Physics of Active Galactic Nuclei at all Scales

243 Pages·2006·6.11 MB·English

by  H. Netzer (auth.)

Lecture Notes in Physics
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Danielle Alloin Rachel Johnson
Paulina Lira (Eds.)
Physics of
Active Galactic Nuclei
at all Scales
ABC
Editors
DanielleAlloin PaulinaLira
CEA UniversityofChile
Saclay-OrmedesMerisiers DepartmentofAstronomy
91191Gif-sur-YvetteCedex Casilla36D
France Santiago,Chile
E-mail:[email protected] E-mail:[email protected]
RachelJohnson
OxfordUniversity
DepartmentofPhysics
KebleRoad
Oxford,OX13RH,U.K.
E-mail:[email protected]
D. Alloin et al., Physics of Active Galactic Nuclei at all Scales, Lect. Notes Phys. 693
(Springer,BerlinHeidelberg2006),DOI10.1007/b11550280
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Preface
ThestudyofthephysicalprocessesatworkinActiveGalacticNuclei(AGN)
haskeptalargenumberofastronomersbusysincethediscovery,intheearly
sixties, of the first radio galaxies and quasars. After a few decades of debate
there is now a clear consensus about the source of energy in AGN, namely
gravitational energy released through matter accretion onto a massive black
hole.
The most commonly accepted ideas regarding AGN are pictured in the
so-called AGN unified model, although one should remember that this is
still a “working” model. Tremendous progress has been made in unveiling,
analyzing, and modeling the different components in AGN: the accretion
disk, the jets of relativistic particles, the x-ray absorber close to the central
engine,the“torus”thatfunnelstheionizingradiation,thesurroundingclouds
of dense material in the broadline region and narrowline region, the cool
molecular and dusty material around the torus, as well as jet-induced effects
on larger scales. Yet, it remains to incorporate all these components and
physical processes into a self-consistent AGN model that would take into
account, and predict, all the facets of AGN activity. The mere process of
matter fueling is far from being totally understood and neither is the link of
theAGNwithitshostgalaxy.Thebirthandgrowthofmassiveblackholesin
the universe is a related question to be investigated and is of prime interest
for cosmology. A wealth of new observational constraints about the physical
processes taking place in AGN has recently been made available, thanks
to ongoing key space missions (probing in particular their x-ray emission),
largeground-basedtelescopes,andhighspatialresolutiontechniquessuchas
adaptive optics and interferometry. Therefore, it is both exciting and timely
to see how these additional constraints fit in with model predictions and to
explore the new perspectives they bring to the field.
In order to contribute to this goal, we organized the International Work-
shop,“PhysicsofActiveGalacticNucleiatallScales”,whichwasheldatthe
European Southern Observatory in Santiago, Chile, from December 3 to 6,
2003. The meeting was sponsored jointly by the Conicyt/FONDAP Center
for Astrophysics, the European Southern Observatory, and the Calan Ob-
servatory of Universidad de Chile. The Workshop was intended for training
young researchers and students: it included a series of invited reviews, each
VI Preface
followed by oral contributions of topical relevance, and was completed by
a rich display of posters. Although the emphasis was on providing a solid
theoreticalbase,appropriateresultsfromrecentobservationsacrosstheelec-
tromagnetic spectrum were discussed, which made this Workshop extremely
enlightening. The reviews have been prepared for publication and constitute
the bulk of this volume. We are grateful to the reviewers for their generous
and enthusiastic contributions.
The Workshop was opened with a tutorial by Hagai Netzer, providing
a comprehensive picture of AGN physics. He pointed out that in spite of
the remarkable insights into the AGN phenomenon at present, some key
questions are still open. One of them is the “energy budget problem”, which
isthelargediscrepancybetweentheenergyoutputrequiredfromtheobserved
emission line spectrum and that extrapolated from the observed continuum
energydistribution.Anotherquestionreferstothedetailedunderstandingof
the physical processes hidden within the so-called alpha parameter used to
parameterize the viscosity in the accretion disk.
Following the tutorial, and in the framework of the AGN unified model,
subsequent reviews and discussions about AGN subsystems were given by
specialists in the field. Diana Worrall and Bradley Peterson focused on the
physicsofmaterialintheclosevicinityofthecentralsourceandonrelatedra-
diativeprocesses,discussingrelativisticjetsandthebroadlineregion.Moving
to larger scales, Bob Fosbury, Jack Gallimore, and Moshe Elitzur reviewed
the physics of gas further away but still exposed to the intense ultraviolet
radiation field from the AGN, as well as of molecular and dusty material
surviving such a harsh environment.
QuestionsabouttheAGNfuelingandtheAGNrelationshipwithitshost
galaxy were discussed by Sharda Jogee. Very recent results from space x-
ray missions are shedding new light on the evolution of the AGN luminosity
functionwithredshiftandontheAGN-galaxyformationscenario:thesewere
presented by Niel Brandt and Omar Almaini.
Thorough reviews on the forefront instrumentation available today in
Chile-based observatories were given by Chris Lidman and Malcolm Smith,
which, however, are not provided in this volume.
The workshop was attended by around seventy participants, with a re-
markable delegation from South America. It provided the ideal format and
sizetoboostexchangesanddiscussionsandinthis,itmettheoriginalgoalsof
theorganizers,DanielleAlloin,PoshakGandhi,andRachelJohnsonatESO;
and Paulina Lira, Sebastian Lopez, and Jose Maza at Calan Observatory.
WegratefullyacknowledgethevaluablesupportfromMs.PamelaBristow
at ESO/Garching in the editing work of this volume.
Garching and Santiago Danielle Alloin
July 2005 Rachel Johnson
Paulina Lira
Contents
Active Galactic Nuclei: Basic Physics and Main Components
H. Netzer ...................................................... 1
1 Terminology, Classification and Abbreviations................... 1
2 Black Holes................................................. 1
3 Accretion Disks ............................................. 4
4 Physical Processes in AGN Gas ............................... 12
5 Main Components of AGN ................................... 25
6 Summary................................................... 37
References ..................................................... 37
Multiwavelength Evidence of the Physical Processes
in Radio Jets
D.M. Worrall and M. Birkinshaw ................................. 39
1 Introduction ................................................ 39
2 Radiative Processes.......................................... 40
3 Effects of Bulk Relativistic Motion ............................ 46
4 The External Medium ....................................... 48
5 Simple Radio-Jet Models ..................................... 52
6 The Interpretation of Multiwavelength Data
in Terms of Physical Parameters .............................. 56
7 Conclusion ................................................. 71
References ..................................................... 71
The Broad-Line Region in Active Galactic Nuclei
B.M. Peterson.................................................. 77
1 Introduction ................................................ 77
2 Basic Inferences about the Line-Emitting Gas................... 78
3 Broad Emission-Line Variability
and Theory of Reverberation Mapping ......................... 81
4 Reverberation Results........................................ 86
5 What is the BLR?........................................... 91
6 What will it Take to Map the Broad-Line Region?............... 95
7 Some Obvious Questions to Keep in Mind ...................... 97
8 Summary................................................... 97
References ..................................................... 99
VIII Contents
Cold Gas Near Active Galactic Nuclei
J.F. Gallimore, M. Elitzur, S.A. Baum ............................ 101
1 Background ................................................ 101
2 Radio Observations.......................................... 104
3 Infrared SEDs and Modeling.................................. 113
4 Future Observations ......................................... 117
References ..................................................... 118
AGN Beyond the 100pc Scale
R.A.E. Fosbury................................................. 121
1 Introduction ................................................ 121
2 AGN–host Interactions....................................... 122
3 Observational Techniques and Examples........................ 126
4 What Next? ................................................ 139
5 Further Reading ............................................ 140
References ..................................................... 141
The Fueling and Evolution of AGN:
Internal and External Triggers
S. Jogee ....................................................... 143
1 Introduction ................................................ 143
2 BH Demographics and BH-Bulge-Halo Correlations.............. 144
3 Central Issues in Fueling AGN and Starbursts................... 147
4 Hubble Type and Colors of AGN Hosts ........................ 154
5 Interactions and AGN/Starburst Activity ...................... 156
6 Large-Scale Bars in Starbursts/AGN Hosts ..................... 160
7 Nuclear Bars................................................ 169
8 Nuclear Spirals and AGN/Starburst Activity.................... 171
9 From Hundred pc to Sub-pc Scales ............................ 174
10 Summary and Future Perspectives............................. 175
References ..................................................... 179
X-Ray Survey Results on Active Galaxy Physics
and Evolution
W.N. Brandt, D.M. Alexander, F.E. Bauer, C. Vignali .............. 185
1 Introduction ................................................ 185
2 Chandra and XMM-Newton Extragalactic Surveys............... 186
3 Some Implications for AGN Physics and Evolution .............. 191
4 Some Future Prospects....................................... 203
Some Recent Key References ..................................... 207
Contents IX
The Links Between AGN and Galaxy Formation
O. Almaini..................................................... 211
1 Supermassive Black Holes in Local Galaxies .................... 211
2 Models for Galaxy Formation ................................. 214
3 Observations of the High-Redshift Universe..................... 216
4 The Impact of AGN on their Environments..................... 220
5 Models for the Black-Hole/Bulge Relation ...................... 223
6 Summary and Future Prospects ............................... 225
References ..................................................... 227
Appendix: Acronyms Used in this Book ...................... 229
Index......................................................... 231