Lecture 7 Jets on all scales Superluminal apparent
- Slides: 13
Lecture 7: Jets on all scales Superluminal apparent motions
Stellar Jets: visible in protostar phases, pc-scale, nonrelativistic, but supersonic (T-Tauri or Herbig-Haro objects)
Galactic sources: micro-quasars they are powered by stellar black holes, the kinematics is mildly relativistic: ~ 2 -3
Extragalactic Jets: radiogalaxies and blazars Lorentz factors ~ 10 -20 Virgo A (M 87) Cen A
Gamma-Ray Bursts: jets have been never resolved, but their presence is implied by the energetics. Lorentz factors: ~ 100 -1000 Isotropic irradiated –ray energy vs redshift Long GRB Short GRB “hybrids”
What is the observational evidence that blazars and GRBs are highly relativistic sources with strong special relativity aberration effects? 1) Large luminosities 2) Non-thermal spectra 3) superluminal motions (blazars, but also micro-QSO) 4) Gamma-ray transparency
Blazar 3 C 279 (z = 0. 54) The gamma-ray luminosity exceeds the Eddington limit For a 10^8 solar masses BH
Multiwavelength Spectrum of blazar Spectrum of GRB
VLBI monitoring of radio structures and blobs ~5 c Radio-blobs emitted at different epochs may have different apparent velocities, vapp = appc ~20 c 43 GHz; Jorstad et al. 2005 BL Lac 5 -10. 6 GHz; Mutel et al. 1990
VLBA observations at 7 mm (43 GHz) of BL Lac 5 c Marscher et al. 2008, Nature, 452, 966
Superluminal motion = 0. 999 ( = 22) = 0. 99995 ( = 100) = 0. 99 ( = 7) = 0. 9999 ( = 70) = 0. 95 = 0. 9 = 0. 7 = 0. 5
In micro-QSO one also observes the counterjet, so that both and viewing angle can be determined
C. M. Urry & P. Padovani 1995 Unified Schemes for Radio-Loud Active Galactic Nuclei PASP, 107, 803 G. B. Rybicki & A. P. Lightman 1979 Radiative Processes in Astrophysics I. F. Mirabel & L. F. Rodriguez 1999 Sources of Relativisiic Jets in the Galaxy Annual Review of Astronomy & Astrophysics 37, 409 L. Maraschi, G. Ghisellini, & A. Celotti 1992 A jet model for the gamma-ray emitting blazar 3 C 279 Ap. J, 397, L 5
