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Astrophysical Jets

Astrophysical Jets. Robert Laing (ESO). Jets are everywhere. Gamma-ray burst. Young stellar object. Galactic black-hole binary system. Jets in Active Galaxies. … with an emphasis on the nearby Well-collimated, bulk relativistic flows with Γ > 5 Powered by accretion onto black

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Astrophysical Jets

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  1. Astrophysical Jets Robert Laing (ESO)

  2. Jets are everywhere Gamma-ray burst Young stellar object Galactic black-hole binary system

  3. Jets in Active Galaxies … with an emphasis on the nearby Well-collimated, bulk relativistic flows with Γ > 5 Powered by accretion onto black holes M 106 - 1010 MSUN Powers can be as high as 1041 W Major effects on galaxy formation and cluster evolution Efficient accelerators: electrons 1014 eV; ? protons >1020 eV

  4. Jets in radio galaxies – up to Mpc scales FRI – low power Deceleration Morphological Classification Correlates with radio luminosity FRII – high power Relativistic and supersonic until hot-spots

  5. Key topics • Where are the emission sites? What are the radiation mechanisms? • Jet velocity fields • Effects on galaxy formation and cluster evolution • Composition, power thrust • Formation and collimation mechanism

  6. Emission from jets: broad-band and on many scales Auger Radio - TeV Gamma ray Synchrotron and inverse Compton → broad electron energy distribution + B Protons? Cen A - X-ray synchrotron

  7. Relativistic effects in jets Energy spectrum Doppler boosting Doppler factor Jet/counter-jet ratio Aberration Superluminal motion Blazars (θ 0) are bright, and rapidly-varying Low-power radio galaxies are side-on TeV blazars vapp = 30c

  8. M87 TeV - core or HST-1 Look for correlated variability with both core and HST-1

  9. Jet velocity fields Kovalev et al. 2007 Limb-brightening and slow component speeds: gradual acceleration or fast spine + slow shear layer?

  10. Acceleration → deceleration? Hardcastle et al. 2003 NGC315 Tingay et al. Cotton et al. 1999 RL et al. 2006 TeV results require very high Γ - where are jets accelerated?

  11. Velocity fields on large scales VLA data θ = 58o Model

  12. Velocity β = v/c: deceleration and transverse gradients NGC 315 3C296 B2 0326+39 3C 31

  13. Environmental Impact shock 1061 erg 380 kpc Wise et al. 07 Hydra A

  14. Low Radio Frequency Traces Energy Feedback from jets halts cooling in cores of galaxy clusters Quenching of star formation → major influence on galaxy formation (“downsizing”) Radio: Lane et al. 04/Taylor Wise et al. 07 74 MHz

  15. Composition? • Electromagnetic • Leptonic (pair plasma) - not near black hole • Hadronic (electron-proton plasma; relativistic protons?) Composition must change along the jet. EM → particles Entrainment of external medium • Faraday rotation? • Bulk Comptonization • Mass, energy, momentum budget

  16. Sunyaev-Zeldovich Effect and Radio Lobe Composition Perseus cluster (NGC1275/3C84) Contours: radio Colour: X-ray Extra pressure component Simulation of ALMA observation of SZ decrement in Perseus cluster Bubble profiles for different lobe compositions Pfrommer, Ensslin & Sarazin (2005)

  17. Pressure and density 3C31 0326+39 3C296

  18. Mach number and entrainment rate Stars Jets must be very light: consistent with electron-positron plasma

  19. Power estimates from cavities

  20. M87 86GHz 174 Rs Limits on collimation from mm VLBI Jet base 70 x 20 RS Krichbaum et al. 2006

  21. Magnetic collimation?

  22. mm VLBI Coming shortly .... we hope eMERLIN EVLA LWA, eLOFAR VSOP-2 GLAST ALMA

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