Abstract: The class of active galactic nuclei termed 'blazars' displays dynamic plasma jets aligned close to the line of sight of the observer. The launching, collimation, acceleration to relativistic flow speeds, and sustainment of these powerful jets is a primary current question in astrophysics. Multiwavelength observations, which probe within a few parsecs of the supermassive black hole, can reveal the mechanisms behind this emission. Blazar jets are well-observed at radio wavelengths; the angular resolution at 43 GHz with the Very Long Baseline Array corresponds to less than a parsec for many objects. We can examine flux density and polarization data to gain insight into the magnetic field alignment, jet shape, knot speeds, and other physical properties. However, at optical wavelengths, blazars are only resolved on a length scale of kiloparsecs. Thus, the location of higher-frequency emission on parsec scales needs to be inferred rather than directly observed. A new technique allows a connection to be made between high-frequency emission and the parsec-scale jet by comparison of polarization characteristics. If the optical electric vector position angle (EVPA) value is close to that of a feature in the radio jet, we can conclude that the emission at both wavelengths is produced by the same mechanism in the same general location. Our work expands this technique by using measurements of time variability during two intensive 10-day multiwavelength campaigns. The study of this data set determines the correlation in variability between the optical EVPA and that at 43 GHz in the parsec-scale jet. This dissertation establishes cospatiality of optical emission with the stationary core seen in 43 GHz images for the majority of our sample of 20 blazars by finding that the EVPAs of the two wavebands agree in value as well as in the timing and manner of their variation. The work then focuses on the magnetic field structure in and around the blazar core. A model is constructed for the production of polarization in each object, and these models are compared to determine the physical nature and structure of the core for blazars as a whole.

Blazars (also known as BL Lac objects), first discovered in 1978, are unusually energetic objects in the extragalactic universe. About 200 are known or suspected. They are radio sources with highly variable optical and radio emission, as well as high polarisation, and their optical spectra normally have no distinguishable features. It is generally accepted that they belong to that class of galaxies with active galactic nuclei, which are presumed to be driven by infall of matter to a supermassive black hole. In this book researchers give a complete summary of the observations of blazars and the theoretical interpretation. A comprehensive listing of confirmed and candidate objects is included. Mechanisms in which the variability can arise from shocks and relativistic jets are discussed. There are at least four different answers given to the question: what is a blazar? This book is a complete overview of the violent activity observed in these extreme active galactic nuclei.

Annotation Papers from a June 2000 meeting discuss multiwavelength monitoring methods for studying active galactic nuclei, the potential of dedicated facilities for multiwavelength monitoring, and future multiwavelength programs. Some topics discussed are multiwavelength observations of blazars, time delays of blazar flares observed at different wavebands, low radiative-efficiency accretion flows, spectrochronography, and variability of the intrinsic UV absorption lines in Seyfert galaxies. Other topics are the variable diffuse continuum emission of broad-line clouds, the MIDEX concept, and the mission. Peterson teaches astronomy at The Ohio State University. This volume lacks a subject index. Annotation c. Book News, Inc., Portland, OR (booknews.com)

(Note: the title actually, but erroneously, shown on the dust jacket, cover, and title page is Multi-Wavelength Continuum Emission of AGN, which is really only the heading of the first section of the volume. Because the correct, but omitted, title subsumes the erroneous title, Book News uses it in order to most accurately establish the reach of the volume.) The proceedings, then, of IAU Symposium No. 159, held in Geneva, Switzerland, August-September 1993, contain almost all of the presentations given at the conference both as posters and as oral invited and contributed papers. They address topics in multi- wavelength continuum emission of AGN; new observations of AGN with specific instruments; variability; correlations between emission components; AGN physics and models; unified schemes and relations with other types of objects; continuum studies; emission processes; x-rays and higher energies; variability; radio emission (maps); line studies; disk structure and emission; and statistical studies and evolution. Annotation copyright by Book News, Inc., Portland, OR

During the past few decades, plasma science has witnessed a great growth in laboratory studies, in simulations, and in space. Plasma is the most common phase of ordinary matter in the universe. It is a state in which ionized matter (even as low as 1%) becomes highly electrically conductive. As such, long-range electric and magnetic fields dominate its behavior. Cosmic plasmas are mostly associated with stars, supernovae, pulsars and neutron stars, quasars and active galaxies at the vicinities of black holes (i.e., their jets and accretion disks). Cosmic plasma phenomena can be studied with different methods, such as laboratory experiments, astrophysical observations, and theoretical/computational approaches (i.e., MHD, particle-in-cell simulations, etc.). They exhibit a multitude of complex magnetohydrodynamic behaviors, acceleration, radiation, turbulence, and various instability phenomena. This Special Issue addresses the growing need of the plasma science principles in astrophysics and presents our current understanding of the physics of astrophysical plasmas, their electromagnetic behaviors and properties (e.g., shocks, waves, turbulence, instabilities, collimation, acceleration and radiation), both microscopically and macroscopically. This Special Issue provides a series of state-of-the-art reviews from international experts in the field of cosmic plasmas and electromagnetic phenomena using theoretical approaches, astrophysical observations, laboratory experiments, and state-of-the-art simulation studies.

The exploration of the subnuclear world is done through increasingly complex experiments covering a wide range of energy and performed in a large variety of environments ranging from particle accelerators, underground detectors to satellites and the space laboratory. Among recent advances one has to indicate, for instance, first results obtained from space and LHC experiments and progress done in preparation of the latter experiments upgrades, including plans for the LHC machine upgrade. The achievement of these research programs calls for novel techniques, new materials and instrumentation to be used in detectors, often of large scale. Therefore, fundamental physics is at the forefront of technological advance and also leads to many applications. Among these, medical applications have a particular importance due to health and social benefits they bring to the public. Sample Chapter(s). Science highlights from the Fenni Observatory (5,046 KB). Contents: Space Experiments and Cosmic Rays Observations; Production and Propagation of Cosmic Rays in the Galaxy and Heliosphere; Dark Matter Searches, Underwater and Underground Experiments; High Energy Physics Experiments; Tracker and Position Sensitive Detectors; Calorimetry; Advanced Detectors, Particles Identication, Devices and Materials in Radiation; Broader Impact Activities, Treatments and Software Application. Readership: Post-graduate students, researchers and engineers.

This review volume is motivated by the recent discovery of high-energy astrophysical neutrinos by IceCube. The aim of the book is to bring together chapters on the status of current and future neutrino observatories with chapters on the implications and possible interpretations of the present observations and their upper limits. Each chapter is a mini-review of one aspect of the subject by leading experts. Taken together, the chapters constitute an up-to-date review of high-energy astrophysical neutrinos and their potential sources.