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Books > Science & Mathematics > Physics > Applied physics & special topics > Astrophysics
The thesis represents the development of an entirely new experimental platform for generating and studying converging radiative shock waves. It was discovered that the application of large magnetic pressures to gas-filled cylindrical metallic tubes could sequentially produce three shocks within the gas. A comprehensive set of instrumentation was devised to explore this system in detail and an exceptionally thorough experimental and theoretical study was carried out in order to understand the source of the shock waves and their dynamics. The research is directed towards some of the most interesting topics in high energy density physics (HEDP) today, namely the interaction of HED material with radiation and magnetic fields, with broad applications to inertial confinement fusion (ICF) and laboratory plasma astrophysics. The work has already generated significant international interest in these two distinct research areas and the results could have significant importance for magnetic ICF concepts being explored at Sandia National Laboratories in the US and for our understanding of the very strong shock waves that are ubiquitous in astrophysics.
The work developed in this thesis addresses very important and relevant issues of accretion processes around black holes. Beginning by studying the time variation of the evolution of inviscid accretion discs around black holes and their properties, the author investigates the change of the pattern of the flows when the strength of the shear viscosity is varied and cooling is introduced. He succeeds to verify theoretical predictions of the so called Two Component Advective Flow (TCAF) solution of the accretion problem onto black holes through numerical simulations under different input parameters. TCAF solutions are found to be stable. And thus explanations of spectral and timing properties (including Quasi-Period Oscillations, QPOs) of galactic and extra-galactic black holes based on shocked TCAF models appear to have a firm foundation.
Simon Murphy's thesis has significant impact on the wide use of the revolutionary Kepler Mission data, leading to a new understanding in stellar astrophysics. It first provides a deep characterisation and comparison of the Kepler long cadence and short cadence data, with particular insight into the Kepler reduction pipeline. It then brings together modern reviews of rotation and peculiarities in A-type stars, and their relationship with the pulsating delta Scuti stars. This is the first combined review of these subjects since the classic monograph by Sydney Wolff, "The A stars," was published three decades ago. The thesis presents a novel technique, Super-Nyquist Asteroseismology, that has opened up the asteroseismic study of thousands of Kepler stars. It shows case studies of delta Scuti stars examining amplitude growth, super-Nyquist pulsation, and pulsation in a high-amplitude, population II SX Phoenicis star in a 343-d binary. This work informs our understanding of the relation of rotation to peculiarity, hence has applications to atomic diffusion theory. This is a brilliant thesis written in an elegant and engaging style.
This book is dedicated to readers who want to learn fluid dynamics from the beginning. It assumes a basic level of mathematics knowledge that would correspond to that of most second-year undergraduate physics students and examines fluid dynamics from a physicist's perspective. As such, the examples used primarily come from our environment on Earth and, where possible, from astrophysics. The text is arranged in a progressive and educational format, aimed at leading readers from the simplest basics to more complex matters like turbulence and magnetohydrodynamics. Exercises at the end of each chapter help readers to test their understanding of the subject (solutions are provided at the end of the book), and a special chapter is devoted to introducing selected aspects of mathematics that beginners may not be familiar with, so as to make the book self-contained.
This book contains the elaborated and updated versions of the 24 lectures given at the 43rd Saas-Fee Advanced Course. Written by four eminent scientists in the field, the book reviews the physical processes related to star formation, starting from cosmological down to galactic scales. It presents a detailed description of the interstellar medium and its link with the star formation. And it describes the main numerical computational techniques designed to solve the equations governing self-gravitating fluids used for modelling of galactic and extra-galactic systems. This book provides a unique framework which is needed to develop and improve the simulation techniques designed for understanding the formation and evolution of galaxies. Presented in an accessible manner it contains the present day state of knowledge of the field. It serves as an entry point and key reference to students and researchers in astronomy, cosmology, and physics.
This brief book provides an overview of the gravitational orbital evolution of few-body systems, in particular those consisting of three bodies. The authors present the historical context that begins with the origin of the problem as defined by Newton, which was followed up by Euler, Lagrange, Laplace, and many others. Additionally, they consider the modern works from the 20th and 21st centuries that describe the development of powerful analytical methods by Poincare and others. The development of numerical tools, including modern symplectic methods, are presented as they pertain to the identification of short-term chaos and long term integrations of the orbits of many astronomical architectures such as stellar triples, planets in binaries, and single stars that host multiple exoplanets. The book includes some of the latest discoveries from the Kepler and now K2 missions, as well as applications to exoplanets discovered via the radial velocity method. Specifically, the authors give a unique perspective in relation to the discovery of planets in binary star systems and the current search for extrasolar moons.
Subtlety in Relativity is the only book that has been written after the author's discovery of a new way in which wave phenomena occur-the emission origin of waves. This drastically changes most issues of the old debate over the world being either deterministic or probabilistic. The emission origin of waves is not incompatible with the ideas of quantum theory; rather, this new and novel way in which waves can be generated justifies the use of mathematical and probabilistic methods of quantum theory. However, the emission origin of waves shows that quantum theory is statistically incomplete in, precisely, Einstein's sense. There exists, then, a certain, previously unexplored, conceptual framework underlying the ideas of quantum theory. Whether this is the theory that Einstein and others were looking for then, how this way of thinking is related to the ideas of relativity, and whether this is a relativistic theory in the usual sense of this word are questions this book answers. The book demonstrates how the Doppler effect with acceleration is essential to interpreting astronomical observations. It also offers a detailed and self-sufficient technical background of mathematical ideas of category theory. The book is divided into two parts. The first is less mathematical and more conceptual in its orientation. The second focuses on mathematical ideas needed to implement physical concepts. The book is a great reference for advanced undergraduate- and graduate-level students of physics and researchers in physics, astronomy, and cosmology, who will gain a deeper understanding of relativity from it.
The search for gravitational radiation with optical interferometers is gaining momentum worldwide. Beside the VIRGO and GEO gravitational wave observatories in Europe and the two LIGOs in the United States, which have operated successfully during the past decade, further observatories are being completed (KAGRA in Japan) or planned (ILIGO in India). The sensitivity of the current observatories, although spectacular, has not allowed direct discovery of gravitational waves. The advanced detectors (Advanced LIGO and Advanced Virgo) at present in the development phase will improve sensitivity by a factor of 10, probing the universe up to 200 Mpc for signal from inspiraling binary compact stars. This book covers all experimental aspects of the search for gravitational radiation with optical interferometers. Every facet of the technological development underlying the evolution of advanced interferometers is thoroughly described, from configuration to optics and coatings and from thermal compensation to suspensions and controls. All key ingredients of an advanced detector are covered, including the solutions implemented in first-generation detectors, their limitations, and how to overcome them. Each issue is addressed with special reference to the solution adopted for Advanced VIRGO but constant attention is also paid to other strategies, in particular those chosen for Advanced LIGO.
This thesis presents theoretical and numerical studies on phenomenological description of the quark–gluon plasma (QGP), a many-body system of elementary particles. The author formulates a causal theory of hydrodynamics for systems with net charges from the law of increasing entropy and a momentum expansion method. The derived equation results can be applied not only to collider physics, but also to the early universe and ultra-cold atoms. The author also develops novel off-equilibrium hydrodynamic models for the longitudinal expansion of the QGP on the basis of these equations. Numerical estimations show that convection and entropy production during the hydrodynamic evolution are key to explaining excessive charged particle production, recently observed at the Large Hadron Collider. Furthermore, the analyses at finite baryon density indicate that the energy available for QGP production is larger than the amount conventionally assumed.
Several of the very foundations of the cosmological standard model — the baryon asymmetry of the universe, dark matter, and the origin of the hot big bang itself — still call for an explanation from the perspective of fundamental physics. This work advocates one intriguing possibility for a consistent cosmology that fills in the theoretical gaps while being fully in accordance with the observational data. At very high energies, the universe might have been in a false vacuum state that preserved B-L, the difference between the baryon number B and the lepton number L as a local symmetry. In this state, the universe experienced a stage of hybrid inflation that only ended when the false vacuum became unstable and decayed, in the course of a waterfall transition, into a phase with spontaneously broken B-L symmetry. This B-L Phase Transition was accompanied by tachyonic preheating that transferred almost the entire energy of the false vacuum into a gas of B-L Higgs bosons, which in turn decayed into heavy Majorana neutrinos. Eventually, these neutrinos decayed into massless radiation, thereby producing the entropy of the hot big bang, generating the baryon asymmetry of the universe via the leptogenesis mechanism and setting the stage for the production of dark matter. Next to a variety of conceptual novelties and phenomenological predictions, the main achievement of the thesis is hence the fascinating notion that the leading role in the first act of our universe might have actually been played by neutrinos.
Pulsar timing is a promising method for detecting gravitational waves in the nano-Hertz band. In his prize winning Ph.D. thesis Rutger van Haasteren deals with how one takes thousands of seemingly random timing residuals which are measured by pulsar observers, and extracts information about the presence and character of the gravitational waves in the nano-Hertz band that are washing over our Galaxy. The author presents a sophisticated mathematical algorithm that deals with this issue. His algorithm is probably the most well-developed of those that are currently in use in the Pulsar Timing Array community. In chapter 3, the gravitational-wave memory effect is described. This is one of the first descriptions of this interesting effect in relation with pulsar timing, which may become observable in future Pulsar Timing Array projects. The last part of the work is dedicated to an effort to combine the European pulsar timing data sets in order to search for gravitational waves. This study has placed the most stringent limit to date on the intensity of gravitational waves that are produced by pairs of supermassive black holes dancing around each other in distant galaxies, as well as those that may be produced by vibrating cosmic strings. Rutger van Haasteren has won the 2011 GWIC Thesis Prize of the Gravitational Wave International Community for his innovative work in various directions of the search for gravitational waves by pulsar timing. The work is presented in this Ph.D. thesis.
In this PhD thesis, which was nominated for publication in this series by the Astronomical Institute at Charles University, Prague, the author investigates the orbital evolution of an initially thin stellar disc around a supermassive black hole, considering various perturbative sources of gravity. His findings, obtained by both direct numerical N-body modelling and using standard perturbation methods, offer a viable theoretical explanation for the observed configuration of young stars in the Galactic Centre. This marks a significant contribution to a topic of great interest in contemporary astrophysics. The author also shows in his thesis that a secular instability (m = 1 mode) may occur in the embedding spherical cluster of old stars. This increases the richness of possible evolution scenarios of the embedding cluster and may lead to effective feeding of supermassive black holes through tidal disruption of stars on extremely eccentric orbits.
Neutrinos continue to be the most mysterious and, arguably, the most fascinating particles of the Standard Model as their intrinsic properties such as absolute mass scale and CP properties are unknown. The open question of the absolute neutrino mass scale will be addressed with unprecedented accuracy by the Karlsruhe Tritium Neutrino (KATRIN) experiment, currently under construction. This thesis focusses on the spectrometer part of KATRIN and background processes therein. Various background sources such as small Penning traps, as well as nuclear decays from single radon atoms are fully characterized here for the first time. Most importantly, however, it was possible to reduce the background in the spectrometer by more than five orders of magnitude by eliminating Penning traps and by developing a completely new background reduction method by stochastically heating trapped electrons using electron cyclotron resonance (ECR). The work beautifully demonstrates that the obstacles and challenges in measuring the absolute mass scale of neutrinos can be met successfully if novel experimental tools (ECR) and novel computing methods (KASSIOPEIA) are combined to allow almost background-free tritium ss-spectroscopy.
The second edition of Solar System Astrophysics: Planetary Atmospheres and the Outer Solar System provides a timely update of our knowledge of planetary atmospheres and of the bodies of the outer solar system and their analogs in other planetary systems. This volume begins with an expanded treatment of the physics, chemistry, and meteorology of the atmospheres of the Earth, Venus, and Mars, moving on to their magnetospheres and then to a full discussion of the gas and ice giants and their properties. From here, attention switches to the small bodies of the solar system, beginning with the natural satellites. The comets, meteors, meteorites, and asteroids are discussed in order, and the volume concludes with the origin and evolution of our solar system. Finally, a fully revised section on extrasolar planetary systems puts the development of our system in a wider and increasingly well understood galactic context. All of the material is presented within a framework of historical importance. This book and its sister volume, Solar System Astrophysics: Background Science and the Inner Solar system, are pedagogically well written, providing clearly illustrated explanations, for example, of such topics as the numerical integration of the Adams-Williamson equation, the equations of state in planetary interiors and atmospheres, Maxwell's equations as applied to planetary ionospheres and magnetospheres, and the physics and chemistry of the Habitable Zone in planetary systems. Together, the volumes form a comprehensive text for any university course that aims to deal with all aspects of solar and extra-solar planetary systems. They will appeal separately to the intellectually curious who would like to know how just how far our knowledge of the solar system has progressed in recent years.
Proceedings from the 2012 Fourth International Meeting on Gravitation and Cosmology, focusing on accelerated cosmic expansion This volume provides both an update and a review of the state of alternative theories of gravity in connection with the accelerated expansion of the universe issue. Different theoretical proposals exist to explain the acceleration in the cosmic expansion, generating the dark energy issue and opening the possibility to theories of gravity alternative to general relativity. Related issues such as the dark matter problem are also surveyed in order to give the readers profound insight on the subject from different points of view. Comprised of short talks and plenary lectures given by leading experts in the field, some of them with brilliant and historic contributions, the book allows the reader to find readable and referenced surveys in topics like f(R) theories, the dark matter and dark energy issues, Modified Newtonian Dynamics (MOND) scenarios, f(T) theories, scalar-tensor theories derived from non-Riemannian geometries, emergent universes, the cosmological constant and other topics of current interest for younger and senior physicists and graduate students. These proceedings are from the Fourth International Meeting on Gravitation and Cosmology, held in Guadalajara, Jalisco, México, from 20 - 25 May, 2012, was sponsored by ICTP- Trieste, Italy and COECyTJAL-Universidad de Guadalajara, México. This event is a series of scientific meetings started in 2004 in Cuba, focusing on current and selected topics in the fields of gravitation and cosmology.
This thesis is devoted to ANTARES, the first underwater neutrino telescope in the Mediterranean sea. As the main scientific analysis, a search for high-energy neutrino emission from the region of the Fermi bubbles has been performed using data from the ANTARES detector. A method for the background estimation using off-zones has been developed specially for this measurement. A new likelihood for the limits calculation which treats both observations in the on-zone and in the off-zone in the similar way and also includes different systematic uncertainties has been constructed. The analysis of 2008–2011 ANTARES data yielded a 1.2 σ excess of events in the Fermi bubble regions, compatible with the no-signal hypothesis. For the optimistic case of no energy cutoff in the flux, the upper limit is within a factor of three of the prediction of the purely hadronic model based on the measured gamma-ray flux. The sensitivity improves as more data are accumulated (more than 65% gain in the sensitivity is expected once 2012–2016 data are added to the analysis).
The First Edition of The Sun from Space, completed in 1999, focused on the early accomplishments of three solar spacecraft, SOHO, Ulysses, and Yohkoh, primarily during a minimum in the Sun's 11-year cycle of magnetic activity. The comp- hensive Second Edition includes the main ndings of these three spacecraft over an entire activity cycle, including two minima and a maximum, and discusses the signi cant results of six more solar missions. Four of these, the Hinode, RHESSI, STEREO, and TRACE missions were launched after the First Edition was either nished or nearly so, and the other two, the ACE and Wind spacecraft, extend our investigations from the Sun to its varying input to the Earth. The Second Edition does not contain simple updates or cosmetic patch ups to the material in the First Edition. It instead contains the relevant discoveries of the past decade, integrated into chapters completely rewritten for the purpose. This provides a fresh perspective to the major topics of solar enquiry, written in an enjoyable, easily understood text accessible to all readers, from the interested layperson to the student or professional.
Short Historical Overview In the 1940s, two phenomena in the ?eld of cosmic rays (CR) forced scientists to think that the Sun is a powerful source of high-energy particles. One of these was discovered because of the daily solar variation of CR, which the maximum number of CR observed near noon (referring to the existence of continuous ?ux of CR from the direction of the Sun); this became the experimental basis of the theory that CR's originate from the Sun (or, for that matter, from within the solar system) (Alfven 1954). The second phenomenon was discovered when large ?uxes of high energy particles were detected from several solar ?ares, or solar CR. These are the - called ground level events (GLE), and were ?rst observed by ionization chambers shielded by 10 cm Pb (and detected mainly from the secondary muon-component CR that they caused) during the events of the 28th of February 1942, the 7th of March 1942, the 25th of July 1946, and the 19th of November 1949. The biggest such event was detected on the 23rd of February 1956 (see the detailed description in Chapters X and XI of Dorman, M1957). The ?rst phenomenon was investigated in detail in Dorman (M1957), by ?rst correcting experimental data on muon temperature effects and then by using coupling functions to determine the change in particle energy caused by the solar-diurnal CR variation.
Where do most stars (and the planetary systems that surround them) in the Milky Way form? What determines whether a young star cluster remains bound (such as an open or globular cluster), or disperses to join the field stars in the disc of the Galaxy? These questions not only impact understanding of the origins of stars and planetary systems like our own (and the potential for life to emerge that they represent), but also galaxy formation and evolution, and ultimately the story of star formation over cosmic time in the Universe. This volume will help readers understand our current views concerning the answers to these questions as well as frame new questions that will be answered by the European Space Agency's Gaia satellite that was launched in late 2013. The book contains the elaborated notes of lectures given at the 42nd Saas-Fee Advanced Course "Dynamics of Young Star Clusters & Associations" by Cathie Clarke (University of Cambridge) who presents the theory of star formation and dynamical evolution of stellar systems, Robert Mathieu (University of Wisconsin) who discusses the kinematics of star clusters and associations, and I. Neill Reid (S pace Telescope Science Institute) who provides an overview of the stellar populations in the Milky Way and speculates on from whence came the Sun. As part of the Saas-Fee Advanced Course Series, the book offers an in-depth introduction to the field serving as a starting point for Ph.D. research and as a reference work for professional astrophysicists.
,This is the updated, widely revised, restructured and expanded third edition of Lena et al.'s successful work Observational Astrophysics. It presents a synthesis on tools and methods of observational astrophysics of the early 21st century. Written specifically for astrophysicists and graduate students, this textbook focuses on fundamental and sometimes practical limitations on the ultimate performance that an astronomical system may reach, rather than presenting particular systems in detail. In little more than a decade there has been extraordinary progress in imaging and detection technologies, in the fields of adaptive optics, optical interferometry, in the sub-millimetre waveband, observation of neutrinos, discovery of exoplanets, to name but a few examples. The work deals with ground-based and space-based astronomy and their respective fields. And it also presents the ambitious concepts behind space missions aimed for the next decades. Avoiding particulars, it covers the whole of the electromagnetic spectrum, and provides an introduction to the new forms of astronomy becoming possible with gravitational waves and neutrinos. It also treats numerical aspects of observational astrophysics: signal processing, astronomical databases and virtual observatories.
In The Earth as a Distant Planet, the authors become external observers of our solar system from a distance and try to determine how one can understand how Earth, the third in distance to the central star, is essentially unique and capable of sustaining life. The knowledge gained from this original perspective is then applied to the search for other planets outside the solar system, or exoplanets. Since the discovery in 1992 of the first exoplanet, the number of planet detections has increased exponentially and ambitious missions are already being planned for the future. The exploration of Earth and the rest of the rocky planets are Rosetta stones in classifying and understanding the multiplicity of planetary systems that exist in our galaxy. In time, statistics on the formation and evolution of exoplanets will be available and will provide vital information for solving some of the unanswered questions about the formation, as well as evolution of our own world and solar system. Special attention is paid to the biosignatures (signs of life) detectable in the Earth's reflected spectra and the search for life in the universe. The authors are experts on the subject of extrasolar planets. They provide an introductory but also very much up-to-date text, making this book suitable for researchers and for advanced students in astronomy and astrophysics.
These pages present a collection of recent papers primarily documenting the nascent science of neutrino geophysics. Most of the papers followed from talks given at Neutrino Sciences 2005: Neutrino Geophysics held at the University of Hawaii in December 2005. Several papers were solicited later in an effort to make the collection as comprehensive as possible. Every paper was scrutinized by an external reviewer to assure the quality of scientific content.
This book reviews the phenomenology displayed by relativistic jets as well as the most recent theoretical efforts to understand the physical mechanisms at their origin. Relativistic jets have been observed and studied in Active Galactic Nuclei (AGN) for about half a century and are believed to be fueled by accretion onto a supermassive black hole at the center of the host galaxy. Since the first discovery of relativistic jets associated with so-called "micro-quasars" much more recently, it has seemed clear that much of the physics governing the relativistic outflows in stellar X-ray binaries harboring black holes and in AGN must be common, but acting on very different spatial and temporal scales. With new observational and theoretical results piling up every day, this book attempts to synthesize a consistent, unified physical picture of the formation and disruption of jets in accreting black-hole systems. The chapters in this book offer overviews accessible not only to specialists but also to graduate students and astrophysicists working in other areas. Covered topics comprise Relativistic jets in stellar systems Launching of AGN jets Parsec-scale AGN jets Kiloparsec-scale AGN jets Black hole magnetospheres Theory of relativistic jets The structure and dynamics of the inner accretion disk The origin of the jet magnetic field X-ray observations, phenomenology, and connection with theory
This thesis discusses the evolution of galaxies through the study of the morphology, kinematics, and star formation properties of a sample of nearby galaxies. The main body of the thesis describes the kinematic observations with the GHaFAS Fabry-Perot instrument on the William Herschel Telescope of a sample of 29 spiral galaxies. The work is closely related to the Spitzer Survey of Stellar Structure in Galaxies, and uses the mid-infrared data of that survey to determine key parameters of the galaxies studied. From these data, important results are obtained on streaming and other non-circular motions in galaxies, on the distribution and rates of star formation, and on how correlations of these parameters and of the rotation curve shape with basic galaxy parameters yield clues on the evolutionary processes taking place in disk galaxies.
This course-tested textbook conveys the fundamentals of magnetic fields and relativistic plasma in diffuse cosmic media, with a primary focus on phenomena that have been observed at different wavelengths. Theoretical concepts are addressed wherever necessary, with derivations presented in sufficient detail to be generally accessible. In the first few chapters the authors present an introduction to various astrophysical phenomena related to cosmic magnetism, with scales ranging from molecular clouds in star-forming regions and supernova remnants in the Milky Way, to clusters of galaxies. Later chapters address the role of magnetic fields in the evolution of the interstellar medium, galaxies and galaxy clusters. The book is intended for advanced undergraduate and postgraduate students in astronomy and physics and will serve as an entry point for those starting their first research projects in the field. |
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