MHD Flows in Compact Astrophysical Objects: Accretion, Winds and Jets

ISBN-13: 9783642261770 / Angielski / Miękka / 2012 / 425 str.

Vasily S. Beskin

Opis

Accretion flows, winds and jets of compact astrophysical objects and stars are generally described within the framework of hydrodynamical and magnetohydrodynamical (MHD) flows. Analytical analysis of the problem provides profound physical insights, which are essential for interpreting and understanding the results of numerical simulations. Providing such a physical understanding of MHD Flows in Compact Astrophysical Objects is the main goal of this book, which is an updated translation of a successful Russian graduate textbook. The book provides the first detailed introduction into the method of the Grad-Shafranov equation, describing analytically the very broad class of hydrodynamical and MHD flows. It starts with the classical examples of hydrodynamical accretion onto relativistic and nonrelativistic objects. The force-free limit of the Grad-Shafranov equation allows us to analyze in detail the physics of the magnetospheres of radio pulsars and black holes, including the Blandford-Znajek process of energy extraction from a rotating black hole immersed in an external magnetic field. Finally, on the basis of the full MHD version of the Grad-Shafranov equation the author discusses the problems of jet collimation and particle acceleration in Active Galactic Nuclei, radio pulsars, and Young Stellar Objects. The comparison of the analytical results with numerical simulations demonstrates their good agreement. Assuming that the reader is familiar with the basic physical and mathematical concepts of General Relativity, the author uses the 3+1 split approach which allows the formulation of all results in terms of physically clear language of three dimensional vectors. The book contains detailed derivations of equations, numerous exercises, and an extensive bibliography. It therefore serves as both an introductory text for graduate students and a valuable reference work for researchers in the field.

Recenzje

From the reviews: "The volume primarily addresses the Grad-Shafranov approach to describe axisymmetric stationary flows around astrophysical objects, including ones where General Relativity is important. ... Each chapter has an abstract and an introduction to the kinds of sources to which its equations apply. ... the astrophysics-group ... able to make more use of it than I can." (Viginia Trimble, The Observatory, Vol. 130 (1214), June, 2010)

Spis treści

Preface.............................................................. 5 Introduction......................................................... 9 Chapter 1 Hydrodynamic limit - classical problems of accretion and ejection.... 13 1.1 Astrophysical introduction - accretion onto compact objects.... 13 1 1 1 Accretion disks........................................... 14 1.1.2 Standard model............................................ 17 1.1.3 ADAF, ADIOS, etc.......................................... 20 1.2 Basic properties of transonic hydrodynamical flows............. 22 1.2.1 Basic equations........................................... 22 1.2.2 Spherically symmetric flow................................ 24 1.2.3 Plane potential flow...................................... 27 1.3 Axisymmetric stationary flows - nonrelativistic case........... 34 1.3.1 Basic equations........................................... 34 1.3.2 Mathematical interlude - covariant language............... 35 1.3.3 Structure of the two-dimensional flow..................... 37 1.3.4 Bondi-Hoyle accretion..................................... 45 1.3.5 Ejection from slowly rotating star........................ 49 1.4 Axisymmetric stationary accretion onto black hole.............. 57 1.4.1 Physical interlude - (3+1)-split in the Kerr metric....... 57 1.4.2 Basic equations........................................... 61 1.4.3 Exact solutions........................................... 65 1.4.4 Bondi-Hoyle accretion - relativistic limit................ 67 1.4.5 Accretion onto slowly rotating black hole................. 70 1.4.6 Accretion of a gas with small angular momentum onto nonrotating black hole......... 71 1.4.7 Thin transonic disk....................................... 77 1.5 Conclusion..................................................... 87 1 Chapter 2 Force-free limit - radio pulsar magnetosphere........................ 89 2.1 Astrophysical introduction..................................... 89 2.2 Main physical processes........................................ 92 2.2.1 Vacuum approximation...................................... 92 2.2.2 Particle creation in a strong magnetic field.............. 96 2.2.3 Structure of the magnetosphere............................ 99 2.3 Generation of secondary plasma.................................104 2.3.1 'Internal gap'............................................104 2.3.2 Neutron star surface......................................109 2.3.3 Propagation of gamma-quanta in superstrong magnetic field......................110 2.3.4 Effects of the general relativity.........................111 2.3.5 Particle generation in the magnetosphere................. 113 2.3.6 'Hollow cone' model...................................... 114 2.3.7 Particle generation - 'external gap'..................... 119 2.4 Pulsar equation............................................... 119 2.4.1 Force-free approximation. Magnetization parameter........ 119 2.4.2 Electromagnetic field. Integrals of motion............... 121 2.4.3 Grad-Shafranov equation.................................. 124 2.4.4 Mathematical interlude - quasi stationary approach....... 127 2.5 Energy loss of radio pulsars.................................. 130 2.5.1 Current loss mechanism................................... 130 2.5.2 Braking of inclined and orthogonal rotator............... 133 2.6 Structure of the magnetosphere................................ 141 2.6.1 Exact solutions.......................................... 141 2.6.2 Structure of the magnetosphere with longitudinal currents 158 2.6.3 Models of th