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292 6 MACRO– AND MICRO–JETS DRIVEN BY BLACK HOLES 6.6.1 Core–Jets Parsec–scale jets can only be detected by means of VLBI techniques. Since the jets are obviously relativistic on this scale, they appear as one–sided (due to relativistic Doppler beaming), including a stationary core and knots moving away from this core at superluminal speeds. Figure 139: A VLBA image of 3C 120 at a frequency of 22 GHz (Walker et al. 1996). The scale is in milliarcseconds (mas). (At the distance of 3C 120, 1 mas corresponds to a length of 0.7 parsecs = 2.3 light-years.) 3C 120: In Fig. 139 we show the structure of the parsec–scale jet of the radio galaxy 3C 120 at 22 GHz (1 mas = 0.7 parsecs for a Hubble constant of 65 km/s/Mpc). There is an unresolved stationary feature on the left (eastern) end, customarily called the core. Bright spots (termed blobs by experts) move down the jet. Of particular interest is a bright blob that emerges from the core after a major outburst in brightness (flux density) in early 1998 (Fig. 149). The speeds of the superluminally moving components range from 3.5 to 8.3 times the speed of light. The magnetic field behavior is complex, changing with both position and time. The
6.6 Structure and Emission of Micro–Jets 293 core, however, is usually unpolarized. 2 6.6.2 Emission Properties As the brightest and nearest quasar (z = 0.158), 3C 273 is an ideal laboratory to study emission processes for jets in quasars. This source displays significant flux variations, has a well measured wide band spectral energy distribution and has a relativistic jet emanating from the central part in a galaxy. This collimated jet structure extends up to 150 kpc from the core, depending on the unknown inclination towards the observer. 3C 273 is classified as a blazar – though I find this notion somewhat misleading – and is also a prominent gamma–ray source. 3C 273 and the hard X–ray emission: Recently, the results of a long–term monitoring of 3C 273 with RXTE have been published (Kataoka et al. 2002). This covers the longest observation period in the hard X–rays (about 835 ksec, Fig. 140). Most of the 3C 273 photon spectra observed between 1996 and 2000 can be fitted Figure 140: RXTE light curves of 3C 273 in the hard X–rays (Katakoa et al. 2002). The data are binned in 10 days intervals. by a power–law spectrum with spectral index αX = 1.6 ± 0.1. This is consistent with previously published data. Multifrequency spectra provide information for physical quantities relevant to the jet physics, e.g. the magnetic field, the size of the emission region, the maximum energy and the density of relativistic electrons. 2 For a movie see http://www.bu.edu/blazars/3C120.html
Page 1 and 2: CONTENTS 265 Contents 6 Macro- and
Page 3 and 4: 6 Macro- and Micro-Jets Driven by B
Page 5 and 6: 6.1 DRAG(o)Ns - FR I and FR II 269
Page 11 and 12: 6.2 Jets as Super(magneto)sonic Col
Page 13 and 14: 6.2 Jets as Super(magneto)sonic Col
Page 15 and 16: 6.3 Fundamental Parameters for Jets
Page 17 and 18: 6.3 Fundamental Parameters for Jets
Page 19 and 20: 6.4 A 3-Phase Model for Kiloparsec-
Page 25 and 26: 6.5 Relativistic Jet Propagation 28
Page 27: 6.6 Structure and Emission of Micro
Page 31 and 32: 6.6 Structure and Emission of Micro
Page 37 and 38: 6.7 Formation of Micro-Jets 301 6.7
Page 39 and 40: 6.7 Formation of Micro-Jets 303 Fig
Page 41 and 42: 6.7 Formation of Micro-Jets 305 Thi
Page 43 and 44: 6.7 Formation of Micro-Jets 307 VLB
Page 45 and 46: 6.7 Formation of Micro-Jets 309 as
Page 53 and 54: 6.7 Formation of Micro-Jets 317 the
Page 55 and 56: 7.1 The Dark Age 319 Figure 152: Da
Page 57 and 58: 7.3 The First Quasars 321 Figure 15
Page 59 and 60: 7.3 The First Quasars 323 Bromm & L
Page 61: REFERENCES 325 [17] Leahy, P. 1993,

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