Galactic High-Energy Astrophysics High-Accuracy Timing and Positional Astronomy: Lectures Held at the Astrophysics School IV Organized by the European Astrophysics Doctoral Network (EADN) in Graz, Austria, 19–31 August 1991

295 Pages·1993·4.16 MB·English

by  A. Achterberg (auth.)

J. van Paradijs H. M. Maitzen (Eds.)
Galactic High-Energy
Astrophysics
High-Accuracy Timing
and Positional Astronomy
LecturesH eld at the
Astrophysics School IV
Organized by the EuropeanA strophysics Doctoral Network
(EADN) in Graz, Austria, 19-31 August 1991
Springer-Verlag
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Editors
Jan van Paradijs
Astronomical Institute “Anton Pannekoek” and
Center for High-Energy Astrophysics
Kruislaan 403, NL-1098 SJA msterdam, The Netherlands
Hans Michael Maitzen
Institut fur Astronomie der Universitat Wien
Ttirkenschanzstral3e 17, A- 1180 Wien, Austria
ISBN 3-540-56874-3 Springer-Verlag Berlin Heidelberg New York
ISBN O-387-56874-3 Springer-Verlag New York Berlin Heidelberg
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PREFACE
The 4th Predoctoral Astrophysics School of the European Astrophysics Doctoral Network (EADN)
was held from August 19 - 31, 1991 at Graz-Marialrost with the participation of 7 teachers, and 34
students from 11 European countries. With this School EADN has completehda lf a decade of
European collaboration in the field of academic teaching in astrophysics. After the EADN Schools at
Les Houches (France, 1988), Ponte de Lima (Portugal, 1989) and Dublin (Ireland, 1990) Austrian
astronomy hosted the fourth School and chose Graz as its venue.
Graz is related to both subjects of the School - Galactic High-Energy Astrophysics, and High
Accuracy Timing and Positional Astronomy - through historical and contemporary circumstances. It
is known as one of the Kepler cities. In 1994 Graz will celebrate the 400th anniversary of Kepler's
arrival there where he started both his teaching and scientificca reers. Keplewro rked on the most
accurate and numerous positional observations available att hat time through the efforts of Tycho
Brahe; he can be said to have also contributed to thef ield of HighE nergy Astronomy by his book on
the detection of a STELLA NOVA; which in fact was the last naked-eye supernovad iscovery (1604)
before the recent famous supernova SN 1987A.
We would like to mention here alsot hat the discoverer of cosmic rays - part of the fast topic of the
Graz School - was the Nobel Prize winner Viktor F. Hess who conducted his research at the
Karl-Franzens University of Graz. Other wen-known scientists, who at somet ime in their careers
worked at this University, include Boltzmann, Schr6dinger (Nobel Prize 1933) and Mach.
Like the other two classical Austrian universities of Vienna and Innsbmck the Karl-Franzens
University has an Institute for Astronomy. We would like to express our deep gratitude to this
institute, especially to its head Prof. Dr. Hermann Haupt and two of his students, Karin Muglach and
Robert Greirnel, for their support during the preparatory phase and the School weeks.
We acknowledge with grateful appreciation financial support for the School from:
SCIENCE, the scientific stimulation programme of the Commission of the European Community;
- the Austrian Ministry of Science and Research;
- the Government of the Land Steiermark (Styria);
- - the City of Graz, in addition to a truly delightful reception by its mayor Alfred Stingl and City
Counsellor Helmut Strobl;
the Granholm Foundation (Sweden), and
- the Oesterreichiscbe Forschungsgemeinschaft.
-
Extensive cooperation and help came from the home institute of the Local Organizer, the Vienna
Institut f'tir Astronomic (head Prof. Dr. Paul Jackson), and especially from its collaborators Dr.
Anneliese Schnell, Dr. Ernst Goebel and Mag. Franz Kerschbaum.
Thanks go also to the staff of the Bildungshaus Mariatrost whichp rovided not only dormitories and
meeting rooms, but also a relaxed and friendly atmosphere surrounded by magnificent natural beauty.
Last but not least, we wish to specially thank the Coordinator of EADN, Prof. Dr. Jean Heyvaerts
who completed with his participation in the Graz School a period of five years at the helm of EADN.
The 4th EADN School in Graz was pronounced successful by teachers and students alike. It occurred
at a very critical pointi n recent European history, since its beginning coincided with the coup d'etaitn
the former Soviet Union. Together with the scientific educational values and the charming Graz
downtown atmosphere this may have contributed to a very special feeling of togetherness of young
European doctoral students in astrophysics during those two weeks in August 1991.
Amsterdam/Vienna, October 1992
J. van Paradijs, H.M. Maitzen
Contents
Part I Galactic High-Energy Astrophysics
A. Achterberg
Particle Acceleration in Astrophysics ............................. 3
1. Introduction ............................................... 3
2. Particle Acceleration: General Principles ...................... 4
2.1 Stochastic and Regular Fermi Acceleration .................. 4
2.2 The Spectrum due to Stochastic Fermi Acceleration ........... 8
2.3 Stochastic Acceleration by Plasma Waves and Turbulence ...... 9
2.4 "Fermi Deceleration": Expansion Losses .................... 15
2.5 The Energy Balance in Stochastic Fermi Acceleration ......... 16
3. Particle Acceleration near Astrophysical Shocks ................ 17
3.1 A Simple Statistical Model ............................... 19
3.2 Diffusive Shock Acceleration of Charged Particles ............ 20
3,3 Cycle Time and Momentum Gain for Particles
in Shock Acceleration ................................... 24
3.4 The Maximum Energy Attainable in Shock Acceleration ....... 25
3,5 Gyro-Resonant Scattering by Alfvtn Waves ................. 26
3.6 Maximum Energy for Specific Loss-Mechanisms ............. 28
3.7 Astrophysical Sites for Shock Acceleration .................. 30
3.8 Observational Evidence for Shock Acceleration .............. 32
3.9 "Realistic" Shock Acceleration: Non-Linear Effects ........... 34
3.10 Outstanding Problems ................................... 35
3.11 Relativistic Shocks ...................................... 37
3.12 Shock-Drift Acceleration ................................. 40
3.13 Conclusions ........................................... 41
References ..... . ................. ........,.., ............ . .... 41
E.A. Dorfi
Interstellar Medium and Supernova Remnants ..................... 43
Introduction .................................................. 43
1. Theories of the Interstellar Medium ......................... , 44
1.1 Constituents of the ISM ................................. 44
1.2 Interstellar Plasmas ..................................... 47
1.3 Radiation Fields ........................................ 56
1.4 Cosmic Rays .......................................... 60
IIIV
1.5 Magnetic Fields ........................................ 69
1.6 Further Remarks ....................................... 77
2. Supernova Remnants ....................................... 83
2.1 Free Expansion Phase ................................... 84
2.2 Sedov-Taylor Phase ..................................... 88
2.3 Cooling Phase ......................................... 92
2.4 Final SNR Evolution .................................... 95
2.5 Particle Acceleration in SNR's ............................ 99
2.6 X-Ray Emission from SNR's ............................. 111
2.7 Gamma-Ray Emission from SNR's ........................ 116
Conclusions ................................................... 122
References .................................................... 123
L. Vlahos
High Energy Emission from Normal Stars ......................... 129
1. Introduction ............................................... 130
1.1 Energy Flow and Particle Acceleration ..................... 130
1.2 Basic Concepts ......................................... 133
2. Spontaneous Emission ...................................... 134
2.1 Bremsstrahlung Emission ................................. 134
2.2 Cyclotron and Synchrotron Emission ....................... 138
3. Collective Plasma Emission .................................. 144
3.1 Plasma Radiation ....................................... 144
3.2 Electron Cyclotron Maser Instability ....................... 148
4. Observations .............................................. 152
4.1 Hard X-Ray Emission .................................. . 153
4.2 Radio Observations ..................................... 154
5. Summary and Conclusions .................................. 157
References .................................................... 158
A.R. King
Accretion in Close Binaries ..................................... 161
1. Introduction ............................................... 161
1.1 Energy Yields .......................................... 161
1.2 Radiation Spectrum ..................................... 162
1.3 Rotational Energy ....................................... 163
2. Accreting Binaries .......................................... 164
2.1 The Sizes of Binaries ................................... 164
2.2 The F~ldington Limit .................................... 164
3. Tidal Effects ............................................... 165
4. The Roche Potential ........................................ 166
5. Roche Lobe Overflow ....................................... 166
5.1 Occurrence ............................................ 166
5.2 The Degree of Roche Lobe Filling ......................... 168
5.3 Driving Mass Transfer ................................... 169
XI
6. Stellar Wind Accretion ...................................... 171
6.1 OB Supergiant X-Ray Binaries ............................ 171
6.2 Be-Star X-Ray Binaries .................................. 171
6.3 Mass and Angular Momentum Capture in Wind Accretion ..... 171
7. The Fate of the Accreted Matter ............................. 172
7.1 Roche Lobe Overflow ................................... 173
7.2 Stellar Wind Accretion .................................. 174
8. Accretion Discs ............................................ 174
8.1 Viscosity .............................................. 175
8.2 Viscous Dissipation ..................................... 176
8.3 The Magnitude of Viscosity .............................. 177
9. Disc Structure ............................................. 178
9.1 Steady Discs ........................................... 178
9.2 Vertical Disc Structure ............... .................... 180
10. Disc Stability .............................................. 180
11. Discs in Other Binaries ..................................... 182
12. Short.Period Binary Evolution ............................... 183
13. Secular Evolution of CVs ................................... 183
13.1 The Maximum Period ................................... 185
13.2 The Minimum Period ................................... 185
13.3 The Period Gap ........................................ 186
14. Short.Period LMXB Evolution ............................... 188
References ..................................................... 189
Part II High Accuracy Timing and Positional Astronomy
D.C. Backer
Pulsars - The New Celestial Clocks ............................... 193
1. Pulsars ................................................... 193
1.1 A Brief History of Neulxon Stars .......................... 193
1.2 Standard Model of Pulsars ............................... 195
1.3 Origin and Evolution of Isolated Neutron Stars ............... 198
2. Radio Astronomy Fundamentals ............................. 201
2.1 Radiation Properties ..................................... 201
2.2 Radio Telescopes ....................................... 203
2.3 Radio Astronomy Receivers .............................. 204
2.4 Propagation in the IntersteLlar Medium ..................... 206
2.5 Search Techniques ...................................... 209
2.6 Pulsar Timing Systems .................................. 211
3. Further Topics on Radio Wave Propagation ................... 213
3.1 Absorption ............................................ 213
3.2 Birefringence .......................................... 213
3.3 Scattering ............................................. 214
3.4 Solar Wind and Ionosphere ............................... 215
3.5 Relativistic Delay in Solar System Potential ................. 215
. Pulsar Timing 216
4.1 Arrival Time Measurement ............................... 217
4.2 Time Correction ........................................ 219
4.3 Space Correction ....................................... 221
4.4 Pulsar Parameter Estimation .............................. 222
4.5 Rotation Noise ......................................... 224
4.6 Astrometry ............................................ 226
5. Binary, Millisecond and Globular Cluster Pulsars .............. 226
5.1 Origin and Evolution ..................................... 226
5.2 Keplerian Binary Pulsar Timing ........................... 230
5.3 Relativistic Binary Pulsars ............................... 232
5.4 Globular Cluster Pulsars ................................. 233
5.5 Planets Around Pulsars .................................. 234
6. Pulsar Timing Array ....................................... 235
6.1 Time Coordinate ....................................... 235
6.2 Space Coordinate 237
6.3 Gravitational Wave Background ........................... 240
6.4 Pulsar Timing Array Experiments ........................... 247
References ..................................................... 250
J. Kovalevsky
The Mission HIPPARCOS ....................................... 255
1. What is Stellar Astrometry? .................................. 255
1.1 What is Stellar Astrometry? .............................. 255
1.2 Methods of Astrometry .................................. 255
1.3 Why Stellar Astrometry? ................................. 256
1.4 Present Situation and Expectations from HIPPARCOS ......... 257
2. Principles and Problems of Stellar Astrometry ................. 258
2.1 What Direction is of Interest to Astronomy? ................. 259
2.2 Astronomical Reference Frames ........................... 259
2.3 Application to Space Astrometry .......................... 260
3. The HIPPARCOS Mission ................................... 261
3.1 General Principle of HIPPARCOS ......................... 262
3.2 Description of the Satellite and of Its Payload ............... 263
3.3 Observing Strategy ..................................... 264
3.4 The INPUT Catalogue ................................... 266
4. Reduction of Grid Data ..................................... 267
4.1 Light Modulation by a Periodic Grid ....................... 267
4.2 Photon Counts Produced by the Modulation ................. 268
4.3 Light Modulation by a Single Slit ....... . ................. 270
4.4 Precision of the Results .................................. 271
5. Attitude Determination ..................................... 272
5.1 Satellite to Sky Transformation ............................ 272
5.2 Equations for Attitude Determination ....................... 274
5.3 Representation of the Attitude ............................ 275
5.4 Precision of Attitude Determination ........................ 277
IX
6. Reduction on a Great Circle ................................. 277
6.1 The Equations .......................................... 278
6.2 The Design Matrix ...................................... 279
6.3 Geometric Solution ..................................... 280
6.4 Attitude Smoothing ..................................... 280
6.5 Passive Stars .......................................... 281
6.6 Accuracy of the Solution ................................. 281
7. Computation of Astrometric Parameters ...................... 282
7.1 Sphere Reconstitution .... , .............................. 282
7.2 Astrometric Parameter Determination ....................... 283
8. Double and Multiple Star Treatment .......................... 284
8.1 First Approximation, Double Stars ......................... 285
8.2 Improvement of the Solution ............................. 286
9. Iterations ................................................. 287
9.1 Principle of Iterations ................................... 287
9.2 Setting the Sphere Rotation ............................... 288
9.3 Double and Multiple Star Inclusion ........................ 289
9.4 Expected Final Accuracies ............................... 289
10. TYCHO Program .......................................... 290
10.1 Preparation of the Reduction .............................. 291
10.2 Detection of Stars ...................................... 291
10.3 Identification .......................................... 292
10.4 Astrometry ............................................ 292
References .................................................... 293

List of participants
Anastasios Anastasiadis, (Greece) Thessaloniki
Jose Aparicio, .M Barcelona )niapS(
Bernhard Aringer, Wien )airtsuA(
Beeharry, Girish K. (France) Meudon
Theodora Boncheva, I. (Bulgaria) Shoumen
Marie-Helene Boulard, (France) Toulouse
Cognard, Ismael (France) Meudon
Francisco Colomer, G6teborg (Sweden)
Francois Cuisinier, (France) Strasbourg
Del Rio, Evileo Barcelona )niapS(
Petya Dimitrova, Shoumen )airagluB(
Egonsson, Jim Lund (Sweden)
Jonathan Ferreira, (France) Grenoble
Robert Greimel, Graz )airtsuA(
Milen Ivanov, Sofia )airagluB(
Kerschbaum, Franz Wien )airtsuA(
Mathias Kunz, (Germany) Ttibingen
Kuulkers, Eric Amsterdam )sdnalrehteN(
Rodger Manning, (England) Birmingham
Sergios Maravelias, (Greece) Athens
Josep Marti-Ribas, Barcelona )niapS(
Karin Muglach, Graz )airtsuA(
Marta Peracaula, Barcelona )niapS(
Benoite Pfeiffer, (France) Toulouse
Prins, Sacha Amsterdam )sdnalrehteN(
Eric Quemerais, (France) Buisson le Verrieres
Margaret Saphonova, Moscow )aissuR(
Christine Schmitz-Fraisse, (France) Toulouse
Mathias Schultheis, Wien )airtsuA(
Siopis, Christos (Greece) Ioannina
Torkelsson, Ulf Lund (Sweden)
Massimo Villata, (Italy) Torino
Wyn, Graham Leicester )dnalgnE(
Zamanov, Radoslav Smoljan )airagluB(