Table Of ContentThe Physics of Non-Thermal Radio Sources
NATO ADVANCED STUDY INSTITUTES SERIES
Proceedings of the Advanced Study Institute Programme, which aims
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Series C - Mathematical and Physical Sciences
Volume 28 - The Physics of Non-Thermal Radio Sources
The Physics of
Non-Thermal Radio Sources
Proceedings of the NATO Advanced Study Institute
held in Urbino, Italy, June 29-July 13, 1975
edited by
GIANCARLO SETTI
University of Bologna, Laboratorio di Radioastronomia CNR,
Via Irnerio 46, 40126 Bologna, Italy
D. Reidel Publishing Company
Dordrecht-Holland / Boston-U.S.A.
Published in cooperation with NATO Scientific Affairs Division
ISBN-13: 978-94-010-1519-6 e-ISBN-13: 978-94-010-1517-2
001: 10.1007/978-94-010-1517-2
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Copyright © 1976 by D. Reidel Publishing Company, Dordrecht, Holland
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CONTENTS
FOREWORD VII
G. Miley 1
MORPHOLOGY OF EXTRAGALACTIC RADIO SOURCES
K.I. Kellermann 27
COMPACT RADIO SOURCES IN QUASARS AND GALACTIC NUCLEI
E.M. Burbidge 41
THE OPTICAL PROPERTIES OF RADIO GALAXIES
P.A. Strittmatter 55
OPTICAL STUDIES OF QUASARS AND BL LAC OBJECTS
W.L.W. Sargent 67
RADIO SOURCES AND CLUSTERS OF GALAXIES
R.D. Ekers 83
THE RADIO LUMINOSITY FUNCTION OF GALAXIES
P.A.G. Scheuer 93
MODELS OF EXTRAGALACTIC RADIO SOURCES
M.J. Rees 107
BEAM MODELS FOR DOUBLE SOURCES AND THE NATURE OF THE PRIMARY
ENERGY SOURCE
G.R. Burbidge 121
SOME PROBLEMS ASSOCIATED WITH NON-THERMAL RADIO SOURCES
L. Wo1tjer 131
ENERGETICS OF QUASARS AND RADIO GALAXIES
E.N. Parker 137
THE ACCELERATION OF PARTICLES TO HIGH ENERGY
VI CONTENTS
E.N. Parker 169
THE BASIC PHYSICAL PROPERTIES OF A GALACTIC MAGNETIC FIELD
F. Pacini 179
PULSARS
L. Wo1tjer 197
SUPERNOVA REMNANTS
R.M. Hje11ming 203
RADIO STARS
R. Giacconi 229
X-RAY OBSERVATIONS
SUBJECT INDEX 271
POREHORD
This volume contains a series of lectures presented at the 3rd
Course of the International School of Astrophysics held in Urbino,
Italy from June 29 - July 13, 1975 under the auspices of the
"E. Majorana" Centre for Scientific Culture. The course was jointly
planned by L. Woltjer and myself and was fully supported by a grant
from the NATO Advanced Study Institute Programme. It was organized
with the aim of providing students and young researchers with an
up-to-date account on the subject of the structure, origin, and
evolution of non-thermal radio sources and was attended by 88
participants from 15 countries.
It is well known that radio astronomical research has played
a fundamental role in the development of modern astrophysics and
cosmology, leading in particular to the exciting discoveries of
new and unsuspected classes of objects such as radio galaxies, qua
sars and pulsars. However, it is probably fair to say that we are
still far from a complete understanding of the physics of non
thermal radio sources except for the fact that, in general, the
radio emission is adequately explained in terms of the "synchro
tron" mechanism.
In the case of extragalactic sources, we know that the very
large amounts of energy observed are supplied as a consequence
of violent activity taking place in galactic nuclei. Yet we are
still faced with a number of unsolved problems, for example: what
is the nature of the ultimate source of this energy, how and where
is the energy so efficiently converted into relativistic particles,
and how is the energy collimated to millions of light years away
with such a high degree of symmetry, as found in the double radio
sources.
Phenomena observed in extragalactic sources reoccur with
striking similarities in galactic non-thermal radio sources, though,
of course, on different space and time scales. For instance, the
radio properties of some X-ray stars like Sco X-I and Cyg X-3 are
typical of the phenomenology found in quasars. Moreover, the dis
covery of the association between supernova remnants and pulsars
has triggered the notion that very efficient particle acceleration
can be obtained by rotating magnetic objects.
On the observational side, a big step forward has been obtained
VIII FOREWORD
by the completion of large aperture synthesis radio telescopes,
which have permitted a detailed mapping of radio sources, and by
the development of very long base-line interferometry (VLBI), with
resolutions down to 10-3 - 10-4 arc sec, which for the first time
has rendered possible radio investigations of the structures of the
very compact radio sources found in galactic nuclei and quasars.
The observations obtained with this new instrumentation, combined
with the work in the optical, infrared and X-ray domain, have made
great strides in recent years toward improved testing of radio
source models.
We feel that the material presented at the Institute represents
a rather complete and comprehensive coverage of the present status
of studies of non-thermal radio sources, though one is aware of
rapid developments in this field of research. The various aspects
of this exciting subject were covered in a series of lectures, pre
sented in this volume, totaling 44 hours and in 14 topical seminars
given by the participants.
I wish to express my gratitude to the Scientific Affairs Divi
sion of the North Atlantic Treaty Organization for the generous
support given to the course. Sincere thanks are also due to Mr.
L. Baldeschi for helping with the organization of the meeting and
for drawing a number of figures contained in this volume; to Mrs.
B. Mandel for the patient typing and help in the editing; and to
Mr. R. Primavera for the photographic reproduction of part of the
figures.
A special thanks is, of course, due to all the lectures and
participants who contributed so much to the success of the course
and provided. the articles for this volume.
Finally, I wish to express my sincere gratitude to L. Woltjer
for his fine collaboration as co-director of the course.
Prof. Giancarlo Setti
University of Bologna
Laboratorio di Radio-
astronomia CNR
Via Irnerio 46
40126 Bologna, Italy
MORPHOLOGY OF EXTRAGALACTIC RADIO SOURCES
George Miley
Sterrewacht, Huygens Laboratorium
Leiden, The Netherlands
1. TECHNIQUES FOR MEASURING MORPHOLOGY
"The astronomical instruments have been in use from very ancient
days, handed down from one dynasty to another, and closely guard
ed by the official astronomers. Scholars have therefore had little
opportunity to examine them, and this is the reason why unorthodox
cosmological theories were able to spread and flourish." - Fang,
Hsuan-Ling, History of the Chin Dtnasty, 635 AD.
This section is intended to be a bluffers guide' for readers of
morphology papers.
1.1 Some peripheral techniques
a. Single dish
Resolution AS ~ Air (for r = 100m (Bonn dish)
at A - 3 em, AS ~ 1'). Only useful for
largest sources at short wavelength. Obser
vations seriously limited by receiver sta
bility.
b. Luna~ occultations
Variation of source flux density as it is occulted by moon gives
one-dimensional brightness distribution convolved with diffraction
pattern of moon. For restoration procedure see Scheuer (1962),
von Hoerner (1964). AS depends on signal to noise of source.
AS ~ 1" readily achievable.
G. Setti (ed.). The PhyllicB ofN on-Thermtll RJldio SourceB, 1-26. AU RightB ReBe11led.
Copyright e 1976 by D. Reidel PubliBhing Company, Dordrecht-Holiand.
2 GEORGE MILEY
Advantages : Resolution not highly dependent on frequency.
Disadvantages: Two-dimensional structure difficult to reconstruct.
Can only be applied to sources that happen to lie on moon's path
(i.e. - 29° < 0 < + 29°).
First suggested by Getmansev and Ginzbury (1950). Most notable
success in pinpointing 3C 273 (Hazard et al. 1963) led directly
to discovery of quasars. Recently several hundred weak sources
have been studied with a new telescope in India specially designed
for occultation work, e.g. Kapahi et al. (1974).
c. Interplanetary scintillations
Irregularities in electron density of solar corona (scale ~ 100
km) cause small sources to flicker or "scintillate". Large sources
are unaffected - frosted glass effect. Degree of scintillation
and its variation with distance from Sun can give useful informa
tion on amount of small scale « I") structure in a source. First
reported by Hewish et al. (1964). See Cohen et al. (1967), Little
and Hewish (1968).
Advantages : Easy. High resolution at low frequency.
Disadvantages: All but crudest inferences about structure depend
on assumed model for solar corona. Can only be applied to limited
source list (~ 50° from Sun).
1.2 Interferometry and aperture synthesis
This is much the most important tool used by morphologians. It
was first developed by Ryle (1952) and independently by Christiansen
(1953) and Mills and Little (1953). An excellent account is given
by Fomalont and Wright (1974). Here we shall summarize some of
the most important points stressing the jargon which is often
used by morphologians in their articles
//~
Analogue of Young's //8"\ Bp~
double slit experiment.
/ /
Gives roughly same ,~// //
resolution as single dish / V2=V02 cos[wt+(BcosBIl / v,'
BX
stretching between two
telescopes.
