed in later?

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