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138 Data reduction and imaging of lobed radio galaxies Table 6: Resolutions and noise levels for the images used in this work. Col.1 source name; Col.2 angular resolution; Col.3 observing frequency; Col.4 VLA configurations; Col.5 imaging method; Col.6 off-source noise level on the I image (σ I ) and the average of the noise levels for Q and U (σ P ). Col.7 approximate maximum scale of structure imaged reliably (Ulvestad, Perley & Chandler 2009). Col.8 corrected single-dish flux densities put in the standard scale of Baars et al. (1977), as used at the VLA. Col.9 references. Source FWHM Freq Config. Method rms noise level Max I int /Jy Ref. [arcsec] [GHz] I QU [µJy beam −1 ] scale Image SD σ I σ P [arcsec] 0206+35 1.20 4860.1 BC MR MR 12 12 300 0.90±0.02 0.98±0.12 1 1.20 1464.9 AB MR MR 21 22 300 2.12±0.04 2.13 3 1.20 1385.1 AB MR MR 21 23 300 2.12±0.04 2.22 3 1.20 1425.0 AB MR − 19 − 300 2.12±0.04 2.18 4 4.50 4860.1 BC MR − 18 − 300 0.90±0.02 0.98±0.12 1 4.50 1425.0 AB MR − 38 − 300 2.13±0.04 2.18 4 0755+37 1.30 4860.1 BCD MR MR 7.8 7.9 300 1.26±0.03 1.27±0.02 2 1.30 1464.9 ABC MR MR 28 28 300 2.60±0.05 2.53±0.09 2 1.30 1385.1 ABC MR MR 27 26 300 2.74±0.05 2.62±0.09 2 1.30 1425.0 ABC MR − 20 − 300 2.64±0.05 2.57±0.09 2 4.00 4860.1 BCD MR MR 14 12 300 1.25±0.03 1.27±0.02 2 4.00 1464.9 ABC MR MR 44 42 300 2.59±0.05 2.53±0.09 2 4.00 1385.1 ABC MR MR 46 36 300 2.73±0.05 2.62±0.09 2 4.00 1425.0 ABC MR MR 32 − 300 2.65±0.05 2.57±0.09 2 M 84 1.65 4860.1 a ABC MR MR 15 11 300 2.94±0.06 2.88±0.08 3 1.65 1413.0 AB MR MR 140 140 120 6.03±0.12 6.44±0.24 3 4.5 4860.1 a C MR MR 23 20 300 2.98±0.06 2.88±0.08 3 4.5 1464.9 B MR MR 120 70 120 6.14±0.12 6.32±0.24 3 4.5 1413.0 AB MR MR 210 150 120 5.99±0.12 6.44±0.24 3 4.5 1385.1 B MR MR 130 69 120 6.46±0.13 6.51±0.24 3 References: 1 Gregory & Condon (1991); 2 Kühr et al. (1981); 3 Laing & Peacock (1981); 4 White & Becker (1992). a Although the 1980 and 1981 observations have a centre frequency of 4885.1 MHz, the weighted mean for the combined dataset is still close to 4860.1 MHz. flux densities using the AIPS verbTVSTAT. We estimate that the errors are dominated by a residual scale error of≈2%. All of the results are in excellent agreement with single-dish measurements (Table 6). The configurations, resolutions, deconvolution algorithms and noise levels for the final images are listed in Table 6. The noise levels were measured before correction for the primary beam, and are appropriate for the centre of the field. .2 Images Our conventions are as follows: 1. images of total intensity are show as grey-scales, over a range indicated by the labelled wedges. 138
.2. Images 139 2 4 6 2 4 6 8 10 35 48 30 (g) 15 DECLINATION (J2000) 00 47 45 30 15 00 02 09 43 42 41 40 39 38 37 36 35 34 RIGHT ASCENSION (J2000) p = 1 02 09 43 42 41 40 39 38 37 36 35 34 RIGHT ASCENSION (J2000) Figure 11: 0206+35 at 4.9 GHz with angular resolution of 1.2 arcsec FWHM. Left: total intensity distribution I in mJy (beam area) −1 . Right: apparent B a vectors with lengths proportional to p 4.9 derived from the 3-frequency RM fit, superimposed on a false-colour display of I. 2. We also show intensity gradient for 0755+37 and M 84,|∇I|, derived using a Sobel filter (Sobel & Feldman, 1968). 3. Linear polarization is illustrated by plots in which vectors have lengths proportional to the degree of polarization at 4.9 GHz (p 4.9 ) and directions along the apparent magnetic field (B a ). They are superposed on false-colour images of either I (again with a labelled wedge indicating the range) or|∇I|. B a ) vectors are plotted where I ≥ 5σ I . A value of p = 1 is indicated by the labelled bar. The apparent field direction isχ 0 +π/2, where χ 0 is the E-vector position angle corrected to zero-wavelength by fitting to the relation χ(λ 2 )=χ 0 + RMλ 2 for foreground Faraday rotation. In some sources, we used the RM images at lower resolution to correct the position angles. This procedure is valid if the RM varies smoothly over the low-resolution image, and maximises the area over which we can determine the direction of the apparent field. 4. The restoring beam is shown in the bottom left-hand corner of each plot. 5. We refer to parts of the sources by the abbreviations N, S, E, W (for North, South, East, West) etc. 6. We refer to the main (brighter) and counter (fainter) jets. 139
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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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Chapter 5 Ordered magnetic fields a
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5.1. The Sample 75 35 49 00 ROSAT P
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5.1. The Sample 77 5.1.1 0206+35 02
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5.2. Analysis of RM and depolarizat
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5.3. Rotation measure images 81 IMA
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5.3. Rotation measure images 83 cor
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5.4. Depolarization 85 Therefore, 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 137 and 138: 6.4. Preliminary conclusions 121 Ta
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Page 141 and 142: Summary and conclusions The goal of
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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