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Abstract Motivated by recent successes in linking the kinetic power of relativistic jets in active galactic nu- clei (AGN) to the low-frequency, isotropic lobe emission, I have re-examined the blazar and radio- loud AGN unification scheme through careful analysis of the four parameters we believe to be fundamental in producing a particular jet spectral energy distribution (SED): the kinetic power, ac- cretion power, accretion mode, and orientation. In particular, I have compiled a multi-wavelength database for hundreds of jet SEDs in order to characterize the jet spectrum by the synchrotron peak output, and have conducted an analysis of the steep lobe emission in blazars in order to deter- mine the intrinsic jet power. This study of the link between power and isotropic emission is likely to have a wider applicability to other types or relativistic jet phenomena, such as microquasars. Based on a well-characterized sample of over 200 sources, I suggest a new unification scheme for radio-loud AGN (Meyer et al. 2011) which compliments evidence that a transition in jet power at a few percent of the Eddington luminosity produces two types of relativistic jet (Ghisellini, et al., 2009). The ‘broken power sequence’ addresses a series of recent findings severely at odds with the previous unification scheme. This scheme makes many testable predictions which will can be addressed with a larger body of data, including a way to determine whether the coupling between accretion and jet power is the currently presumed one-to-one correspondence, or whether accretion power forms an upper bound, as very recent observations suggest (Fernandes et al. 2011). This work is a first step toward a unified understanding of the relativistic jets found in radio-loud active galactic nuclei (AGN) and their connection to accretion onto the super-massive black holes from which they emanate. Acknowledgments I would like to dedicate this thesis to my parents, John and Colette Meyer, who made many sacrifices so that I might receive the best education pos- sible. Without their continuous emotional and financial support, practical advice, and sincere encouragement I simply would not have completed a Ph.D. I also wish to acknowledge Roman Natoli and the many friends that stood by me in the toughest years of graduate school. A special ac- knowledgment must be reserved for Markos Georganopoulos, who pro- vided mentoring, ideas, and encouragement at a very crucial time, and without whom this thesis would not have been written. Finally I wish to thank my advisor Giovanni Fossati for bringing me to the world of high- energy astrophysics, and mentoring me in the first stages of my career as a physicist. Contents 1 Introduction 2 1.1 A Very Brief History of Active Galactic Nuclei . 2 1.2 TheActiveGalaxy:ASketch .. .. .. ... .. .. .. .. .. ... 5 1.2.1 AGNTaxonomy.......................... 6 1.2.2 At the Center of it All: the Super-Massive Black Hole . 14 1.2.3 Accretion Regimes . 20 1.3 Jets: Emission, Modeling, and Observations . 24 1.3.1 SynchrotronRadiation . 24 1.3.2 Synchrotron emission in radio-loud AGN . 28 1.3.3 Relativistically Beaming and Superluminal Motion . 30 1.3.4 Inverse Compton Scattering . 35 1.3.5 JetModels............................. 37 1.3.6 Radio Observations of Jets . 41 1.3.7 Infrared to UV Observations of Jets . 44 1.4 Radio-loud AGN Unification and Its Problems . 46 1.4.1 The Orientation Paradigm . 46 1.4.2 The Demographics of Blazars and the Sequence . 48 1.4.3 Unification Breaks Down . 58 2 The Blazar Envelope 60 2.1 Introduction................................ 60 2.2 Methods.................................. 62 2.2.1 TheBlazarSample ........................ 63 2.2.2 The Radio Galaxy Sample . 74 2.3 Results................................... 76 2.3.1 The Blazar Envelope . 76 2.3.2 Estimating Relative Beaming with Radio Core Dominance . 79 2.4 DISCUSSION............................... 83 2 2.4.1 The Blazar Envelope . 83 3 The Relativistic Jet Dichotomy and Unification 89 3.1 Methods.................................. 90 3.1.1 An Updated Blazar Sample . 92 3.1.2 Characterizing the IC peak . 96 3.1.3 The Mass of the Central Black Hole . 99 3.2 ACriticalAccretionRate?. 99 3.3 Exploring the Broken Sequence Hypothesis . 103 3.4 Evidence for ‘Fake’ BL Lac Objects . 106 4 Collective Evidence for External Compton Emission in High-Power Jets 109 4.1 Introduction ............................... 109 4.2 Methods.................................. 111 4.2.1 Gamma-ray Power Measured by Fermi ............. 111 4.2.2 TheOVROsub-sample. 113 4.2.3 Emission Mechanisms and Their Beaming Patterns . 114 4.3 Results................................... 116 4.3.1 The Blazar Dichotomy at High Energies . 116 4.3.2 The Importance of Jet Kinetic Power at High Energies . 118 4.3.3 The Compton Dominance in Fermi Blazars . 120 4.3.4 Possible ramifications for velocity gradient models . 123 4.3.5 The Test of Superluminal Motions . 124 4.3.6 Why is EC Only Apparent in Powerful Jets? . 126 5 Conclusions and Implications for the AGN Paradigm 128 5.1 Summary ................................. 128 5.2 Application to Previous Challenges . 130 5.3 FutureWork................................ 131 5.4 TheGreaterContext . 132 Appendices 151 A Blazar Surveys and Samples 151 A.1 The1-JanskySample........................... 151 A.2 The2-degreefieldQSOSurveyBLLacSample . 151 A.3 The 2-Jansky Sample of Wall & Peacock . 152 A.4 The CRATES Sample .......................... 152 A.5 The CLASS BlazarSample ....................... 153 A.6 The DXRBS Survey ........................... 153 A.7 The EGRET BlazarSample ....................... 154 A.8 The EMSS SlewSurveyofBLLacs . 154 A.9 The HRX Sample............................. 155 A.10 The Parkes Quarter-Jansky Flat Spectrum Sample . 155 A.11 The REX Survey ............................. 155 A.12 The ROXA Catalog............................ 156 A.13 The RGB Sample............................. 156 A.14 The EMSS Medium-Sensitivity Survey of BL Lacs . 157 A.15 The SDSS Flat-SpectrumSample . 157 B Phenomenological Blazar SED model 159 C Radio Core Dominance 160 D Evaluation of Selection Effects in the Blazar Envelope 161 D.1 BiasintheRadioSelection. 161 D.2 UpperLimits ............................... 161 D.3 The Effect of Missing Redshifts: Revisiting the High-Power, High-Peak zone .................................... 163 D.4 RemainingSample ............................ 166 E A Discussion of High-Power, Gamma-ray Hard Blazars 167 F Data Tables 170 List of Figures 1.1 The Unusual Spectra of Active Galaxies . 3 1.2 Nearby Radio Galaxy Centaurus A . 4 1.3 TheUnifiedModelforAGN ....................... 7 1.4 Host Galaxies of Radio Quiet AGN . 8 1.5 AGNTaxonomy.............................. 9 1.6 Fanaroff and Riley Type I and II Radio Galaxies . 10 1.7 FR I/II radio luminosity as a function of host magnitude . 11 1.8 The M − σ massrelationforSMBH. 17 1.9 SMBH Mass from Single-Epoch Spectroscopy . 19 1.10 The Radio to Gamma-ray Spectral Energy Distribution of a Blazar . 25 1.11 Beamed Emission from a Relativistic Particle . 26 1.12 TheSynchrotronSpectrum. 27 1.13 The Steep Spectrum of Radio Galaxy Lobes . 29 1.14 TheFlatSpectrumofBlazars . 30 1.15 The Doppler Factor versus Orientation Angle . 32 1.16 Superluminal Motion and Apparent Jet Speed . 33 1.17 The Effect of Relativistic Beaming on the SED . 34 1.18 SED Fitting with a One-zone Leptonic Jet Model . 38 1.19 Velocity Gradient Jet Model SEDs . 40 1.20 RadioObservationsofJets. 43 1.21 Host Galaxy and Accretion Disk contribution to Blazar Spectra ... 44 1.22 Dilution of Calcium Break by Nonthermal Jet Emission & Optical Jet EmissioninFRI ............................. 45 1.23 TheBlazarSequence ........................... 49 1.24 TheBlazarSequence ........................... 50 1.25 TheBlazarSequence ........................... 53 1.26 The DXRBS and the Blazar Sequence . 54 1.27 Determining SED shape with Spectral Indices . 55 5 1.28 TheCLASSBlazarsSEDProperties . 56 2.1 A Mono-parametric Blazar Envelope . 61 2.2 Jet Kinetic Power Scaling from X-ray Cavities . 67 2.3 The Isotropic, Extended Radio Emission in Blazars and Radio Galaxies 69 2.4 Crossing Frequency of Jet Dominance versus Core Dominance . 71 2.5 Visual Inspection of Blazar SEDs . 73 2.6 The New Blazar Envelope . 78 2.7 Core Dominance versus Synchrotron Peak Luminosity . 81 2.8 Core Dominance versus Synchrotron Peak Frequency . 82 2.9 A Dichotomy in the Blazar Envelope . 86 3.1 Frequency Ranges and Sensitivities for WISE, Planck, GALEX, GMRT, and Fermi.................................. 91 3.2 InverseComptonSEDsandModelFits . 97 3.3 Estimating Fermi Upper Limits for Nondetections . 98 3.4 The Distribution of Black Hole Masses in the Envelope . 101 3.5 Histogram of Lkin /LEdd for strong and weak jets . 102 3.6 The Radio Galaxy and Blazar Divide in Accretion Efficiency . 103 3.7 Testing the Broken Power Sequence . 104 3.8 Testing the Strong-jet and Weak-jet Sequences . 105 3.9 Distribution of BL Lacs with Beaming Factor . 107 4.1 External Compton Beaming Patterns with Unequal Γ . 116 4.2 The High-Energy Blazar Envelope . 118 4.3 Inverse Compton Peak Luminosity versus Radio Core Dominance . 119 4.4 Compton Dominance versus Radio Core Dominance . 121 4.5 Compton Dominance versus Radio Core Dominance with SA slope . 123 4.6 An Examination of βapp with Core and Compton Dominance . 125 5.1 Statistical Checks on the Envelope . 162 5.2 A Simulation of the Blazar Sequence . 164 5.3 Four Candidate High-Power ISP Blazars . 165 5.4 Spectral Indices of Rejected Sources . 167 5.5 Photon Indices and Significance of Fermi Sources lacking Redshifts . 168 5.6 The IC Lγ − Γγ plane for Fermi Sources Lacking Redshifts . 169 List of Tables 2.1 BlazarSamples .............................. 64 2.2 Overview of Strong and Weak Jet Classes . 87 3.1 Planck Frequencies and Number of Detections in the Updated Sample 94 4.1 Predicted Correlation Slopes* for Beamed Gamma-ray Emission . 115 5.1 TEX Combined Blazar Source List . 171 5.1 TEX Combined Blazar Source List .