Structure in Radio Galaxies

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The original document from which this microfiche has been prepared has these imperfectionsr ) } missing pages/figures numbered: \ | wrong pagination I 1 poor overall printing quality | 1 combinations of the above INIS Clearinghouse other; Text has been cut during IAEA. Microfiching preparation» on P. 0. Box 100 left side. A-1400, Vienna, Austria I - * • • A k STRUCTURE IN RADIO GALAXIES •£f STRUCTURE IN RADIO GALAXIES Proefschrift ter verkrijging van de graad van Doctor in de Wiskunde en Natuurwetenschappen aan de Rijksuniversiteit te Leiden, op gezag van de Rector Magnificus Dr.A.A.H.Kassenaar hoogleraar in de Faculteit der Geneeskunde, volgens besluit van het College van Decanen te verdedigen op woensdag 1 Oktober 1980 te klokke 14.15 uur door WILLEM JOHANNES MARIA VAN BREUGEL geboren te Oisterwijk in 1948 Sterrewacht Leiden kripsrepromeppel Promotor : Prof. Dr. H. van der Laan Co-promotor: Dr. G.K. Miley Referent : Dr. A.G. Willis m i>> : Aan Imke Cover: The projected magnetic field distribution of the extra- galaatio radio source 3C 310 superimposed on a radio photo of the total intensity at 6 am as observed with the Westerbork Synthesis Radio Telescope The research reported in this dissertation was supported financially by the Netherlands Organization for the Advanaement of Pure Research (Z.W.O.). The Westerbork Radio Observatory and the Reduction Group are administered by the Netherlands Foundation for Radio Astronomy (S.R.Z.M.) which is also supported financially by Z.W.O. CONTENTS page nrs. Chapter I Introduction 9 Table of observed sources 14 Chapter II Radio "Jets" 15 W.J.M. van Breugel and G.K. Miley, 1977 Nature 265_, 315 Chapter III Optical Observations of Radio Jets 18 Harvey R. Butcher, Wit van Breugel and George K. Miley, 1980, Astroph. J. 236_, 749 1. Introduction 18 2. Observations 18 3. Results 19 4. Discussion 21 Appendix to Chapter III 28 Chapter IV Multifrequency Observations of Extended Radio Galaxies I: 3C 310 31 Published in Astron. Astrophys. IU_, 265 (1980) 1. Introduction 31 2. Observations and Reductions 31 3. Intensity Data 32 4. Polarization Data 33 5. Spectral Comparison 1.4 GHz/5 GHz (Intensity) 34 6. Spectral Comparison 1.4 GHz/5 GHz (Polarization) 35 7. Discussion 37 8. Conclusions 39 Chapter V Multifrequency Observations of Extended Radio Galaxies II: B 0844+31 41 Published in Astron. Astrophys. 81_, 275 (1980) 1. Introduction 41 2. Observations 41 $*: 3. Spectral Comparison 43 4. Physical Parameters 45 5. Discussion 45 1 6. Conclusions 46 '•', ?. page nrs. Chapter VI Multifrequency Observations of Extended Radio Galaxies III: 3C 465 48 Astron. Astrophys. (in press) 1. Introduction 49 2. Observations 50 3. Spectral Comparison 5] 4. Further Analysis of the Polarization Data 53 5. Magnetic Field Distribution 57 6. Physical Parameters 57 7. Discussion 59 8. Conclusions 65 Chapter VII Multifrequency Observations of Extended Radio Galaxies IV: The Large Radio Jet Galaxy 4CT 74.17.1 82 W.J.M. van Breugel and A.G. Willis, Astron. Astrophys. (submitted) 1. Introduction 83 2. Observations 83 3. Radio Data. 84 4. Interfrec 'en.cy Comparison 87 5. Optical Data 9] 6. Discussion 92 7. Conclusions 97 Chapter VIII Multifreqaency Observations of Extended Radio Galaxies V: 3C 31, 3C 33.1, 3C 35, 3C 66B, 3C 129, 3C 130, 3C 223, 3C 310, 3C 390.3, 4C 48.29. 114 1. Introduction 114 2. Observations j]5 3. Maps 116 4. Notes on the Sources 117 I I 35 page nrs. Chapter IX Multifrequency Comparison of the Total Intensity and n Polarization Data for: 3C 31, 3C 5, 3C 66B, 3C 129. 16] 1. Introduction 162 2. 3C 31 166 3. 3C 35 169 A. 3C 66B 176 5. 3C 129 184 6. Discussion and Conclusions 195 • Chapter X VLBI Observations of a mixed Selection of Extra Galactic Objects 200 W.J.M. van Breugel, R.T. Sahilizzi, E. Hummel, V.K. Kapahi, Astr-on. Astropkys. (in press) 1. Introduction 201 2. Observations 201 3. Results and Discussion 202 Chapter XI Concluding Summary 210 Samenvatting 213 Studie-overzicht 217 i I CHAPTER I Introduction During the past two decades aperture synthesis radio telescopes have revealed the structure in strong, extragalactic radio sources associated with galaxies with increasingly high resolution and sensitivity. A study at several radio wavelengths of the total and polarized intensity structure of a sample of such "radio galaxies" forms the major part of this thesis. A morphological characteristic of radio galaxies is that they are often quite symmetric, with two radio "lobes" straddling an associated (optical) galaxy. Often a compact radio component ("radio core") is found to coincide with the nucleus of the galaxy. The characteristics of radio galaxies have naturally led to the idea that the radio sources originate in the galactic nuclei with which they are associated. Since the radio emission is partially polarized it was suggested (Ginzburg 1951; Shklovskii 1952, 1953) that this radiation was of non-thermal origin, caused by charged particles moving at relativistic speed in a magnetic field. Because such radiation was first observed in synchrotron accelerators it is called "synchrotron radiation". Using the theory of synchrotron radiation to- gether with many, plausible, assumptions about the astrophysical circumstances prevailing in radio galaxies it became clear that the amount of energy required to power a radio galaxy is enormous. Since no general steepening of the radio spectrum (^ 10 Hz - 10 Hz) has been found for the radio lobes at high fre- quencies (the radio cores constitute a different class), it also became evident that compensating for the radiative energy losses at a nearly constant level over a long period of time is necessary. Contrary to what was previously be- lieved, the radiating nonthermal plasma could not have been formed in a single event after which its further evolution is determined solely by radiative and expansion losses. During its lifetime some replenishment or reacceleration of the relativistic particles is required. It was therefore proposed that radio •/> galaxies are powered by their parent galaxies (quasi) continuously (e.g. van der '-ig; Laan and Perola, 1969) and various models were conceived to do this in the most -#£ efficient way. Two of the most important models are the recurrent form of the ^ "plasmon" ejection model (de Young and Axford 1967; Christiansen et al. 1977) ^jj and the "beam" model (Rees, 1971; see Blandford and Rees 1978 for later ver- fS sions). In the first model plasmons (blobs containing thermal plasma, relativistic particles and magnetic fields) are assumed to be shot out intermittently from a galactic nucleus and, to avoid severe adiabatic expansion losses, are supposed to be confined by rampressure of an external, intergalactic gas. Such models have been applied, for example, to radio galaxies with a head-tail morphology suggestive of the motion of the parent galaxy through such an ambient intergalactic gas (Miley et al., 1972; Jaffe and Perola, 1973). In the original version of the beam model it was not suspected that the energy transport would be visible at radio wavelengths. However strong observa- tional evidence for the existence of energy beams was provided by the discovery of radio "jets" extending between the galactic nuclei and the radio lobes. In current versions of the beam model it is assumed that the energy is transported in a directed flow containing bulk matter, including relativistic particles and magnetic fields. A jet presumably delineates the path along which most of the energy is transported and the strength of the jet may well be inversely corre- lated with the efficiency of the energy transport. Due to the increasing resolution and sensitivity of aperture synthesis radio telescopes over the past few years, radio jets have been ODServed in many radio galaxies. With the exception of the strong double source 3C 219 (Turland, 1975), initially radio jets were found only in the less powerful radio galaxies with complex morphologies.

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