{"Affiliation":[{"label":"Affiliation","value":"Science, Faculty of","attrs":{"lang":"en","ns":"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool","classmap":"vivo:EducationalProcess","property":"vivo:departmentOrSchool"},"iri":"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool","explain":"VIVO-ISF Ontology V1.6 Property; The department or school name within institution; Not intended to be an institution name."},{"label":"Affiliation","value":"Physics and Astronomy, Department of","attrs":{"lang":"en","ns":"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool","classmap":"vivo:EducationalProcess","property":"vivo:departmentOrSchool"},"iri":"http:\/\/vivoweb.org\/ontology\/core#departmentOrSchool","explain":"VIVO-ISF Ontology V1.6 Property; The department or school name within institution; Not intended to be an institution name."}],"AggregatedSourceRepository":[{"label":"AggregatedSourceRepository","value":"DSpace","attrs":{"lang":"en","ns":"http:\/\/www.europeana.eu\/schemas\/edm\/dataProvider","classmap":"ore:Aggregation","property":"edm:dataProvider"},"iri":"http:\/\/www.europeana.eu\/schemas\/edm\/dataProvider","explain":"A Europeana Data Model Property; The name or identifier of the organization who contributes data indirectly to an aggregation service (e.g. Europeana)"}],"Campus":[{"label":"Campus","value":"UBCV","attrs":{"lang":"en","ns":"https:\/\/open.library.ubc.ca\/terms#degreeCampus","classmap":"oc:ThesisDescription","property":"oc:degreeCampus"},"iri":"https:\/\/open.library.ubc.ca\/terms#degreeCampus","explain":"UBC Open Collections Metadata Components; Local Field; Identifies the name of the campus from which the graduate completed their degree."}],"Creator":[{"label":"Creator","value":"Eilek, Jean Anne","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/terms\/creator","classmap":"dpla:SourceResource","property":"dcterms:creator"},"iri":"http:\/\/purl.org\/dc\/terms\/creator","explain":"A Dublin Core Terms Property; An entity primarily responsible for making the resource.; Examples of a Contributor include a person, an organization, or a service."}],"DateAvailable":[{"label":"DateAvailable","value":"2010-02-05T01:13:17Z","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/terms\/issued","classmap":"edm:WebResource","property":"dcterms:issued"},"iri":"http:\/\/purl.org\/dc\/terms\/issued","explain":"A Dublin Core Terms Property; Date of formal issuance (e.g., publication) of the resource."}],"DateIssued":[{"label":"DateIssued","value":"1975","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/terms\/issued","classmap":"oc:SourceResource","property":"dcterms:issued"},"iri":"http:\/\/purl.org\/dc\/terms\/issued","explain":"A Dublin Core Terms Property; Date of formal issuance (e.g., publication) of the resource."}],"Degree":[{"label":"Degree","value":"Doctor of Philosophy - PhD","attrs":{"lang":"en","ns":"http:\/\/vivoweb.org\/ontology\/core#relatedDegree","classmap":"vivo:ThesisDegree","property":"vivo:relatedDegree"},"iri":"http:\/\/vivoweb.org\/ontology\/core#relatedDegree","explain":"VIVO-ISF Ontology V1.6 Property; The thesis degree; Extended Property specified by UBC, as per https:\/\/wiki.duraspace.org\/display\/VIVO\/Ontology+Editor%27s+Guide"}],"DegreeGrantor":[{"label":"DegreeGrantor","value":"University of British Columbia","attrs":{"lang":"en","ns":"https:\/\/open.library.ubc.ca\/terms#degreeGrantor","classmap":"oc:ThesisDescription","property":"oc:degreeGrantor"},"iri":"https:\/\/open.library.ubc.ca\/terms#degreeGrantor","explain":"UBC Open Collections Metadata Components; Local Field; Indicates the institution where thesis was granted."}],"Description":[{"label":"Description","value":"Dynamical models of Seyfert nuclei and quasi-stellar objects are presented. The central energy source often postulated for these active objects provides a means of heating and ionizing the nuclear gas, and also exerts an outward force on the gas. Since the gas will be fully ionized, it will be nearly transparent to X-rays, while cosmic rays will interact strongly with it. Preliminary calculations of this \"ionization\" pressure on discrete clouds show that photons are unlikely to produce the high gas velocities relative to the nucleus which are indicated by the emission line profiles in Seyfert nuclei and the blueshifted quasar absorption lines, but that cosmic rays can accelerate the clouds up to these velocities.\r\nA more detailed calculation taking into account the dynamics of the gas is called for. A computer code was written to solve the spherically symmetric hydrodynaraic equations numerically. It uses a finite difference, implicit Eulerian scheme to solve the time dependent equations. As well as the mass conservation and momentum transfer equations, the numerical system includes an energy equation which allows for ionization and Coulomb heating, and radiative cooling. The code was used to obtain a set of nuclear evolutionary models. These models involve a static gas surrounding a quiescent energy source which turns on suddenly. A range of input physical parameters is represented: for sizes 0.1 to 1 pc, a total cosmic ray flux from 10\u2074\u00b3 ergs s\u207b\u00b9 to 10\u2074\u2078 ergs s\u207b\u00b9, a gas density of 10\u2074 to 10\u2078 cm\u207b\u00b3, a lowest particle energy in a power law spectrum of 0.1 to 10.0 MeV, and a central mass of 10\u2078 or 10\u2079 M\u20d9.\r\n\r\nSuch soft cosmic rays have a very short absorption length in the nuclear gas. This means a narrow region in radial extent will gain the momentum of the cosmic ray beam, and an outward moving shell will form. It snowplows the cooler gas ahead of it and leaves a less dense, hot cavity behind. This thin cavity reaches temperatures of 10\u2078 K, and the dense shell reaches an equilibrium temperature in the range 10\u2074-10\u2075 K. The shell velocities increased as the cosmic ray flux was increased, ranging from 500 to 8000 km s\u207b\u00b9.\r\nThe lifetime of this phenomenon is the time for the shell to escape the nuclear region, which is only a few parsecs across. At these velocities, the timescale is only 10\u00b3 to 10\u2074 years. This suggests repetitive rather than continuous activity of the central source. A quiescent phase would allow replenishment of the gas from extra-nuclear stellar sources.\r\nThe interface between the hot cavity and the shell is Rayleigh-Taylor unstable with a fragmentation time approximately equal to the shell escape time. This may explain the cloud structure observed in these objects. Thermal instabilities may also arise if the central source turns off.\r\nPrediction of the sources of the permitted and forbidden emission lines is dependent on the behavior of the instabilities. The very dense shell suggests a physical distinction between the regions producing the two types of spectra, which may explain the wider permitted lines in some sources. The hot gas near the energy source will produce thermal X-rays. The luminosity and temperature predicted for the X-rays is consistent with observations.","attrs":{"lang":"en","ns":"http:\/\/purl.org\/dc\/terms\/description","classmap":"dpla:SourceResource","property":"dcterms:description"},"iri":"http:\/\/purl.org\/dc\/terms\/description","explain":"A Dublin Core Terms Property; An account of the resource.; Description may include but is not limited to: an abstract, a table of contents, a graphical representation, or a free-text account of the resource."}],"DigitalResourceOriginalRecord":[{"label":"DigitalResourceOriginalRecord","value":"https:\/\/circle.library.ubc.ca\/rest\/handle\/2429\/19617?expand=metadata","attrs":{"lang":"en","ns":"http:\/\/www.europeana.eu\/schemas\/edm\/aggregatedCHO","classmap":"ore:Aggregation","property":"edm:aggregatedCHO"},"iri":"http:\/\/www.europeana.eu\/schemas\/edm\/aggregatedCHO","explain":"A Europeana Data Model Property; The identifier of the source object, e.g. the Mona Lisa itself. This could be a full linked open date URI or an internal identifier"}],"FullText":[{"label":"FullText","value":"COSMIC BAY ACCELERATION OF GAS IN ACTIVE GALACTIC NUCLEI by JEAN ANNE EILEK A., U n i v e r s i t y of C a l i f o r n i a , B e r k e l e y , 1968 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n the Department of GEOPHYSICS AND ASTRONOMY We accept t h i s t h e s i s as comforming t o the re g u i r e d ^ s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA J u l y 1975 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Co lumb ia , I ag ree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d that c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i thout my w r i t t e n p e r m i s s i o n . Depa rtment The U n i v e r s i t y o f B r i t i s h Co lumbia Vancouver 8, Canada Date i ABSTRACT Dynamical models of S e y f e r t n u c l e i and q u a s i - s t e l l a r ' o b j e c t s are presented. The c e n t r a l energy source o f t e n p o s t u l a t e d f o r these a c t i v e o b j e c t s p r o v i d e s a means of h e a t i n g and i o n i z i n g the n u c l e a r gas, and a l s o e x e r t s an\/outward f o r c e on the gas. Si n c e the gas w i l l be f u l l y ionize\/d, i t w i l l be n e a r l y t r a n s p a r e n t t o X-rays, while cosmic rays w i l l i n t e r a c t s t r o n g l y with i t . P r e l i m i n a r y c a l c u l a t i o n s of t h i s \" i o n i z a t i o n \" p ressure on d i s c r e t e c l o u d s show that photons are u n l i k e l y to produce the high gas v e l o c i t i e s r e l a t i v e to the nucleus which are i n d i c a t e d by the emission l i n e p r o f i l e s i n S e y f e r t n u c l e i and the b l u e s h i f t e d quasar a b s o r p t i o n l i n e s , but that cosmic r a y s can a c c e l e r a t e the c l o u d s up to these v e l o c i t i e s . A more d e t a i l e d c a l c u l a t i o n t a k i n g i n t o account the dynamics of the gas i s c a l l e d f o r . A computer code was w r i t t e n to s o l v e the s p h e r i c a l l y symmetric hydrodynaraic equations n u m e r i c a l l y . I t uses a f i n i t e d i f f e r e n c e , i m p l i c i t E u l e r i a n scheme to s o l v e the time dependent equ a t i o n s . As w e l l as the mass c o n s e r v a t i o n and momentum t r a n s f e r e q u a t i o n s , the numerical system i n c l u d e s an energy equation which a l l o w s f o r i o n i z a t i o n and Coulomb hea t i n g , and r a d i a t i v e c o o l i n g . The code was used t o o b t a i n a set of n u c l e a r e v o l u t i o n a r y models. These models i n v o l v e a s t a t i c gas surrounding a q u i e s c e n t energy source which t u r n s on suddenly. A range of i n p u t p h y s i c a l parameters i s re p r e s e n t e d : f o r s i z e s 0.1 to 1 pc, a t o t a l cosmic ray f l u x from 10*^ ergs s ~ l to 1 0 4 8 ergs s _ 1 , a gas d e n s i t y of 10* to 10 8 cm - 3, a lowest p a r t i c l e energy i n a power law spectrum of 0.1 to 10.0 MeV, and a c e n t r a l mass of 10 8 or 10 ' f l 0 . i i Such s o f t cosmic rays have a very s h o r t a b s o r p t i o n l e n g t h i n the n u c l e a r gas. T h i s means a narrow r e g i o n i n r a d i a l extent w i l l g ain the momentum of the cosmic ray beam, and an outward moving s h e l l w i l l form. I t snowplows the c o o l e r gas ahead of i t and l e a v e s a l e s s dense, hot c a v i t y behind. T h i s t h i n c a v i t y reaches temperatures of 10 8 K, and the dense s h e l l reaches an e q u i l i b r i u m temperature i n the range 10 4-10 5 K. The s h e l l v e l o c i t i e s i n c r e a s e d as the cosmic ray f l u x was i n c r e a s e d , ranging from 500 to 8000 km s - 1 . The l i f e t i m e of t h i s phenomenon i s the time f o r the s h e l l t o escape the n u c l e a r r e g i o n , which i s only a few parsecs a c r o s s . At these v e l o c i t i e s , the t i m e s c a l e i s only 10 J to 10 4 y e a r s . T h i s suggests r e p e t i t i v e r a t h e r than continuous a c t i v i t y of the c e n t r a l source. A q u i e s c e n t phase would allow replenishment of the gas from e x t r a - n u c l e a r s t e l l a r s o u r c e s . The i n t e r f a c e between the hot c a v i t y and the s h e l l i s R a y l e i g h - T a y l o r u n s t a b l e with a fragmentation time approximately equal to the s h e l l escape time. T h i s may e x p l a i n the c l o u d s t r u c t u r e observed i n these o b j e c t s . Thermal i n s t a b i l i t i e s may a l s o a r i s e i f the c e n t r a l source t u r n s o f f . P r e d i c t i o n of the sources of the p e r m i t t e d and f o r b i d d e n emission l i n e s i s dependent on the behavior of the i n s t a b i l i t i e s . The very dense s h e l l suggests a p h y s i c a l d i s t i n c t i o n between the r e g i o n s producing the two types of spectra,- which may e x p l a i n the wider p e r m i t t e d l i n e s i n some sour c e s . The hot gas near the energy source w i l l produce thermal X-rays. The l u m i n o s i t y and temperature p r e d i c t e d f o r the X-rays i s c o n s i s t e n t with o b s e r v a t i o n s . i i i TAELE OF CONTENTS page An ABSTRACT precades t h i s i TABLE OF CONTENTS. There f o l l o w s a i i i LIST OF TABLES, a V LIST OF FIGURES, and v i ACKNOWLEDGEMENTS. v i i i CHAPTER I i s an INTRODUCTION t o t h i s t h e s i s , 1 wherein some i n t r i g u i n g t a c t s about S e y f e r t g a l a x i e s are presented, and a b r i e f d i s c u s s i o n of the plan of t h i s t h e s i s i s l a i d out. In CHAPTER I I , SIMPLE MODELS of the gas are 8 di s c u s s e d i n terms of what p h y s i c a l q u a n t i t i e s can be i n f e r r e d from o b s e r v a t i o n s . An attempt to estimate c l o u d a c c e l e r a t i o n f o l l o w s , and t h i s f u r t h e r encourages CHAPTER I I I , which presents the CONTINUOUS FLOW 33 CALCULATIONS. The model to be c a l c u l a t e d i s d e s c r i b e d , and the m i c r o s c o p i c p h y s i c s are c o n s i d e r e d . CHAPTER IV d e s c r i b e s the NUMERICAL CODE w r i t t e n 48 to s o l v e the hydrodynamic e q u a t i o n s . These c a l c u l a t i o n s form the b a s i s of CHAPTER V, where the EVOLUTION OF THE GAS i s 70 presented i n terms of s e v e r a l numerical models. . These are f u r t h e r d i s c u s s e d i n CHAPTER VI, wherein the IMPLICATIONS of these 155 c a l c u l a t i o n s are i n v e s t i g a t e d , i n c l u d i n g the s t a b i l i t y of the models to f r a g a i e n t a t i o n , and t h e i r r e l a t i o n to o b s e r v a t i o n s . F i n a l l y , i n CHAPTER VII, the work i s summarized, CONCLUSIONS drawn and s u g g e s t i o n s f o r f u t u r e work are given. BIBLIOGRAPHY LIST OF SYMBOLS APPENDIX I pr e s e n t s some r a t h e r lengthy c a l c u l a t i o n s of the ATTENUATION OF THE IONIZING FLUX, whether cosmic r a y s or photons. APPENDIX I I d i s c u s s e s the NUMERICAL STABILITY of the computer program and pr e s e n t s v a r i o u s t e s t s of same. APPENDIX I I I i s a l i s t i n g of the COMPUTER CODE. LIST OF TABLES I . V e l o c i t y S t r u c t u r e Of Line P r o f i l e s 11 I I . Parameters Of A Standard A c t i v e Nucleus 17 I I I . Cosmic Ray A c c e l e r a t i o n Of F r e e l y Expanding Clouds 31 \/ IV. Computational Parameters \/ 52 V. The Hydrodynamic Equations \/ 54 VI. The C a l c u l a t i o n C y c l e 68 V I I . C o o l Mode Models, Computational Parameters 93 V I I I . S h a l l Models, P h y s i c a l Parameters 153 i X . Comparison Of Models With O b s e r v a t i o n s 167 v i LIST OF FIGURES 0 . S e y f e r t Nuclear S p e c t r a 18 1 . R a d i a t i v e C o o l i n g Curve 72 2 . I o n i z a t i o n S t r u c t u r e 76 3 . X Ray Model - Densi t y 81 4 . X Ray Model - V e l o c i t y 82 5 . Hot Mode C a l c u l a t i o n . 90 6 . S h e l l Model 1 (40 point) - D e n s i t y 100 7 . S h e l l Model 1 (40 point) - V e l o c i t y 101 8a. S h e l l Model 1 (40 Point) - Temperature 103 8b. S h e l l Model 1 (40 Point) - Cosmic Ray A b s o r p t i o n 105 9 . S h e l l Model 1 (40 point) - Density Contour 107 10 . S h e l l Model 1 (40 point) - V e l o c i t y Contour 108 11 . S h e l l Model 1 - B (t) And E (t) 110 12 . S h e l l Model 1 (60 point) - Density 112 13 . S h e l l Model 1 (60 point) - V e l o c i t y 113 14 . S h e l l Model 1 (60 point) - Density Contour 115 15 . S h e l l Model 1 (60 point) - V e l o c i t y Contour 116 16 . S h e l l Model 1 ( a d i a b a t i c ) - Density 118 17 . S h e l l Model 1 ( a d i a b a t i c ) - V e l o c i t y 119 18 . S h e l l V e l o c i t y v (t) - Models 1A, 1B, 2, 3 124 19 . S h e l l V e l o c i t y v (t) - Models 4, 5, 6, 7 131 20 . S h e l l Model 5 - Density 133 21 . S h e l l Model 5 - V e l o c i t y 134 2 2 . S h e l l Model 5 - Density Contour 136 23 . S h e l l Model 5 - V e l o c i t y Contour 137 23a- S h e l l Model 5 - Temperature 139 24 - S h e l l Model 6 - Density 14 1 v i i 25 . S h e l l Model 6 - V e l o c i t y 142 26 . S h e l l Model 6 - Density Contour 144 27 . S h e l l Model 6 - V e l o c i t y Contour 145 28 . S h e l l Model 7 - Density 147 29 . S h e l l Model 7 - V e l o c i t y 148 30 - S h e l l Model 7 - Density Contour 150 31 . S h e l l Model 7 - V e l o c i t y Contour 151 A. 1 S i m i l a r i t y S o l u t i o n - Density 196 A.2 S i m i l a r i t y S o l u t i o n - Temperature 197 A. 3 S i m i l a r i t y S o l u t i o n - V e l o c i t y 198 A.4 Homogeneous Sphere - Density 203 A.5 Homogeneous Sphere - Temperature 204 A. 6 Homogeneous Sphere - V e l o c i t y 205 A.7 Ha l f G r i d Te St 208 v i i i ACKNOWLEDGEMENTS The o r i g i n a l m o t i v a t i o n f o r t h i s problem arose through work with the DBC i s o c o n o b s e r v i n g group, which i n c l u d e d the e f f o r t s and i n s p i r a t i o n of Ann Gower, John Glaspey and Gordon Walker. My a d v i s o r , Jason Auman, provided much h e l p f u l d i s c u s s i o n and s p e c i f i c c r i t i c i s m of the p h y s i c a l concepts and numerical models, as d i d Greg Pahlman. The c a l c u l a t i o n s of Chapter I I owe much to s u g g e s t i o n s from L a r r y C a r o f f . Ian Easson provided v a l u a b l e a d v i c e on numerical methods. Ian Thompson a s s i s t e d i n producing t h i s t h e s i s , and Ingemar Olson o f f e r e d a f i n e c r i t i c a l edge. I am g r a t e f u l f o r support from UBC graduate f e l l o w s h i p s and from the N a t i o n a l Research C o u n c i l of Canada. F i n a l l y , I am indebted to many members of the department \u2014 e s p e c i a l l y Drs. Auman, Fahlman and Glaspey \u2014 f o r t h e i r moral support and undeserved p a t i e n c e over the y e a r s . a l l s t r o n g women 1 CHAPTER I INTRODUCTION Within the l a s t decade or so, a great deal of e f f o r t w i t h i n the a s t r o n o m i c a l community has turned toward i n v e s t i g a t i o n of many i n t e r e s t i n g e x t r a g a l a c t i c o b j e c t s , some of which have been newly d i s c o v e r e d , o t h e r s which are more f a m i l i a r but have r e c e n t l y seemed e s p e c i a l l y i n t r i g u i n g . Our p i c t u r e of the \" e x t r a g a l a c t i c nebulae\" has been extended from a v i s i o n of s t a t i c \" i s l a n d u n i v e r s e s \" of s t a r s to i n c l u d e some r a p i d l y changing, h i g h l y e n e r g e t i c o b j e c t s , with p o s s i b l y n o n - s t e l l a r components. Some of these e x t r a g a l a c t i c o b j e c t s vary over months or years, yet seem to c o n t a i n and produce as much energy as a normal s t e l l a r g a l a x y . Many of these o b j e c t s have been d i s c o v e r e d w i t h i n the l a s t three decades, but some have been f a m i l i a r much lon g e r than t h a t . The newly-discovered r a d i o s o u r c e s were i d e n t i f i e d with e x t e r n a l g a l a x i e s i n the 1950's (f o r Cyg A, e.g.., c f . B o l t o n and S t a n l e y , 1948, and Baade and Minkowski, -1954). These r a d i o g a l a x i e s o f t e n show a double s t r u c t u r e , l a r g e r than the o p t i c a l g a l a x y , which h i n t s a t e j e c t i o n from the nuc l e u s . Q u a s i - s t e l l a r o b j e c t s gained wide i n t e r e s t when str o n g r a d i o sources were i d e n t i f i e d with o p t i c a l s t a r l i k e o b j e c t s o f hig h r e d s h i f t ( for 3C 273, e.g., c f . Hazard, Mackey and Shimming, 1963, and Schmidt,. 1963). More r e c e n t l y , o b j e c t s of the BL Lac e r t a e c l a s s have been observed widely ( S t r i t t m a t t e r et a l . , 1972, f o r OJ 287; MacLeod et a l . , 1971, f o r BL L a c ) . On t h e oth e r hand, some of the g a l a x i e s now c l a s s i f i e d as S e y f e r t g a l a x i e s have been known as g a l a x i e s with broad n u c l e a r 2 e m i s s i o n l i n e s s i n c e almost the t u r n of the c e n t u r y . (Fath, 1908, on NGC 1068; Campbell and Moore, 1918, on NGC 4151.) S e y f e r t (1943) suggested that these g a l a x i e s c o n s t i t u t e a d i s t i n c t c l a s s . T h i s c l a s s i s c u r r e n t l y d e f i n e d as a l l g a l a x i e s \/ r e c o g n i z a b l e on Sky Survey p r i n t s with broad emission l i n e s and \/' a b r i g h t s e m i - s t e l l a r nucleus (Khachikian and Weedman, 1974). These emission l i n e s are c h a r a c t e r i s t i c of a t h i n , e x c i t e d hydrogen gas with m u l t i p l e i o n i z a t i o n s t a t e s of helium and hea v i e r elements present. Besides the emission l i n e s , S e y f e r t n u c l e i o f t e n d i s p l a y a nonthermal o p t i c a l continuum, s t r o n g (probably thermal) i n f r a r e d e m i s s i o n , and i n two cases show X-ray e m i s s i o n . Most of the g a l a x i e s are a s s o c i a t e d with r a d i o s o u r c e s , although these are o f t e n r e l a t i v e l y weak. Rapid v a r i a b i l i t y has been observed i n the emission l i n e s or the continuum i n some cases. ( D e t a i l e d d e s c r i p t i o n s and r e f e r e n c e s w i l l be given below.) The s p e c t r a of the other e n e r g e t i c e x t r a g a l a c t i c o b j e c t s mentioned above show i n t e r e s t i n g s i m i l a r i t i e s t o S e y f a r t n u c l e a r s p e c t r a . The emi s s i o n l i n e s c h a r a c t e r i s t i c of S e y f e r t n u c l e i appear i n quasars (Burbidge 1967), and sometimes i n e x t r a g a l a c t i c r a d i o sources and other types of g a l a x i e s (Osterbrock and M i l l e r , 1975; Burbidge, 1970 and r e f e r e n c e s t h e r e i n ) . The emission l i n e s do vary from o b j e c t to o b j e c t i n t h e i r r e l a t i v e i n t e n s i t i e s and i o n i z a t i o n l e v e l s present. The quasar 3C 273 has been observed i n the X-ray band and s e v e r a l quasars have been observed i n the i n f r a r e d (Margon et ajL. , 1975; Rieke and Low, 1972). * O p t i c a l and r a d i o continuum v a r i a b i l i t y has been r e p o r t e d i n at l e a s t twelve quasars on a time s c a l e of 3 years or l e s s ( r e f e r e n c e s i n Burbidge, 1967, Schmidt, 1969, and Kellerman and P a u l i n y - T o t h , 1968). The VLBI s t r u c t u r e a l s o v a r i e s on t h i s time s c a l e i n some quasars (Gubbay et a l . , 1969, Moff e t et a l . , 1971} . \/ BL Lacertae o b j e c t s a l s o e x h i b i t non-therma'l c o n t i n u o u s r a d i a t i o n which v a r i e s on a time s c a l e of years' or l e s s ( E p s t e i n et a l . , 1972; MacLeod e t a l . , 197 1; Stannard e t a l . , 1975). The VLBI s t r u c t u r e of BL Lac has been observed to change over a year (Clark e t a l . , 1973). No s p e c t r a l l i n e s have been confirmed i n i t s spectrum (Oke and Gunn, 1974; Baldwin et a l - , 1975). I t may be dangerous to g e n e r a l i z e about these v a r i e d o b j e c t s as a s i n g l e group, based on these minimal o b s e r v a t i o n s . Nonetheless, the f a c t stands out t h a t a l l show evidence of v i o l e n t a c t i v i t y . The presence of a hot nebular gas, nonthermal s p e c t r a and X-ray s p e c t r a which may be due to r e l a t i v i s t i c p a r t i c l e s , the s t r u c t u r a l h i n t s at e j e c t i o n of matter, the high gas v e l o c i t y i m p l i e d from the l i n e p r o f i l e s , and the r a p i d v a r i a b i l i t y a l l i n d i c a t e a c t i v i t y . These o b j e c t s have t h e r e f o r e been c o n s i d e r e d i n the l i t e r a t u r e as examples of \" a c t i v e o b j e c t s \" or \"compact nonthermal s o u r c e s \" . T h i s t h e s i s i s mainly concerned with S e y f e r t n u c l e i . The models to be d i s c u s s e d , however, seem t o o v e r l a p p o s s i b l e models of these other a c t i v e o b j e c t s , and f o r t h i s reason I c o n s i d e r the d i s c u s s i o n here to apply to a \" t y p i c a l \" a c t i v e g a l a c t i c nucleus. S e y f e r t n u c l e i and r a d i o g a l a x i e s put out l a r g e amounts of energy. I f guasars and BL Lac o b j e c t s are at c o s m o l o g i c a l d i s t a n c e s , they too are very e n e r g e t i c s o u r c e s . These high t o t a l e n e r g i e s and high l u m i n o s i t i e s have not been 4 s a t i s f a c t o r i l y e x p l a i n e d , although there has been much d i s c u s s i o n of the energy source. Suggestions f o r the energy source i n c l u d e dense s t a r c l u s t e r s ( S p i t z e r and Saslaw, 1966, S p i t z e r and Stone, 1967, Shara and Shaviv, 1974); c l u s t e r s of \/ supernovae (Colgate, 1967) ; massive r o t a t i n g condensed o b j e c t s (Morrison 1969); b l a c k holes (Wolfe and Burbidge, 1970, H i l l s , 1975); and more w h i m s i c a l l y perhaps, white h o l e s (Jeans, 1929, N a r l i k a r , Appa Rao and Dadhich, 1974) and f i r e b r e a t h i n g dragons ( S h i e l d s , Oke and Sargent, 1972). 1 A more pragmatic approach to these o b j e c t s has been to i n v e s t i g a t e only the secondary e f f e c t s of the energy source. T h i s approach t r e a t s i n d e t a i l the s t r u c t u r e of the matter producing the observed r a d i a t i o n , about which we have o b s e r v a t i o n a l evidence, without s p e c i f y i n g the energy source. In t h i s t h e s i s , T w i l l f o l l o w the l a t t e r , w e l l - e s t a b l i s h e d t r a d i t i o n . I w i l l make use of a l a r g e energy i n p u t , about that of an e n t i r e s t e l l a r galaxy, while t o t a l l y i g n o r i n g i t s o r i g i n . T h i s i s j u s t i f i e d , because whatever the o r i g i n a l source of the energy, i t must couple to the matter producing the observed spectrum by means of a more p r o s a i c mechanism, such as e n e r g e t i c p a r t i c l e s or photons. My main focus here w i l l be the dynamics of the matter r e s u l t i n g from t h i s energy i n p u t , s p e c i f i c a l l y of the gas producing the s p e c t r a l l i n e s , s i n c e the re c a n t high r e s o l u t i o n o b s e r v a t i o n s of these l i n e s allow d e t a i l e d i n v e s t i g a t i o n of t h i s n u c l e a r component. Where r e l e v a n t , * S i n c e some of these i d e a s occur throughout the l i t e r a t u r e on S e y f e r t g a l a x i e s and quasars, the r e f e r e n c e s c i t e d here can only be r e p r e s e n t a t i v e , r a t h e r than e x h a u s t i v e . 5 p a s s i n g remarks w i l l be made on the other s p e c t r a l components. Most of t h e p r e v i o u s work on these o b j e c t s has i n v e s t i g a t e d the i o n i z a t i o n s t r u c t u r e and r a d i a t i o n mechanisms, with the assumption of a non-evolving nucleus. T h i s work w i l l a t t e n d to the dynamical e v o l u t i o n of the gas, r a t h e r than attempting to p r e d i c t the observed l i n e s i n d e t a i l . The s p e c t r a l l i n e s , both a b s o r p t i o n and e m i s s i o n , show d e t a i l e d s t r u c t u r e which i s probably due to high v e l o c i t y motions. These v e l o c i t i e s are u s u a l l y w e l l above the escape v e l o c i t y , which i n d i c a t e s mass i s being l o s t . Models of t h i s mass l o s s can be found i n the l i t e r a t u r e . Y a h i l and O s t r i k e r (1973), Wolfe (1974) and I p a v i c h (1975) present v a r i o u s time independent \" g a l a c t i c wind\" models. Matthews and Baker (1971) c a l c u l a t e d non-steady winds from normal e l l i p t i c a l g a l a x i e s . Matthews (1974), and Kippenhahn, Perry and Roser (1974) among o t h e r s , c o n s i d e r e d r a d i a t i v e a c c e l e r a t i o n of d i s c r e t e gas c l o u d s near the nucleus. Models of the i o n i z a t i o n or l i n e f o r m a t i o n mechanisms (Osterbrock and Parker, 1965, MacAlpina, 1972, Davidson, 1973, Ptak and Stoner, 1973) g e n e r a l l y p o s t u l a t e a c e n t r a l p o i n t source of i o n i z a t i o n i n s i d e the o p t i c a l gas. T h i s w i l l a f f e c t the gas d y n a m i c a l l y , which has not been t r e a t e d q u a n t i t a t i v e l y i n t h e i r models. These models can be improved by t r e a t i n g more of the p h y s i c a l c o n d i t i o n s i n d e t a i l and r e d u c i n g the number of assumptions needed. The thermal s t a t e of the gas can be determined once the h e a t i n g mechanism and the amount of ambient gas are s p e c i f i e d , s i n c e the c o o l i n g f u n c t i o n of nebular gas i s w e l l known. The d i f f e r e n t f o r c e s t h a t photons and e n e r g e t i c 6 p a r t i c l e s e x e r t on the gas can be determined. A time-dependent hydrodynamic c a l c u l a t i o n i s the obvious e x t e n s i o n of the steady s t a t e or d i s c r e t e models mentioned above. T h i s t h e s i s c o n s i s t s of a f i r s t attempt at t h i s problem, namely, s p h e r i c a l l y symmetric numerical hydrodynamic models of the response of a \" t y p i c a l \" a c t i v e nucleus to a s m a l l c e n t r a l source. The models presented here are too simple to p r e d i c t a l l o b s e r v a t i o n a l d e t a i l s . They i g n o r e important components of the n u c l e a r dynamics, such as r o t a t i o n and magnetic f i e l d s , and they give only a c u r s o r y e x p l a n a t i o n of a l l the s p e c t r a l components. However, they provide a c o n s i s t e n t p i c t u r e of the e n e r g e t i c s and e v o l u t i o n which agrees with other e s t i m a t e s of mass sources and n u c l e a r e n e r g i e s . The l a y o u t of the r e s t of the t h e s i s i s as f o l l o w s . In Chapter I I , the t y p i c a l a c t i v e nucleus i s d e s c r i b e d i n terms of o b s e r v a t i o n a l evidence so f a r a v a i l a b l e . (A l i s t o f symbols used i s g i v e n f o l l o w i n g the b i b l i o g r a p h y . ) C h a r a c t e r i s t i c p h y s i c a l parameters are summarized f o r the Standard A c t i v e Nucleus . Then a d i s c r e t e - c l o u d c a l c u l a t i o n i l l u s t r a t e s the d i f f e r i n g e f f e c t s of cosmic rays and photons i n a c c e l e r a t i n g t h e gas. Chapter I I I d e s c r i b e s the d e t a i l e d model t o be t r e a t e d n u m e r i c a l l y , i n terms of the geometry, the i n i t i a l s t a t e , and the m i c r o s c o p i c p h y s i c s i n v o l v e d . (Appendix I e v a l u a t e s the s p a t i a l .attenuation of the cosmic ray beam.) Chapter IV d e s c r i b e s the f i n i t e d i f f e r e n c e E u l e r i a n scheme that was w r i t t e n to s o l v e the time dependent hydrodynamic e q u a t i o n s of the gas. (Appendix I I d i s c u s s e s the accuracy of the c a l c u l a t i o n s , and Appendix I I I g i v e s a FORTRAN l i s t i n g of 7 the code.) S e v e r a l n u m e r i c a l models were produced, c o v e r i n g a range of the p h y s i c a l parameters, and they are d e s c r i b e d i n Chapter V. F i n a l l y , Chapter VI i n c l u d e s the probable f u t u r e e v o l u t i o n of the numerical models, and the i m p l i c a t i o n s of these models f o r o b s e r v a t i o n s and f o r the o v e r a l l p i c t u r e of a c t i v e n u c l e i . 8 CHAPTER I I SIMPLE MODELS OF THE OPTICALLY EMITTING REGION In t r y i n g to b u i l d models of a c t i v e n u c l e i , I w i l l c o n s i d e r mainly the o p t i c a l spectrum, s i n c e the most d e t a i l e d o b s e r v a t i o n s are of t h i s p o r t i o n of the spectrum. T h i s i n c l u d e s the e m i s s i o n and a b s o r p t i o n l i n e s , as w e l l as the nonthermal continuum. Much work and s p e c u l a t i o n has been devoted to the nature of the \" o p t i c a l l y e m i t t i n g r e g i o n \" (OES) r e c e n t l y ; Burbidge (1970) and Rees and Sargent (1972) g i v e good reviews. O b s e r v a t i o n s Many p h y s i c a l parameters of the OEE can be esitraated from o b s e r v a t i o n s . These i n c l u d e the nature and s p a t i a l d i s t r i b u t i o n of the gas, the nature of the energy source or i t s c o u p l i n g to the gas, and the n u c l e a r g r a v i t a t i o n a l f i e l d . These are d i s c u s s e d i n o r d e r . 1. Geometry Of The E m i t t i n g Gas The s p e c t r a of a c t i v e n u c l e i show f o r b i d d e n l i n e s from i o n i z a t i o n s t a t e s of widely d i f f e r i n g e n e r g i e s , from [ O i l ] to [ F e X I V ] , and a recombination spectrum of hydrogen and helium (Burbidge, 1970). T h i s probably i n d i c a t e s a s p a t i a l s t r a t i f i c a t i o n of i o n i z a t i o n . T h i s s t r a t i f i c a t i o n c o u l d come from a gas around a s m a l l c e n t r a l source of i o n i z i n g r a d i a t i o n w i t h i n a gas c l o u d . Models i n which the source i s assumed to be a c o n t i n u a t i o n of the o p t i c a l continuum to higher e n e r g i e s are g i v e n by Davidson (1972), MacAlpine (1972), and S h i e l d s and Oke 9 (1975). Osterbrock and Parker (1965) p o i n t e d out the absence i n NGC 1068 of the 01II f l u o r e s c e n t l i n e s XN3312 and 3444. These l i n e s are e x c i t e d by H e l l Ly4 i n p l a n e t a r y nebulae; t h e i r absence (assuming He to be present) means the H e l l Lyd i s dest r o y e d somehow. Osterbrock and Parker suggest e n e r g e t i c protons generated by c l o u d c o l l i s i o n s at many p o i n t s of the OER as the i o n i z a t i o n mechanism. T h i s would allow the n e u t r a l H and He to c o e x i s t s p a t i a l l y with the OIII. S o u f f r i n (1969) has c r i t i c i z e d the suprathermal proton i o n i z a t i o n mechanism on the grounds t h a t an i o n i z a t i o n balance c o u l d not occur i n the temperature and d e n s i t y range i m p l i e d by the f o r b i d d e n l i n e r a t i o s . The models d i s c u s s e d below i n v o l v e an inhomogeneous, h i g h e r d e n s i t y gas, and t h i s problem does not appear. A s m a l l c e n t r a l energy source has been p o s t u l a t e d because of the v a r i a b i l i t y - on time s c a l e s of a few days or a month, up to a year - observed i n the o p t i c a l continuum (Pacholczyk and Heymann, 1968 ) as w e l l as i n the hydrogen Balmer l i n e s ( E i l e k et a l . , 1973, ) and hydrogen and helium a b s o r p t i o n l i n e s (Anderson and K r a f t , 1971 ) . The i d e a of a \" f i l l i n g f a c t o r \" was f i r s t i n t r o d u c e d by Oke and Sargent (1968). The f i l l i n g f a c t o r i s d e f i n e d as the f r a c t i o n of the e m i t t i n g volume occupied by dense c l o u d s . T h i s f r a c t i o n i s l e s s than u n i t y , s i n c e the volume i n f e r r e d from the Balmer l i n e e m i s s i v i t y i s l e s s than the volume c o r r e s p o n d i n g t o the a p p a r e n t l y r e s o l v e d extent of the [ O I I I ] l i n e s . They estimated the f i l l i n g f a c t o r as 1\/40; other e s t i m a t e s have been 10 as low as 10~ 3 (Bergeron and S a l p e t e r , 1973). D i r e c t evidence of the d u m p i n e s s of the gas i n g a l a c t i c n u c l e i comes from o b s e r v a t i o n s o f s t r u c t u r e i n the e m i s s i o n l i n e p r o f i l e s . (See, f o r i n s t a n c e , Walker, 1968, fiilek e t a l . , 1973, and Glaspey e t a l . , 1975, f o r NGC 1068; O l r i c h , 1973, and Walker, 1968, f o r NGC 4151; Anderson, 1971, f o r NGC 5548; Burbidge and Burbidge, 1965, f o r NGC 1275; Anderson, 1973, f o r NGC 7469.) These c l o u d s have very high r e l a t i v e v e l o c i t i e s , on the o r d e r of s e v e r a l hundred km s _ 1 . B l u e s h i f t e d hydrogen and helium a b s o r p t i o n l i n e s with up to t h r e e components have been seen i n NGC 4151 (Anderson, 1974) with a v e l o c i t y spread of 900 km s _ 1 . The very broad wings of the permitted l i n e s i n most S e y f e r t g a l a x i e s i n d i c a t e v e l o c i t i e s of a few thousand km s _ 1 , i f they are due to mass motions. Some r e p r e s e n t a t i v e v e l o c i t i e s of n u c l e a r c l o u d s w i t h i n a high r e s o l u t i o n l i n e p r o f i l e are l i s t e d i n Table I. For comparison, the escape v e l o c i t y a t 1 pc from a c e n t r a l mass of 10 8 MQ i s 950 km s - 1 , and the sound speed i s 10 km s-\u00bb at 10* K. The l i s t of S e y f e r t o b j e c t s given by Vorontsov-Vel*yaminov and I v a n i s e v i c (1974) i n d i c a t e s Balmer l i n e wing v e l o c i t i e s ( f u l l width a t zero i n t e n s i t y ) of up to 10,000 km s - 1 . I t i s worth n o t i n g that the s i x t y g a l a x i e s l i s t e d t h e r e with measured Balmer l i n e widths do not show a double peaked d i s t r i b u t i o n a t 5000 and 11,000 km s~ 1 , but r a t h e r a broad d i s t r i b u t i o n of v e l o c i t i e s from zero to 10,000 km s - 1 , with a peak at 4000 -5000 km s - 1 . (Comparison of t h e i r measured widths with other p u b l i s h e d values f o r w e l l known o b j e c t s i n d i c a t e s t h a t the Vorontsov-Vel\u2022yaminov and I v a n s e v i c widths are lower by about Table I Maximum V e l o c i t y S e p a r a t i o n Between Components Of L i n e P r o f i l e s 11 | galaxy NGC 1068 | v e l o c i t y \u2022+-1300 km s - i NGC 1275 | 400 | Hc< ,NII I 3000 1 | d NGC 4151 | 800 | OIII 1 b,c NGC 5548 j 1500 1 Ho( 1 e NGC 7469 l 200 1 Hc( I f I 4329A J 2400 1 H ^ I h 3C 390.3 | 4100 | Hd #Hp,HV 1 3 a) Walker 1968 b) E i l e k et a l . , 1974 c) U l r i c h 1973 d) Burbidge and Burbidge 1965 e) Anderson 1971 f) Anderson 1973 g) Glaspey 1974 h) Disney 1973 j) Burbidge and Burbidge 1971 l i n e s NeIII,OIII a\",b source ten per c e n t . ) . Based on e a r l i e r , l e s s complete l i s t s of S e y f e r t l i n e widths, MacAlpine (1974) suggested t h a t such a double peaked d i s t r i b u t i o n e x i s t e d . I f t h i s were so, i t would tend to support tne Ptak and Stoner (1973) p a r t i c l e streaming model (see Chapter V I ) . The b l u e s h i f t e d a b s o r p t i o n l i n e s i n guasars show v e l o c i t i e s both w i t h i n the a b s o r p t i o n systems and r e l a t i v e to the emission system of up to an order of magnitude higher than the S e y f e r t v e l o c i t i e s . The quasar PKS 0237-23, f o r i n s t a n c e , shows a spread of Az=0.8 i n a b s o r p t i o n r e d s h i f t s , which corresponds to 12 &v=0.3c ( B a h c a l l e t a l . , 1968). Another o b j e c t , PHL 938, \\ (Burbidge e t a l . , 1968) shows a spread, Az=1.3, which corresponds to Av=0.5c. Schmidt (1970) g i v e s a f u l l review. \/ \/ 2. Heating Mechanisms \/ A c e n t r a l l y l o c a t e d i o n i z a t i o n source w i l l a c c e l e r a t e the gas or c l o u d s outwards. T h i s has been pointed out i n c o n n e c t i o n with S e y f e r t g a l a x i e s and quasars by Weymann (1970), Mushotzky, Solomon and S t r i t t m a t t e r (1972), and T a r t e r and McKee (1973), among o t h e r s . More d e t a i l e d models have been c o n s i d e r e d by Matthews (1974). T h i s c a l c u l a t i o n w i l l be d i s c u s s e d i n d e t a i l below, and compared to the case of cosmic ray a c c e l e r a t i o n . I f the c e n t r a l i o n i z i n g source i s an e x t e n s i o n of the o p t i c a l s y n c h r o t r o n continuum to X-ray e n e r g i e s (as has o f t e n been assumed), the i o n i z i n g l u m i n o s i t y can be found by d i r e c t e x t r a p o l a t i o n of the power law. The o p t i c a l continuum l u m i n o s i t y i s t y p i c a l l y 10* 3 ergs s _ 1 (see, f o r i n s t a n c e , Anderson, 1970). In quasars i t i s higher, about 10* 6 e r g s s~l (Wampler and Oke, 1967; Wampler, 1968). X-rays have been observed i n the d i r e c t i o n of two S e y f e r t s , NGC 1275 (Davidsen \u00a7t a l . , 1975) and NGC 4151 ( K e l l o g , 1973; Margon e t a l . , 1975) with l u m i n o s i t i e s of 3 x 10** and 10* 2 ergs s _ 1 r e s p e c t i v e l y . For NGC -4151 a turnover a t 3 keV i s suggested. The e m i s s i o n i n the d i r e c t i o n of NGC 1275 i n c l u d e s the e n t i r e Perseus c l u s t e r . One QSO, 3C 273, shows an X-ray l u m i n o s i t y of 4 x 10* 6 ergs s~1 (Bowyer e t a l . , 1970). These o b s e r v a t i o n s may i n d i c a t e a separate X-ray source that i s not an e x t e n s i o n of the o p t i c a l 13 s o u r c e . In t h e o r e t i c a l c a l c u l a t i o n s , Matthews (1974) has taken 10 4* ergs s _ l as the i o n i z i n g photon l u m i n o s i t y f o r S e y f e r t n u c l e i and 1 0 4 6 ergs s~l f o r quasars. I f the i o n i z a t i o n i s due to e n e r g e t i c p a r t i c l e s , a measure of the p a r t i c l e f l u x based on observable q u a n t i t i e s i s h i g h l y model dependent. The d e t a i l e d d i s c u s s i o n of t h i s i s l e n g t h y , and i s postponed to the f o l l o w i n g s e c t i o n . The p a r t i c l e energy c o n t a i n e d i n the \" t y p i c a l \" a c t i v e o b j e c t i s e s t i m a t e d to range from 1 0 s 3 t o 1 0 5 7 e r g s , with unavoidable u n c e r t a i n t i e s of a couple o r d e r s of magnitude, f o r models of S e y f e r t n u c l e i and quasars. An a l t e r n a t i v e dynamical model i s proposed by Wolfe (1974). In h i s model a s u p e r s o n i c g a l a c t i c wind, a k i n to the s o l a r wind s o l u t i o n s by Parker (1965), accounts f o r the observed v e l o c i t i e s . The e n e r g y \/ i o n i z a t i o n sources are not e x p l i c i t l y c o n s i d e r e d but the c o n s t a n t temperature of 10 6 K which he assumes throughout the wind probably r e g u i r e s an extended, n o n - c e n t r a l heat source. P a r k e r ' s wind model does not r e q u i r e an i s o t h e r m a l gas, but does r e q u i r e t h a t T (r) decrease l e s s r a p i d l y than r - 1 . As shown below, the gas must be very hot, a t l e a s t 10 6 K, to reach the observed v e l o c i t i e s with the s u p e r s o n i c wind model. T h i s model t r e a t s a c o n t i n u o u s gas flow. Wolfe suggests, however, t h a t thermal i n s t a b i l i t y may l e a d to c o o l e r , dense clou d s c o - e x i s t i n g with the wind. Extended, n o n - l o c a l heating f o r the OEH would probably come from s t e l l a r c o l l i s i o n s and bow shocks, or c o l l i s i o n s of d i s c r e t e c l o u d s . Cloud c o l l i s i o n s have been mentioned i n c o n n e c t i o n with quasars by D a l t a b u i t and Cox (1972). For 14 S e y f e r t g a l a x i e s , t h i s mechanism has been suggested by Osterbrock and Parker (1965) and by Oke and Sargent (1968). However, the source of the c l o u d k i n e t i c energy which i s transformed i n t o gas h e a t i n g remains u n s p e c i f i e d . Star c o l l i s i o n s i n a dense s t e l l a r nucleus have been c o n s i d e r e d by S p i t z e r and Saslaw (1966), S p i t z e r and Stone (1967), and more r e c e n t l y by Shara and Shaviv (1974). In order f o r the f u l l energy output of S e y f e r t g a l a x i e s to be thus e x p l a i n e d , (Shara and Shaviv d i s c u s s energy r e l e a s e through c o l l i s i o n - i n d u c e d novae i n white dwarfs) an u n u s u a l l y dense s t e l l a r system i s needed - over 1 0 1 0 MQ w i t h i n 1 pc of the c e n t e r . A d e t a i l e d model must, of c o u r s e , a l s o c o n s i d e r the e f f i c i e n c y of t r a n s f o r m i n g the k i n e t i c energy to thermal energy of the gas, which w i l l depend on the o p a c i t y of the r a d i a t i o n produced i n the shocks. Another steady wind model which does not r e q u i r e an extended hot gas has been proposed by I p a v i c h (1975). In t h i s model, the i n t e r a c t i o n of e n e r g e t i c p a r t i c l e s with a random magnetic f i e l d of about 10-* gauss w i l l a c c e l e r a t e a c o l d gas up t o 1500 km s ~ l . 3. C e n t r a l Mass And Source L i f e t i m e The c e n t r a l mass i n the S e y f e r t nucleus i s hard to o b t a i n o b s e r v a t i o n a l l y . Oort (1971) has used microwave o b s e r v a t i o n s to measure the s t a r d e n s i t y i n the very i n n e r r e g i o n s of our galaxy and M31, f i n d i n g a d i s t r i b u t i o n f o r the i n n e r few pc, M (r) = 4 x 10 6r Mg,, where r i s i n pc, with a c e n t r a l mass of 15 3 x 10^ M g i n s i d e 0-1 pc. For N G C 1068, Walker (1968) found M = 3 x 10\u00ab M & w i t h i n 2000 pc of the c e n t e r ; f o r N G C 3227 Rubin and Ford (1968) found 3 to 4 x 10* H c i n s i d e 620 pc; f o r N G C 7469 Anderson (1973) found about 10 9 ft& i n s i d e 400 pc. Sanders (1970), c o n s i d e r i n g c l o u d motions, estimated the c e n t r a l mass of N G C 4151 as between 1-1 and 3.5 x 10 9 M 0 i n s i d e 4.5 pc. Improved S t r a t o s c o p e I I photographs of N G C 4151 ( S c h w a r z s c h i l d , 1973) show a nu c l e a r diameter of under 7 pc, c o n t a i n i n g an estimated c e n t r a l mass of 4 x 10 9 M ^ . Anderson (1973), based on the smoothness of the i n n e r p a r t of the r o t a t i o n curve of N G C 7469, concludes there i s , however, no c e n t r a l p o i n t mass g r e a t e r than 108 i n that galaxy. The higher of the nu c l e a r v e l o c i t i e s i n d i c a t e d by the l i n e widths and l i n e p r o f i l e s t r u c t u r e s are g r e a t e r than the escape v e l o c i t y f o r the r e g i o n ; f o r a c e n t r a l mass of 10 8 H Q, the escape v e l o c i t y i s 950\/>Jr^ km s ~ 1 i f r ^ c i s the d i s t a n c e i n pc. T h e r e f o r e , the phenomena we are seeing may be q u i t e s h o r t l i v e d . A c l o u d t r a v e l l i n g a t 1000 km s - 1 w i l l c r o s s 10 pc i n 10* years. The sound t r a v e l time f o r the same re g i o n a t 10* K, i s 5 x 10 s years. The mass outflow i n v o l v e d i n Wolfe's (1974) steady s t a t e model i s 20 H Q per year; t h i s i m p l i e s a l i f e t i m e l e s s than 10 7 years, i f a l l the n u c l e a r mass feeds the wind. T h i s f i g u r e i s j u s t s l i g h t l y higher than the mass l o s s i n d i c a t e d by Walker's (1968) measurements of N G C 1063. Since the S e y f e r t phenomenon i s s t a t i s t i c a l l y estimated to l a s t 10 8 years ( W o l t j e r , 1959), some means of renewal of these processes i s necessary. E s t i m a t e s of the mass l o s s r a t e by normal s t a r s (see Sanders and Prendergast, 1974), perhaps augmented by a high c o l l i s i o n r a t e 16 such as S c h w a r z s c h i l d (1973) p r e d i c t s i n the nucleus of NGC 4151, seem t o account f o r the above f i g u r e s . ( T h i s i s d i s c u s s e d i n Chapter VI.) On the oth e r hand, Sanders and Prendergast (1974) have shown that a s i n g l e e x p l o s i v e event ( r e q u i r i n g 3 x 10 5\u00ab ergs and 10 s Me e j e c t e d , i n a numerical model of our galaxy) i n a r o t a t i n g g a l a c t i c d i s k w i l l produce an o s c i l l a t i n g r i n g . T h i s seems t o l a s t through s e v e r a l o s c i l l a t i o n s , much l o n g e r than i t s expected \" c r o s s i n g time\". Such a mechanism, based on the i n t e r a c t i o n of the n u c l e a r gas with the i n n e r g a l a c t i c plane, may reduce the mass'loss r a t e and the replenishment necessary. The \" t y p i c a l \" model d e s c r i b e d here i s summarized i n Table I I , f o r l a t e r r e f e r e n c e . I f the parameters are observed to be s i g n i f i c a n t l y d i f f e r e n t f o r S e y f e r t n u c l e i than f o r quasars, the quasar value i s given i n the second l i n e . E s t i m a t e s Of C e n t r a l Source E n e r g e t i c s I f the nonthermal l u m i n o s i t y i n some wavelength band of the a c t i v e nucleus i s e l e c t r o n s y n c h r o t r o n r a d i a t i o n , and i f the othe r source parameters are s p e c i f i e d , then t h a t l u m i n o s i t y depends uniquely on the t o t a l p a r t i c l e spectrum. In p r a c t i c e , these other parameters -- p a r t i c l e energy, magnetic f i e l d , p r o t o n \/ e l e c t r o n energy r a t i o , source geometry --'cannot be uniquely determined o b s e r v a t i o n a l l y . S i n c e many a c t i v e o b j e c t s emit i n the r a d i o and o p t i c a l r e g i o n s , and a few i n the IB and X-ray as w e l l , e f f o r t s have been made to combine some of these components i n t o a c a n o n i c a l model. As an example, Fi g u r e 0 shows the conti n u o u s s p e c t r a of 17 F i g u r e 0. Continuum o b s e r v a t i o n s of the two well-observed S e y f e r t n u c l e i are shown from the r a d i o to the X-ray. NGC 1068 i s from S h i e l d s and Oke, 1975, and from Jones and S t e i n , 1975. NGC 4151 i s from B a i t y e t a l . , 1975. 18 F i q u r e 0. S e y f e r t Nuclear S p e c t r a 1? T a b l e I I Parameters Of A Standard A c t i v e Nucleus r T \/ \/ - \u2022\u2022\u2022 i | Extent ( v a r i a b i l i t y ) | 0.1 pc | --(VLS I , r a d i o source) | 0.1 pc \/ I \u2014 ( o p t i c a l l y resolved) | 1-10 pc | C e n t r a l Mass | ( S e y f e r t s only) I 108 M o | E m i t t i n g Mass | (Balmer l i n e s ) I 102 M o - 103 M @ | Lx ( h ^ ~ 1-10 keV) | 1 0 * Z - 1 0 * * | 10* 6 ergs ergs s- 1 s - i | J L(opt + UV) | 1 0 * 3 - 1 0 * * | 10* 6 ergs ergs s _ 1 s - i | 1 L l R - 1 0 1 3 U z> | 10*5-10*6 | 10* 7 ergs ergs s - i s - i | | 1038 - 1 0*1 | 10* 5 ergs ergs s - i s - i I | 1 0 s 3 ergs \\ 1054-1057 ergs L , . .. _. 1 1 NGC 1068 and NGC 4151. Demoulin and Burbidge (1968) c o n s i d e r the o p t i c a l continuum, a s c r i b e i t t o e l e c t r o n s y n c h r o t r o n , and assume e q u i p a r t i t i o n of e l e c t r o n and magnetic f i e l d e n e r g i e s . Bergeron and S a l p e t e r (1973) assume the IR f l u x (peaking about 1 0 1 2 Hz) to be s y n c h r o t r o n , and the X-ray peak to be due to i n v e r s e Compton s c a t t e r i n g of the IR photons. Jones, O ' D e l l and S t e i n (1974a,b) and Burbidge, Jones and O' D e l l (1974), c o l l e c t i v e l y known as JCES, assume the r a d i o e mission t o be s y n c h r o t r o n , and the o p t i c a l emission to r e s u l t from i n v e r s e Compton s c a t t e r i n g of the r a d i o a m i s s i o n . 20 One important r e s t r i c t i o n i n i d e n t i f y i n g the s y n c h r o t r o n - s o u r c e p a r t i c l e s with the i o n i z i n g mechanism f o r the o p t i c a l gas i s the s m a l l s c a l e of the gas, i m p l i e d by the r a p i d v a r i a b i l i t y - The s i z e s of the r a d i o sources of the JOBS models, as measured by VLBI, are c o n s i s t e n t with the t h e o r e t i c a l e s t i m a t e s and with t h e \u2022 v a r i a b i l i t y . The IE s y n c h r o t r o n source i n a c t i v e n u c l e i i s c a l c u l a t e d at a s i z e of under 1 pc, but o b s e r v a t i o n s are i n c o n f l i c t as to i t s s i z e - Reports of v a r i a b i l i t y from 5 t o 25 microns (Kleinmann and Low, 1970, Rieke and Low, 1972) are d i s p u t e d (Morrison and Simon, 1973; S t e i n , G i l l e t t and M e r r i l , 1974). Neugebauer, Garmine, Reike and Low (1971) r e p o r t r e s o l v i n g the n u c l e i of NGC 1068 at 1.6 and 2.2 microns. They suggest a p o i n t source dominating at l o n g e r wavelengths plus an extended source as l a r g e as 100 pc a t 1-2 microns. An a l t e r n a t e e x p l a n a t i o n of the IR emission i s thermal emission due t o dust g r a i n s . Bergeron and S a l p e t e r show t h a t a source at l e a s t 100 pc a c r o s s i s needed t o reach the high f l u x e s seen i n some o b j e c t s , up to 3 x 10* 6 ergs s~l at 10* 3 Hz i n NGC 1068 and NGC 4151 a c c o r d i n g to Low (1971). Recent s p e c t r a of NGC 1068 by Jameson, Longraire, McLinn and woolf (1974) resemble the d u s t l i k e s p e c t r a of some pl a n e t a r y nebulae. The measurement of reddening i n s e v e r a l S e y f e r t n u c l e i by Wampler (1968) a l s o i n d i c a t e s the presence of dust. Jones and S t e i n (1975) review a l l of the IR o b s e r v a t i o n s of NGC 1068 and conclude that thermal dust models best s a t i s f y the data. The necessary parameters f o r IR s y n c h r o t r o n models are d e r i v e d by Bergeron and S a l p e t e r . The s e l f a b s o r p t i o n turnover r e q u i r e s a magnetic f i e l d of 10 to 100 gauss.- T h i s i s much 21 g r e a t e r than the e q u i p a r t i t i o n f i e l d , which i s t y p i c a l l y 100 to 1000 m i l l i g a u s s , i m p l y i n g the magnetic f i e l d dominates the gas dynamics. A l s o , the p a r t i c l e energy i s r e l a t i v e l y low, 10* 8 ergs or so, and the i n d i v i d u a l p a r t i c l e l i f e t i m e only 10 3 seconds, so constant replenishment i s needed. F i n a l l y , Knacke and Capps (1974) d e r i v e a magnetic f i e l d of 100 t n i l l i g a u s s from Faraday r o t a t i o n measures. T h i s agrees with the dust model. On the other hand, a s c r i b i n g the r a d i o source to e l e c t r o n s y n c h r o t r o n emission, JOBS produce models with magnetic f i e l d s a f a c t o r of ten below the e q u i p a r t i t i o n v a l u e . T h i s i m p l i e s a p a r t i c l e dominated dynamics. T h e i r t o t a l e l e c t r o n e n e r g i e s range from 1 0 5 3 to 1 0 5 7 ergs i n t h e i r models of s p e c i f i c S e y f e r t n u c l e i and quasars. The r a t i o of p r o t o n \/ e l e c t r o n e n e r g i e s depends on the unknown a c c e l e r a t i o n mechanism, and i s taken by Demoulin and Burbidge to be i n the range 1 to 100. For comparison, e q u i p a r t i t i o n e s t i m a t e s using n u c l e a r s i z e s compatible with the observed s h o r t term v a r i a b i l i t y p r e d i c t 1 0 5 2 to 1 0 5 b ergs i n t o t a l p a r t i c l e energy i n a c t i v e n u c l e i . JOBS emphasize the u n c e r t a i n t i e s i n these energy e s t i m a t e s . The low energy c u t o f f of the p a r t i c l e spectrum as well as the p r o t o n \/ e l e c t r o n energy r a t i o must be assumed, and p h y s i c a l l y r easonable v a r i a t i o n s i n these parameters can a f f e c t the t o t a l energy by orders of magnitude. Estimates of the,magnetic f i e l d from d i f f e r e n t observed parameters are i n c o n s i s t e n t w i t h i n a s i n g l e o b j e c t , which r e f l e c t o b s e r v a t i o n a l e r r o r s or complexity of the source. The geometry of the source, or a n i s o t r o p y of the p a r t i c l e streaming, a l s o s t r o n g l y a f f e c t s the d e r i v e d parameters. 22 In view of the u n c e r t a i n t i e s even w i t h i n the r a d i o - s y n c h r o t r o n model \u2014 which seems more t e n a b l e than the IR s y n c h r o t r o n model \u2014 no d e f i n i t e value f o r the cosmic ray i o n z i n g f l u x , or the t o t a l cosmic ray energy, can be s p e c i f i e d . For purposes of the c a l c u l a t i o n s i n t h i s t h e s i s , a \" t y p i c a l \" r a t h e r than a s p e c i f i c model of S e y f e r t n u c l e i or quasars i s d e s i r e d , and any cosmic ray f l u x c o n s i s t e n t with the e n e r g i e s gi v e n by JCBS or by e g u i p a r t i t i o n w i l l be c o n s i d e r e d a c c e p t a b l e . A p a r t i c l e dominated dynamics w i l l a l s o be assumed. A c c e l e r a t i o n Of Gas Clouds By A C e n t r a l Source A t t e n t i o n has been given i n the l i t e r a t u r e t o the dynamical e f f e c t s of the i o n i z a t i o n sources proposed f o r S e y f e r t n u c l e i and quasars. Emphasis has been on the v e l o c i t i e s a t t a i n a b l e by ra-diation pressure on d i s c r e t e c l o u d s , with i n t e n t to e x p l a i n the l a r g e r e l a t i v e v e l o c i t i e s seen i n these o b j e c t s . The observed v e l o c i t i e s range from 100 km s - 1 to 0.5c, as mentioned above. Weymann (1973) has reviewed the s u b j e c t . He p o i n t s out t h a t r e s o n a n c e - l i n e a c c e l e r a t i o n i s not l i k e l y to produce high enough v e l o c i t i e s when c o n s i d e r e d r i g o r o u s l y . A c o n t i n u o u s , steady supersonic-wind flow i s a l s o u n l i k e l y to reach the observed v e l o c i t i e s . I f the wind i s at the temperatures i n d i c a t e d by the f o r b i d d e n l i n e s , about 10* K, then the q u a n t i t y L^\/GH must i n c r e a s e d r a s t i c a l l y past the s o n i c p o i n t , where L i s the c e n t r a l source l u m i n o s i t y , ^ i s the c r o s s s e c t i o n between the quanta from the c e n t r a l source and the ambient gas, and M i s the c e n t r a l mass. T h i s r a p i d change i n L = 9 x I P 2 * L