Plasma Radiation Mechanisms In Astrophysics

The paper discusses problems and applications of plasma physics and its revelance to astrophysics. A method of interpreting radio emission of variable quasars is suggested.

The paper discusses problems and applications of plasma physics and its revelance to astrophysics. A method of interpreting radio emission of variable quasars is suggested.

Interest in the problem of interaction between radiation and astrophysical plasmas arose decades ago. Initially, this was closely related to the discovery of radio emission from the Sun and Galaxy which alerted theoretical radio astronomers to the problem of the origin of extra-terrestrial radio emission. It has been found that the observed radio emission from cosmic sources is generated by virtue of the mechanisms which work mainly in plasma (an ionized gas). Recently, the theory of generation and propagation of radiation in astrophysical plasmas has outgrown its parent domain of theoretical radio astronomy and is being successfully applied to other fields, such as high-energy astrophysics. General results obtained in this field may also help to better understand the complicated phenomena in laboratory plasmas on the Earth. At the same time, analysis of interaction between radiation and astrophysical plasmas under extreme conditions (strong magnetic fields of white dwarfs and neutron stars or strong gravitational fields in the vicinity of black holes) stimulates the development of plasma physics as a whole. In fact, the physics of plasma under extreme conditions in space is a new branch of fundamental science. The monograph contains the description of physical processes involved in interaction between radiation and astrophysical plasmas. It comprises the reasonable minimum necessary for understanding the emission and propagation of electromagnetic waves in astrophysical plasmas; without this minimum one could not succeed in interpreting the results of a number of astronomical observations. Audience: This monograph will be useful for graduate and post-graduate students and young scientists as a textbook on plasma astrophysics and the issues of plasma physics dealing with radiation. At the same time, the book can be used by specialists on astrophysics, radio astronomy and plasma physics.

Plasma Astrophysics is a translation from the Russian language; the topics discussed are based on lectures given by V.N. Tsytovich at several universities. The book describes the physics of the various phenomena and their mathematical formulation connected with plasma astrophysics. This book also explains the theory of the interaction of fast particles plasma, their radiation activities, as well as the plasma behavior when exposed to a very strong magnetic field. The text describes the nature of collective plasma processes and of plasma turbulence. One author explains the method of elementary excitation which he has developed. The book also discusses the sporadic radio-emission of the sun, galactic nuclei, radio-galaxies, quasars, and pulsars. The book explains that problems involving terrestrial plasma can be split into parts; in astrophysics, the approach is different. For example, particle acceleration is determined by turbulence spectra that in turn depends on the energy distribution of the accelerated particles. The authors also give theoretical results based on many calculations analysis of observational data: Tsytovich contributes new theoretical calculations. This book can prove helpful for nuclear scientists and researchers working with plasma physics or astro-physics.

Radiative Processes in Astrophysics: This clear, straightforward, and fundamental introduction is designed to present-from a physicist's point of view-radiation processes and their applications to astrophysical phenomena and space science. It covers such topics as radiative transfer theory, relativistic covariance and kinematics, bremsstrahlung radiation, synchrotron radiation, Compton scattering, some plasma effects, and radiative transitions in atoms. Discussion begins with first principles, physically motivating and deriving all results rather than merely presenting finished formulae. However, a reasonably good physics background (introductory quantum mechanics, intermediate electromagnetic theory, special relativity, and some statistical mechanics) is required. Much of this prerequisite material is provided by brief reviews, making the book a self-contained reference for workers in the field as well as the ideal text for senior or first-year graduate students of astronomy, astrophysics, and related physics courses. Radiative Processes in Astrophysics also contains about 75 problems, with solutions, illustrating applications of the material and methods for calculating results. This important and integral section emphasizes physical intuition by presenting important results that are used throughout the main text; it is here that most of the practical astrophysical applications become apparent.

In May 1998 a hundred renowned scientists from 20 different countries met at the Max-Planck-Institut für Aeronomie to communicate their latest results and ideas in astrophysical and space plasma, as a follow-up to previous similar meetings which were held in Varenna, Abastumai, Potsdam, Toki and Guaruja. The main papers emerging from this meeting are collected in this volume. They deal with fundamental plasma phenomena, particle and radiation processes in astrophysics and space physics as the origin of magnetic activity, the basic mechanisms of particle acceleration and plasma heating common to plasma in galaxies and at the sun as well as in planetary magnetospheres. New observational results from YOHKOH, SOHO and other missions are presented. Using these, the basic physical processes leading to coronal heating and solar/stellar wind acceleration are discussed. Other topics are the microphysics of shock waves and transport phenomena in collisionless plasmas and the physics of thin plasma boundaries. The volume also treats the ionic composition of plasma and dust in the Universe and their observability in the solar system. A CD-ROM is attached which adds a valuable multimedia component, illuminating results of observations, theory and simulations. Everyone interested in astrophysical plasmas, its radiation and charged particle aspects, and advanced or even beginning students will find references to nearly all modern aspects of plasma astrophysics and space physics as well as an overview of current research results.

Magnetic energy release plays an important role in a wide variety of cosmic objects such as the Sun, stellar coronae, stellar and galactic accretion disks and pulsars. The observed radio, X-ray and gamma-ray emission often directly results from magnetic `flares', implying that these processes are spatially fragmented and of an impulsive nature. A true understanding of these processes requires a combined magnetohydrodynamical and plasma physical approach. Fragmented Energy Release in Sun and Stars: the Interface between MHD and Plasma Physics provides a comprehensive, interdisciplinary summary of magnetic energy release in the Sun and stars, in accretion disks, in pulsar magnetospheres and in laboratory plasmas. These proceedings include papers on both theoretical and observational aspects. Fragmented Energy Release in Sun and Stars: the Interface between MHD and Plasma Physics is for researchers in the fields of solar physics, stellar astrophysics and (laboratory) plasma physics and is a useful resource book for graduate level astrophysics courses.

In June of 1996, at the idyllic seaside resort of Guarujá, Brazil, a renowned group of researchers in space and astrophysical plasmas met to provide a forum on Advanced Topics on Astrophysical and Space Plasmas at a school consisting of some 60 students and teachers, mainly from Brazil and Argentina, but also from all the other parts of the globe. The purpose was to provide an update on the latest theories, observations, and simulations of space-astrophysical plasma phenomena. The topics covered included space plasma mechanisms for particle acceleration, nonthermal emission in cosmic plasma, magnetohydrodynamic instabilities in solar, interstellar, and other cosmic objects, magnetic field line reconnection and merging, the nonlinear and often chaotic structure of astrophysical plasmas, and the advances in high performance supercomputing resources to replicate the observed phenomena. The lectures were presented by Professor Mark Birkinshaw of the Harvard-Smithsonian Center for Astrophysics and the University of Bristol; Dr Anthony Peratt, Los Alamos National Laboratory Scientific Advisor to the United States Department of Energy; Dr Dieter Biskamp of the Max Planck Institute for Plasma Physics, Garching, Germany; Professor Donald Melrose, Director, Centre for Theoretical Astrophysics, University of Sydney, Australia; Professor Abraham Chian of the National Institute for Space Research, Brazil; and Professor Nelson Fiedler-Ferrara of the University of São Paulo, Brazil. As summarized by Professor Reuven Opher, Institute of Astronomy and Geophysics, University of São Paulo, the advanced or interested student of space and astrophysical plasmas will find reference to nearly all modern aspects in the field of Plasma Astrophysics and Cosmology in the presented lectures.