From the Outer Heliosphere to the Local Bubble (eBook)

Foreword 8
Dedication to Dr. George Gloeckler 11
The Solar Wind in the Outer Heliosphere 13
Introduction 13
Solar Wind Evolution 15
Effects of the Neutral CHISM on the Solar Wind 17
The Termination Shock 17
Anomalous Cosmic Rays 23
Summary 24
Acknowledgements 24
References 24
Constraints on the Structure of the Heliospheric Interface Based on Lyalpha Absorption Spectra 27
Introduction 27
The Heliospheric Absorption Detections 28
Absorption Dependence on the ISM Magnetic Field 30
Extended Tail Models 33
Acknowledgements 36
References 36
Influence of the Interstellar Magnetic Field and Neutrals on the Shape of the Outer Heliosphere 37
Introduction 38
Heliospheric Asymmetry Induced by the ISMF 39
Sources of the 2-3 kHz radio emission 45
Conclusions 46
Acknowledgements 47
References 47
Confronting Observations and Modeling: The Role of the Interstellar Magnetic Field in Voyager 1 and 2 Asymmetries 49
Introduction 50
Observational Evidences for Asymmetries 52
Interstellar Magnetic Field Direction 53
Model 54
Squashed Solar System: Global Asymmetries 54
Discussion and Conclusions 58
Neutral H Atoms 58
Solar Cycle 59
Energetic-Particle Mediated Shock 59
Acknowledgements 59
References 60
The Dynamic Heliosphere: Outstanding Issues 62
Introduction 63
On the Origin of Anomalous Cosmic Rays 64
Observations of ACRs Near the Termination Shock 64
Classic (Drift) Paradigm 66
Shock Geometry and Longitudinal Effects 67
Dynamical Effects 68
Acceleration in the Heliosheath 69
Variability of the Termination Shock Region and Heliosheath: Solar Cycle and Transient Effects 70
Propagation of a Solar Wind Velocity Pulse through the Heliosphere 71
Instability of the Heliopause 75
The Effects of the Solar Activity Cycle 75
Connecting ENAs with Lyalpha Absorption Measurements 77
A Comparison between the Heliosheath and Other Sheaths in Space 80
Ion Distributions 81
Sheath Size and Structure 82
Waves 82
Outlook: Heliosheath Thickness and Processes at the Heliopause 83
Estimating the Thickness of the Heliosheath 83
Energetic Particles at the Heliopause 84
Conclusions 85
Acknowledgements 85
References 85
The Heliospheric Magnetic Field and Its Extension to the Inner Heliosheath 89
The Global Heliospheric Magnetic Field: the Parker Formulation 90
Deviations from the Parker Model of the Heliospheric Magnetic Field 91
Structures in the Heliospheric Magnetic Field: Solar Cycle Effects 93
The Solar Corona, the Heliospheric Magnetic Field and the Heliospheric Current Sheet 94
Corotating Interaction Regions 98
``Interplanetary'' Coronal Mass Ejections through the Heliosphere 102
The Magnetic Field in the Heliosheath 105
The Magnetic-Field Sector Structure in the Heliosheath 106
Application to Observations 108
Magnetic Fluctuations in the Heliosheath 109
Summary 110
Acknowledgements 111
References 111
Pickup Ion Acceleration at the Termination Shock and in the Heliosheath 115
Introduction 115
Modeling Anisotropic Distributions: Focused Transport 117
Distribution Functions of Energetic Particles Near a Quasi-Perpendicular Shock 119
Pitch-Angle Distributions 122
The Heliosheath 124
Conclusions 126
Acknowledgements 127
References 127
ENA Imaging of the Inner Heliosheath-Preparing for the Interstellar Boundary Explorer (IBEX) 129
Introduction 129
Early Efforts to Observe ENAs from the Heliosheath 130
The Interstellar Boundary Explorer 132
Discussion 138
Acknowledgements 139
References 141
Local Interstellar Parameters as They Are Inferred from Analysis of Observations Inside the Heliosphere 143
Introduction 143
Observations from Inside the Heliosphere 145
Multi-Component Models of the Global Heliosphere 147
CHISM Parameters Inferred from Data and Theory 148
Conclusions and Perspectives 152
Acknowledgements 153
References 153
Interplanetary Lyman alpha Observations: Intensities from Voyagers and Line Profiles from HST/STIS 155
Introduction 155
Intensities in the Outer Heliosphere 156
Heliosphere Scans with Voyager-UVS 156
Radial Variation of the Upwind Intensity 159
Line Profiles in the Inner Heliosphere 162
Conclusion and Discussion 163
References 165
Composition of Interstellar Neutrals and the Origin of Anomalous Cosmic Rays 167
Introduction 168
Interstellar Neutral Densities at 90-100 AU 169
Abundance of Interstellar Neutrals at the TS from Pickup Ions 169
Tails and ACRs in the Inner Heliosheath 172
ACRs in the Outer Heliosheath 175
Abundance of Interstellar Neutrals from Tails and ACRs 175
Discussion and Summary 177
Acknowledgements 178
References 178
Neutral H Density at the Termination Shock: A Consolidation of Recent Results 180
Introduction 180
Neutral Gas Density from Pickup Ion Observations 181
Past Attempts to Derive the Density at the Termination Shock 181
Modeling Uncertainties in Pickup Ion Interpretations 182
Robust Method to Determine the Density at the Termination Shock 184
Simplified analytic derivation 185
Simulations of the H PUI Production Rate at Ulysses 186
Determination of Hydrogen Density at the Termination Shock 188
Consolidation of the Interstellar H Density 188
Density of H at the Termination Shock 188
Extrapolating the Termination Shock Density to the CHISM 189
Conclusions 191
Acknowledgements 191
References 191
Is the Sun Embedded in a Typical Interstellar Cloud? 194
Introduction 194
Galactic Environment of the Sun 195
Heliospheric ISM 195
Kinematics and Temperatures of Very Local ISM versus Warm Interstellar Gas 197
Partially Ionized Gas and the Interstellar Radiation Field 200
Chemical Composition of the ISM at the Sun 202
Interstellar Magnetic Field at the Solar Location 203
Conclusions 204
Acknowledgements 205
References 206
Pressure and Ionization Balances in the Circum-Heliospheric Interstellar Medium and the Local Bubble 208
Introduction: The Pressure Problem 208
Development of the Conventional View of the Local Bubble (LB) 209
The Circum-Heliospheric Interstellar Medium (CHISM) 210
Attempted Solutions that Seem to Fail 210
An imbalance is acceptable 210
Magnetic support 210
Turbulent support 211
Early Indications of Trouble with the X-ray Background Measurements 211
How Else to Measure the Pressure in the LB? 212
The Fine-Structure Excitation of Neutral Carbon 212
EUV Diffuse Background 213
Cloud Lifetimes 213
Pressure Balance Between the LB and Galactic Disk 214
Ionization State of the CHISM 214
Initial Findings 214
Incomplete Recombination? 215
Diffuse Hard Photoionization Flux 215
Acknowledgements 217
References 217
The Solar Wind Charge-eXchange Contribution to the Local Soft X-ray Background 220
Introduction 221
SWCX Model Description 222
SWCX in the 3/4 keV Band 223
Stationary Model Maps 223
Dynamic Simulations 225
The Case of the MBM 12 Suzaku Observation of February 2006 225
Summary of Shadowing Observations 227
SWCX in the 1/4 keV Band 228
Simulations 229
Model-Data Comparison 229
Wisconsin Sounding Rocket Survey 230
The ROSAT Survey 231
Discussion 232
Acknowledgements 233
References 233
Revising the Local Bubble Model due to Solar Wind Charge Exchange X-ray Emission 234
Introduction 234
The Historical Local Bubble Model 235
Charge Exchange in the Solar System 236
Solar Wind Charge Exchange X-rays 236
Solar Wind Charge Exchange O VI 237
Is There a Hot Local Bubble After All? 238
Revising the Local Bubble 240
How We Can Make Progress 241
Acknowledgements 241
References 241
Warm and Hot Gas in the Local ISM 243
Introduction 243
Local Warm Gas 245
Density and Temperature 245
Local Ionization 245
Velocity Structure 246
Element Abundances 248
The Detectability of Hot Gas in the Local Cavity 248
Local C IV and Si IV Absorption 248
Local O VI Absorption 249
The Local Chimney Connection 252
Future Observations 253
Acknowledgements 253
References 253
What Can Be Learned from X-ray Spectroscopy Concerning Hot Gas in the Local Bubble and Charge Exchange Processes? 255
Introduction 255
A Little History-Instrumentation 256
Spectrum Röntgen Gamma 258
What Can Be Learned? 259
Random Thoughts 261
Summary 262
Acknowledgements 264
References 264
What Physical Processes Drive the Interstellar Medium in the Local Bubble? 265
Introduction 266
Modeling the ISM and the Local Bubble 266
A Supernova Driven ISM Model 267
Results on the General ISM 268
Modeling the Local Bubble 271
Results on the Local Bubble 273
Comparison with Observations 275
Summary and Conclusions 277
Acknowledgements 277
References 277
Plasma Turbulence in the Local Bubble 279
Introduction 280
Radio Astronomy and Diagnostics of Interstellar Plasmas 280
Why the Hot Phase of the Interstellar Medium is of Interest 282
Probing the Local Bubble: The Case of Pulsar B0950+08 283
Relevant Recent Progress in Pulsar Astronomy 284
A New Set of Pulsars to Probe the Local Bubble 284
Results on Plasma and Plasma Turbulence in the Local Bubble 285
Estimates of Other Media Along Pulsar Lines of Sight 287
New Diagnostic Measurements for Local Interstellar Plasmas 289
Summary and Conclusions 291
Acknowledgements 291
References 291
Exotic Clouds in the Local Interstellar Medium 293
Introduction 293
Tiny Scale Atomic Structure (TSAS) 294
Tiny Scale Ionized Structure (TSIS) 295
Low Column Density Clouds 296
Cold Clouds Inside the Local Bubble 297
Comparison with the Cluster of Local Interstellar Clouds 299
Formation and Survival of Cold Clouds 300
Conclusions 301
Acknowledgements 302
References 302
The Local Bubble Debate 304
Introduction 304
Solar Wind Charge Exchange (SWCX) 305
After We Consider the Effects of SWCX, Is There Reason to Believe that the LB Actually Exists?-the Local Bubble vs. Solar Wind Charge Exchange Debate 305
What Measurements Are Needed to Determine How Much Hot Gas May Exist in the Local Bubble? 307
Pressure and Energy Balances in the Local Bubble 308
Pressure Balance 308
Energy Balance 309
Small Scale Structure in the LB 309
Other Important Physical Processes? 309
Acknowledgements 310
References 310
The Origins and Physical Properties of the Complex of Local Interstellar Clouds 311
Introduction 311
The Physical Characteristics of the Complex of Local Interstellar Clouds 312
Primary Observational Evidence 312
Electron Density and Temperature of the LIC 313
Radiative Transfer Models 314
Dust and Elemental Abundances in the LIC 316
LIC Ionization and Thermal Balance 317
The Origin the Complex of Local Interstellar Clouds 320
Summary 321
Acknowledgements 321
References 321
Physical Properties of the Local Interstellar Medium 323
Introduction 323
LISM Observational Database 324
Physical Properties of Individual Structures in the LISM 325
Dynamics 325
Solar Location Relative to LISM Clouds 327
Turbulence and Depletion 327
Inter-cloud Variation of Physical Properties 327
Dynamical Cloud Interactions 328
Cold Clouds 328
Interstellar Radio Scintillation 329
Conclusions and Future Work 329
Acknowledgements 330
References 330
Perspectives on Interstellar Dust Inside and Outside of the Heliosphere 332
Introduction 332
Dust in the Diffuse Interstellar Medium 333
Models for Interstellar Dust: Extinction vs. Elemental Abundances 335
Contribution of Massive Grains to Extinction 338
Could the Dust in the Local ISM Be Atypical? 338
Turbulent Mixing in the ISM 339
Enrichment by Supernova Explosions? 339
Wake of an Evolved Star? 340
Dynamical Concentration of Massive Grains? 340
Structure of the Very Local ISM 342
Summary 342
Acknowledgements 343
References 343
Interstellar Dust Inside and Outside the Heliosphere 345
Introduction 346
Interstellar Dust Inside the Heliosphere 347
Interstellar Dust in the Local Interstellar Cloud 350
Outlook 352
Acknowledgements 352
References 352
Obtaining Spectra of Turbulent Velocity from Observations 355
Introduction 355
Ways to Analyze Position-Position-Velocity Data Cubes 358
Basics of the Formalism 360
Illustration of VCS and VCA Techniques for Power-Law Velocities and Densities 364
Velocity Channel Analysis 364
Velocity Coordinate Spectrum 364
Effects of Self-Absorption 366
Studies of Turbulence with Absorption Lines 366
Comparison of VCA and VCS 368
Numerical Testing 370
Extending VCA and VCS 371
Studying Non-power-Law Turbulence 371
Studies of Nearby Gas 372
Studies of Emission Lines with Emissivity rho2 372
Observational Studies 372
Applying VCA 372
Applying VCS 374
Expected Developments 376
Alternative Approaches 376
Velocity Centroids 376
Wavelets and Principal Component Analysis 376
Spectral Correlation Function 377
Identifying Objects in PPV Space 378
Synergy and Future Work 378
Synergetic Statistical Studies 378
Prospects of Quantiative Studies of PPV Data 379
Outlook onto Big Picture 380
Acknowledgements 381
References 381
Properties and Selected Implications of Magnetic Turbulence for Interstellar Medium, Local Bubble and Solar Wind 384
Introduction 385
Spectrum of Turbulence and Its Anisotropy 386
Anisotropic MHD Turbulence 386
Imbalanced Turbulence 391
Viscous Turbulence 394
Intermittency: Small Volumes with Extreme Conditions 395
Modification of Turbulence by Cosmic Rays 397
Selected Implications of Magnetic Turbulence 399
Cosmic Ray Scattering by Fast Modes of MHD Turbulence 399
Turbulent Reconnection and Cosmic Ray Acceleration 400
Perpendicular Diffusion and Subdiffusion 403
Studying Magnetic Turbulence in Interplanetary Medium Using Comets 405
Discussion and Summary 406
Acknowledgements 407
References 407
The Heliosphere in Time 411
Introduction 412
Basic Model Results 412
Contemporary ISM (LIC) 413
Hot Local Bubble 414
Dense Neutral ISM 415
High Velocity ISM 416
Supernova Remnant Encounters with the Heliosphere 416
Sensitivity of the Heliosphere to ISM Conditions 417
Paleo-Heliosphere 419
Conclusions 420
Acknowledgements 421
References 421
Some Observations Related to the Origin and Evolution of the Local Bubble/Local ISM 422
Introduction 423
The Local ISM Deuterium Abundance Variability and its Link with the Local Bubble/Gould Belt Structure 423
The Deuterium Abundance within 500 pc 423
End of the Debate about Dust Release of Deuterium? 424
The Gould Belt 425
A Link between the LC, the Gould Belt and the D/H Pattern? 426
Highly Charged Ions 427
Charge eXchange (CX) X-Ray Emission 427
The Heliospheric CX Emission and its Impact on LC and Halo Hot Gas 427
Non-Solar Charge Transfer X-Ray Emission? The North Polar Spur? 428
Data Need for a Better Global Picture of the LISM 430
References 430
Origin of the Local Bubble 432
Introduction 432
Search for Nearby OB Associations 433
Results and Discussion 437
The Search for the ``Smoking Gun'' 437
How Many Supernovae and Were They Enough to Create the LB? 440
Conclusions 442
Acknowledgements 443
References 443
Kinetic-Fluid Perspective on Modeling the Heliospheric/Interstellar Medium Interface 444
Introduction 444
Development of the Kinetic-Fluid Model 448
Extent of the Heliosphere in the Tail Region 448
Effect of the 11-Year Solar Activity Cycle 449
Effect of Cosmic Rays 450
Effect of Nonequilibrium of the Pickup and Solar Wind Protons 451
Interstellar Magnetic Field Effect 451
Some Critical Remarks 453
To the Problem of the Heliopause Properties 454
To the Problem of the Heliopause Instability 455
What Is the Role of the Magnetic Field? 456
Whether the MHD Outer Heliosheath Is Bounded 457
Acknowledgements 458
References 458
From the Heliosphere to the Local Bubble-What Have We Learned? 460
Purpose and Philosophy of Summary 460
Outer Heliosphere and Its Boundary Regions 461
Inferring the CHISM from within 462
Structure and Pressure Balance in the Local Bubble 464
Small Scale Structure and Turbulence 466
Future Perspectives 466
Acknowledgements 467
References 467