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

More documents

Recommendations

Info

74 5. Ordered magnetic fields around radio galaxies of galaxies. The RM images of radio galaxies presented in this Chapter show clearly anisotropic “banded” patterns over part or all of their areas. In some sources, these banded patterns coexist with regions of isotropic random variations. The magnetic field responsible for these RM patterns must, therefore, have a preferred direction. One source whose RM structure is dominated by bands is already known: M 84 (Laing & Bridle 1987). In addition, there is some evidence for RM bands in sources which also show strong irregular fluctuations, such as Cygnus A (Carilli & Taylor 2002). It is possible, however, that some of the claimed bands could be due to imperfect sampling of an isotropic RM distribution with large-scale power, and I return to this question in Section 5.8.1. In this Chapter I present new RM images of three sources which show spectacular banded structures, together with improved data for M 84. The environments of all four sources are well characterized by modern X-ray observations, and I give the first comprehensive description of the banded RM phenomenon. I present an initial attempt to interpret the phenomenon as a consequence of source-environment interactions and to understand the difference between it and the more usual irregular RM structure. The RM images reported are derived from new or previously unpublished archive Very Large Array data for the nearby radio galaxies 0206+35, M 84 (Laing et al. in preparation), 3C 270 (Laing, Guidetti & Bridle in preparation) and 3C 353 (Swain, private communication; see Swain 1996). 5.1 The Sample High quality radio and X-ray data are available for all of the sources. In this Section I summarize those of their observational properties which are relevant to this RM study. A list of the sources and their general parameters is given in Table 5.1, while Table 5.2 shows the X-ray parameters taken from the literature and equipartition parameters derived from radio observations in this work. The sources were observed with the VLA at several frequencies, in full polarization mode and with multiple configurations so that the radio structure is well sampled. The VLA observations, data reduction and detailed descriptions of the radio structures are given for 0206+35 and M 84 by Laing, Guidetti et al. (in preparation), for 3C 270 by Laing, Guidetti & Bridle (in preparation), and for 3C 353 by Swain (1996). All of the radio maps show a core, two sided jets and a doublelobed structure with sharp brightness gradients at the leading edges of both lobes. The synchrotron minimum pressures are all significantly lower than the thermal pressures of the external medium (Table 5.2). All of the sources have been observed in the soft X-ray band by more than one satellite, 74
5.1. The Sample 75 35 49 00 ROSAT PSPC 12 38 00 Chandra 35 48 30 DECLINATION (J2000) 35 48 00 35 47 30 DECLINATION (J2000) 12 37 00 12 36 00 35 47 00 (a) 12 35 00 (b) 02 09 44 02 09 40 02 09 36 RIGHT ASCENSION (J2000) 02 09 32 12 27 45 12 27 40 12 27 35 RIGHT ASCENSION (J2000) 12 27 30 05 52 00 XMM−Newton ;00 56 00 XMM−Newton DECLINATION (J2000) 05 50 00 05 48 00 DECLINATION (J2000) ;00 57 00 ;00 58 00 ;00 59 00 05 46 00 12 19 40 12 19 30 12 19 20 RIGHT ASCENSION (J2000) 12 19 10 (c) ;01 00 00 ;01 01 00 17 20 40 17 20 30 RIGHT ASCENSION (J2000) 17 20 20 (d) Figure 5.1: X-ray images overlaid with radio contours for all sources: (a) 0206+35: 1385.1 MHz VLA radio map with 1.2 arcsec FWHM; the contours are spaced by factor of 2 between 0.06 and 15 mJy beam −1 . The ROSAT PSPC image (Worrall & Birkinshaw 2000), is smoothed with a Gaussian ofσ=30 arcsec. (b) M 84: 1413.0 MHz VLA radio map with 4.5 arcsec FWHM; the contours are spaced by factor of 2 between 1 and 128 mJy beam −1 . The Chandra (Finoguenov & Jones 2001) image is a wavelet reconstruction on angular scales from 4 up to 32 arcsec. (c) 3C 270: 1365.0 MHz VLA radio map with 5.0 arcsec FWHM; the contours are spaced by factor of 2 between 0.45 and 58 mJy beam −1 . The XMM-Newton image (Croston, Hardcastle & Birkinshaw 2005) is smoothed with a Gaussian ofσ=26 arcsec. (d) 3C 353: 1385.0 MHz VLA radio map with 1.3 arcsec FWHM; the contours are spaced by factor of 2 between 0.35 and 22 mJy beam −1 . The XMM-Newton image (Goodger et al. 2008) is smoothed with a Gaussian ofσ=30 arcsec. The Chandra image of 3C 270 is displayed in logarithmic scale. 75
Page 1:
Alma Mater Studiorum Università de
Page 5:
To Hypatia from Alexandria in Egypt
Page 9 and 10:
Contents Abstract i 1 Physics of ra
Page 11 and 12:
4.6.3 The outer scale of the magnet
Page 13 and 14:
Abstract The existence of diffuse m
Page 15 and 16:
2. Two-dimensional Monte Carlo simu
Page 17 and 18:
Chapter 1 Physics of radio galaxies
Page 19 and 20:
1.2. Non-thermal emission mechanism
Page 21 and 22:
1.2. Non-thermal emission mechanism
Page 23 and 24:
1.3. Radio galaxies 7 FR II sources
Page 25 and 26:
1.3. Radio galaxies 9 (a) (b) Figur
Page 27 and 28:
1.3. Radio galaxies 11 pressure, th
Page 29 and 30:
Chapter 2 The X-ray environment of
Page 31 and 32:
2.2. The thermal component 15 Figur
Page 33 and 34:
2.3. Radio source - environment int
Page 35 and 36:
2.3. Radio source - environment int
Page 37 and 38:
Chapter 3 Magnetic fields in the ho
Page 39 and 40: 3.1. Introduction 23 Figure 3.1: Ex
Page 41 and 42: 3.1. Introduction 25 to the relativ
Page 43 and 44: 3.2. Faraday Rotation 27 The RM can
Page 45 and 46: 3.2. Faraday Rotation 29 Figure 3.4
Page 47 and 48: 3.3. Depolarization 31 3.3 Depolari
Page 49 and 50: 3.5. The magnetic field profile 33
Page 51 and 52: 3.6. Tangled magnetic field 35 rad
Page 53 and 54: 3.7. The magnetic field power spect
Page 59 and 60: Chapter 4 Structure of the magneto-
Page 61 and 62: 4.1. The radio source 3C 449: gener
Page 63 and 64: 4.3. The Faraday rotation in 3C 449
Page 65 and 66: 4.3. The Faraday rotation in 3C 449
Page 67 and 68: 4.4. Depolarization 51 Figure 4.4:
Page 69 and 70: 4.4. Depolarization 53 1.25 arcsec
Page 71 and 72: 4.5. Two dimensional analysis 55 sm
Page 73 and 74: 4.5. Two dimensional analysis 57 Fi
Page 75 and 76: 4.6. Three-dimensional analysis 59
Page 83 and 84: 4.7. Summary and comparison with ot
Page 89: Chapter 5 Ordered magnetic fields a
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
Page 113 and 114: 5.7. Rotation-measure bands from a
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
Page 123 and 124: 5.9. Conclusions and outstanding qu
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
Page 139 and 140: 6.4. Preliminary conclusions 123
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 154 and 155:
Page 156 and 157:
Page 158 and 159:
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
show all

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

Create successful ePaper yourself

Delete template?

Save as template?