Alma Mater Studiorum Universit`a degli Studi di Bologna ... - Inaf

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124 6. Faraday rotation in two extreme environments 124
Summary and conclusions The goal of this thesis was to constrain the strength and structure of the magnetic field associated with the extragalactic medium surrounding radio galaxies located in a variety of environments by using observations of Faraday rotation and depolarization. To interpret the RM structure, I have derived analytical models and performed two- and three-dimensional Monte Carlo simulations. The picture that emerges is that the magneto-ionic environments of radio galaxies are significantly more complicated than was apparent from earlier work. The unique feature of this thesis is that the target radio galaxies are all large and highly polarized, enabling the determination of Faraday rotation and depolarization at a large number of independent points with high signalto-noise ratio. This in turn allows global variations across the sources to be determined, as well as accurate estimates of spatial statistics. In Section 6.5, I summarize the main results obtained in Chapters 4, 5 and 6. The general conclusions are given in Sec. 6.6 as a set of answers to the questions posed in the Abstract and finally Sec. 6.7 briefly lists some topics for further work. 6.5 Summary 6.5.1 The tailed source 3C 449 The RM and depolarization across the source both appear to be consistent with a pure, mostly resolved foreground Faraday screen. The RM structure shows no preferred direction anywhere in the radio source. This is consistent with an isotropic, turbulent magnetic field fluctuating over a wide range of spatial scales. I quantified the statistics of the magnetic-field fluctuations by deriving RM structure functions, which have been fitted using models derived from theoretical power spectra. The errors due to undersampling have been estimated by making multiple twodimensional realizations of the best-fitting power spectrum. Depolarization measurements have also been used to estimate the minimum scale of the magnetic field variations. I then developed three-dimensional models with a gas density distribution derived from X-ray observations and 125
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Alma Mater Studiorum Università de
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To Hypatia from Alexandria in Egypt
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Contents Abstract i 1 Physics of ra
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4.6.3 The outer scale of the magnet
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Abstract The existence of diffuse m
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2. Two-dimensional Monte Carlo simu
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Chapter 1 Physics of radio galaxies
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1.2. Non-thermal emission mechanism
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1.2. Non-thermal emission mechanism
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1.3. Radio galaxies 7 FR II sources
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1.3. Radio galaxies 9 (a) (b) Figur
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1.3. Radio galaxies 11 pressure, th
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Chapter 2 The X-ray environment of
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2.2. The thermal component 15 Figur
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2.3. Radio source - environment int
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2.3. Radio source - environment int
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Chapter 3 Magnetic fields in the ho
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3.1. Introduction 23 Figure 3.1: Ex
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3.1. Introduction 25 to the relativ
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3.2. Faraday Rotation 27 The RM can
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3.2. Faraday Rotation 29 Figure 3.4
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3.3. Depolarization 31 3.3 Depolari
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3.5. The magnetic field profile 33
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3.6. Tangled magnetic field 35 rad
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3.7. The magnetic field power spect
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Chapter 4 Structure of the magneto-
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4.1. The radio source 3C 449: gener
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4.3. The Faraday rotation in 3C 449
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4.3. The Faraday rotation in 3C 449
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4.4. Depolarization 51 Figure 4.4:
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4.4. Depolarization 53 1.25 arcsec
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4.5. Two dimensional analysis 55 sm
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4.5. Two dimensional analysis 57 Fi
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4.6. Three-dimensional analysis 59
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4.7. Summary and comparison with ot
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Page 89 and 90: Chapter 5 Ordered magnetic fields a
Page 91 and 92: 5.1. The Sample 75 35 49 00 ROSAT P
Page 93 and 94: 5.1. The Sample 77 5.1.1 0206+35 02
Page 95 and 96: 5.2. Analysis of RM and depolarizat
Page 97 and 98: 5.3. Rotation measure images 81 IMA
Page 99 and 100: 5.3. Rotation measure images 83 cor
Page 101 and 102: 5.4. Depolarization 85 Therefore, a
Page 103 and 104: 5.5. Rotation measure structure fun
Page 105 and 106: 5.6. Rotation-measure bands from co
Page 111 and 112: 5.7. Rotation-measure bands from a
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Page 115 and 116: 5.8. Discussion 99 5.8 Discussion 5
Page 117 and 118: 5.8. Discussion 101 line−of−sig
Page 119 and 120: 5.8. Discussion 103 flat slopes. I
Page 121 and 122: 5.9. Conclusions and outstanding qu
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Page 125 and 126: Chapter 6 Faraday rotation in two e
Page 127 and 128: 6.2. Two-dimensional analysis: rota
Page 135 and 136: 6.3. Two-dimensional analysis: stru
Page 137 and 138: 6.4. Preliminary conclusions 121 Ta
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Page 143 and 144: 6.5. Summary 127 responsible for th
Page 145 and 146: 6.6. General conclusions 129 radio
Page 147 and 148: 6.7. Future prospects 131 and is th
Page 149: Appendix 133
Page 152 and 153: 136 Data reduction and imaging of l
Page 160 and 161: 144 BIBLIOGRAPHY Bîrzan, L., Raffe
Page 162 and 163: 146 BIBLIOGRAPHY Ensslin, T.A. & Go
Page 164 and 165: 148 BIBLIOGRAPHY Jeltema, T.E. & Pr
Page 166 and 167: 150 BIBLIOGRAPHY Owen, F.N., 1989,
Page 168 and 169: 152 BIBLIOGRAPHY 152
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Alma Mater Studiorum Universit`a degli Studi di Bologna ... - Inaf

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