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Author: Pranab Ghosh Publisher: World Scientific ISBN: 9810247443 Category : Science Languages : en Pages : 793
Book Description
This book is an introduction to pulsars, a key area in high energy astrophysics with continuing potential for fundamental discoveries. Throughout the book runs the unifying thread of the evolutionary link between rotation-powered pulsars and accretion-powered pulsars ? a milestone of modern astrophysics. Early textbooks on pulsars dealt almost entirely with rotation-powered ones, while accounts of pulsars in volumes on X-ray binaries focused almost exclusively on accretion-powered ones. This is the first textbook to treat these two kinds of pulsars simultaneously with equal importance, stressing the fact that both are rotating, magnetic neutron stars, operating under different conditions during different parts of their lives. It describes the observational properties of both kinds of pulsars, summarizes our physical understanding of these properties, and pays detailed attention to the physics of superdense matter which neutron stars are composed of, as well as to the superfluidity which is expected to occur in neutron stars. Evolution from rotation-power to accretion-power, and vice versa, are carefully described. The effects of the strong magnetic fields of neutron stars on themselves, their emission properties, and their environments are discussed, as are the origin and evolution of such magnetic fields. Also treated is the superbly accurate verification of Einstein's theory of general relativity through timing studies of binary pulsars, which led to the award of the Nobel Prize to Hulse and Taylor in 1993. On each topic, the book starts with simple, basic physical concepts, and builds up the exposition to the point where the latest and most exciting developments become accessible to the reader.
Author: Pranab Ghosh Publisher: World Scientific ISBN: 9810247443 Category : Science Languages : en Pages : 793
Book Description
This book is an introduction to pulsars, a key area in high energy astrophysics with continuing potential for fundamental discoveries. Throughout the book runs the unifying thread of the evolutionary link between rotation-powered pulsars and accretion-powered pulsars ? a milestone of modern astrophysics. Early textbooks on pulsars dealt almost entirely with rotation-powered ones, while accounts of pulsars in volumes on X-ray binaries focused almost exclusively on accretion-powered ones. This is the first textbook to treat these two kinds of pulsars simultaneously with equal importance, stressing the fact that both are rotating, magnetic neutron stars, operating under different conditions during different parts of their lives. It describes the observational properties of both kinds of pulsars, summarizes our physical understanding of these properties, and pays detailed attention to the physics of superdense matter which neutron stars are composed of, as well as to the superfluidity which is expected to occur in neutron stars. Evolution from rotation-power to accretion-power, and vice versa, are carefully described. The effects of the strong magnetic fields of neutron stars on themselves, their emission properties, and their environments are discussed, as are the origin and evolution of such magnetic fields. Also treated is the superbly accurate verification of Einstein's theory of general relativity through timing studies of binary pulsars, which led to the award of the Nobel Prize to Hulse and Taylor in 1993. On each topic, the book starts with simple, basic physical concepts, and builds up the exposition to the point where the latest and most exciting developments become accessible to the reader.
Author: Prakash Arumugasamy Publisher: ISBN: Category : Languages : en Pages :
Book Description
The dissertation focuses on the study of rotation-powered pulsars, the primary observational manifestation of neutron stars. These objects are powerful sources of electromagnetic radiation and relativistic particles whose emission is provided by the loss of pulsar rotational energy. Understanding the evolution of pulsars, which happens over billion year timescales, requires detection and study of pulsars at different stages of evolution. I present detailed X-ray analyses of pulsars at four distinct stages of evolution and compare their emission behavior with that of other pulsars expected to be in similar evolutionary stages. I also show key characteristics of the pulsars that make them unique in their group. I start with a young and energetic pulsar, PSR J2022+3842 (characteristic age approximately 9 kyr, spin-down power = 3E37 erg/s), with powerful non-thermal emission. X-ray timing of the pulsar revealed double-peaked X-ray profile with a period twice the previously established value. Our analysis allowed us to update the pulsar's spin-down power and X-ray efficiency using the correct timing results, which brought the pulsar more in-line with other young X-ray pulsars. I also provide the phase-dependent behavior of the pulsar's non-thermal emission. Pulsars with true ages, often substituted by characteristic age, below ~ 100 kyr are considered young and ones with ages > 1 Myr are considered old, with the 'middle-aged' pulsars in the middle. My next pulsar is a 1.8 Myr old J1836+5925 (spin-down power = 1E34 erg/s), which is perhaps the brightest X-ray source among the oldest pulsars still observable in the gamma-rays. Detailed timing and spectral analyses show strong evidence of an absorption feature (perhaps an electron cyclotron line) in the pulsar's spectrum. Characterizing its thermal emission might have important implications for the neutron star cooling models. Moving another two orders of magnitude up in characteristic age, we have one of the oldest known non-recycled X-ray pulsars, PSR J0108-3430, with characteristic age = 166 Myr and spin-down power = 5.8E30 erg/s. The pulsar's spectrum likely consists of a thermal component, emitted from a hot polar cap, and a non-thermal component, emitted from its magnetosphere. The X-ray pulse profile shows a single, asymmetric peak which could be explained by an axially-asymmetric temperature distribution at the pole or by the non-thermal emission from the outer gap. The three pulsars represent important stages in the evolutionary path that a hypothetical single young pulsar like J2022+3842 might take, as it passes through stages close to gamma-ray emission turn-off (like J1836+5925) and X-ray turn-off (similar to J0108-3430).Pulsars in binaries can follow an alternative path. By accreting matter from their companions they can be 'recycled' to short millisecond periods and emit X-rays and gamma-rays for billions of years. I also present a special class of such recycled pulsars which are believed to be in the process of fatally ablating their companions. I present the X-ray analysis of PSR J1446-4701, a pulsar with spin-down power = 3.6E34 erg/s in a 6.7 hr binary orbit, and PSR J1311-3430, a pulsar with spin-down power = 4.9E34 erg/s, in an extreme 1.6 hr binary orbit. PSR J1446-4701 turned out to be a non-eclipser with possibly low (face-on) orbital inclination, with emission from both the pulsar and the intra-binary shock observable throughout the binary orbit. PSR J1311-3430 is a known eclipser, in which we find hints of spectral variability between pulsar superior and inferior conjunction phases. I also present a comprehensive comparison of the sample of such extremely low-mass binary pulsars. We reveal the true nature of pulsars, slowly and steadily, usually one target at a time, but eventually we expect useful patterns to emerge that improves our understanding of the population of rotation powered pulsars.
Author: John A. Lowry Publisher: Nova Publishers ISBN: 9781594545672 Category : Science Languages : en Pages : 228
Book Description
Pulsars are stars, a significant part of whose observed energy output is not continuous but is emitted as distinct flashes or pulses of electromagnetic radiation. Many pulsars also emit some radiation weakly and constantly, forming a background for the more intensive pulses. Three distinct classes of pulsars are presently known to astronomers, according to the source of energy that powers the radiation: Rotation-powered pulsars, where the loss of rotational energy of the star powers the radiation X-ray pulsars, where the gravitational potential energy of accreted matter is the energy source, and Magnetars, where the decay of an extremely strong magnetic field powers the radiation. Although all three classes of objects are neutron stars, their observable behaviour and the underlying physics are quite different. There are, however, connections. For example, X-ray pulsars are probably old rotation-powered pulsars that have already lost most of their energy, and have only become visible again after their binary companions expanded and began transferring matter on to the neutron star. The process of accretion can in turn transfer enough angular momentum to the neutron star to "recycle" it as a rotation-powered millisecond pulsar.
Author: Sudip Bhattacharyya Publisher: Springer Nature ISBN: 3030851982 Category : Science Languages : en Pages : 334
Book Description
This book includes nine chapters written by internationally recognized experts, covering all aspects of millisecond pulsars in one concise and cohesive volume. These aspects include pulsations powered by stellar spin, accretion and thermonuclear burning of accreted matter, their physics and utility, stellar evolution and the extreme physics of super-dense stellar cores. The book includes substantial background material as well as recent theoretical and multi-wavelength observational results. The volume will thus be useful for professional astronomers and graduate students alike. What is the behavior of the strong nuclear interaction, and what are the matter constituents at ultrahigh densities in neutron star cores? How do old neutron stars in binaries evolve? How does their magnetosphere interact with the surrounding plasma to accelerate particles and emit radiation observed at all wavelengths? These are just a few of the questions that millisecond pulsars are helping us answer and will settle in the near future with the next generation of instruments. Such quickly rotating, highly magnetized neutron stars are remarkable natural laboratories that allow us to investigate the fundamental constituents of matter and their interactions under extreme conditions that cannot be reproduced in terrestrial laboratories.
Author: James J. Condon Publisher: Princeton University Press ISBN: 069113779X Category : Science Languages : en Pages : 376
Book Description
The ideal text for a one-semester course in radio astronomy Essential Radio Astronomy is the only textbook on the subject specifically designed for a one-semester introductory course for advanced undergraduates or graduate students in astronomy and astrophysics. It starts from first principles in order to fill gaps in students' backgrounds, make teaching easier for professors who are not expert radio astronomers, and provide a useful reference to the essential equations used by practitioners. This unique textbook reflects the fact that students of multiwavelength astronomy typically can afford to spend only one semester studying the observational techniques particular to each wavelength band. Essential Radio Astronomy presents only the most crucial concepts—succinctly and accessibly. It covers the general principles behind radio telescopes, receivers, and digital backends without getting bogged down in engineering details. Emphasizing the physical processes in radio sources, the book's approach is shaped by the view that radio astrophysics owes more to thermodynamics than electromagnetism. Proven in the classroom and generously illustrated throughout, Essential Radio Astronomy is an invaluable resource for students and researchers alike. The only textbook specifically designed for a one-semester course in radio astronomy Starts from first principles Makes teaching easier for astronomy professors who are not expert radio astronomers Emphasizes the physical processes in radio sources Covers the principles behind radio telescopes and receivers Provides the essential equations and fundamental constants used by practitioners Supplementary website includes lecture notes, problem sets, exams, and links to interactive demonstrations An online illustration package is available to professors
Author: Werner Becker Publisher: Springer Science & Business Media ISBN: 354076965X Category : Science Languages : en Pages : 702
Book Description
Neutron stars are the most compact astronomical objects in the universe which are accessible by direct observation. Studying neutron stars means studying physics in regimes unattainable in any terrestrial laboratory. Understanding their observed complex phenomena requires a wide range of scientific disciplines, including the nuclear and condensed matter physics of very dense matter in neutron star interiors, plasma physics and quantum electrodynamics of magnetospheres, and the relativistic magneto-hydrodynamics of electron-positron pulsar winds interacting with some ambient medium. Not to mention the test bed neutron stars provide for general relativity theories, and their importance as potential sources of gravitational waves. It is this variety of disciplines which, among others, makes neutron star research so fascinating, not only for those who have been working in the field for many years but also for students and young scientists. The aim of this book is to serve as a reference work which not only reviews the progress made since the early days of pulsar astronomy, but especially focuses on questions such as: "What have we learned about the subject and how did we learn it?", "What are the most important open questions in this area?" and "What new tools, telescopes, observations, and calculations are needed to answer these questions?". All authors who have contributed to this book have devoted a significant part of their scientific careers to exploring the nature of neutron stars and understanding pulsars. Everyone has paid special attention to writing educational comprehensive review articles with the needs of beginners, students and young scientists as potential readers in mind. This book will be a valuable source of information for these groups.
Author: John E. Deeter Publisher: ISBN: Category : Aeronautics Languages : en Pages :
Book Description
"The pulse-timing projects supported by NASA Grant NAG 8-695 were motivated in large part by our long-standing interest in the physics of rotating neutron stars and particularly the variations in rotation due to internal and external fluctuating torques. For accretion-powered pulsars, observed as compact galactic X-ray sources, our work has been motivated by questions regarding the physics of matter accretion, mass transfer and mass loss in these X-ray binary systems. For rotation-powered pulsars, using X-ray, optical and radio observations, we have examined the internal structure of neutron stars and mechanisms for secular spin-down. These issues are still central to the continuing process of understanding the complex behavior of these fascinating systems. The work supported by this grant is based mainly on Ginga observations of three pulsating X-ray sources. We observed two of these sources (Her X-1 and SMC X-1) within the framework of a NASA-ISAS program for U.S.-Japan collaborations to obtain and analyze Ginga observations. In addition, we joined with members of the Ginga team to apply our pulse-timing methods to PSR 0540-69 data obtained as a collateral benefit of the regular monitoring by Ginga of SN 1987A. In addition to these Ginga observations, there exist other relevant data on all three of these sources. The direction of our investigations has been affected by the necessity of including these supporting data in our analyses, and setting up the necessary collaborations has sometimes entailed extra work that was not anticipated in our proposals. Indeed, we have often taken the initiative in establishing these joint projects. Following is a brief summary of our efforts by individual sources."--Page 1.
Author: Rudy Wijnands Publisher: American Institute of Physics ISBN: 9780735405998 Category : Science Languages : en Pages : 274
Book Description
In X-ray binaries, neutron stars (the very dense stellar remnants of heavy stars) accrete matter from a close-by companion star. This matter eventually falls on the neutron star, significantly affecting it. I.e., the star is spun up to very high spin rates. In the end, it might rotate 1000 times a second which causes very fast oscillations in its X-ray brightness. This workshop was to celebrate the 10th anniversary of the discovery of the first system in which this signal was found and discuss the most recent observational and theoretical insight in the nature of these systems.
Author: Pranab Ghosh
Author: Pranab Ghosh
Author: Prakash Arumugasamy
Author: John A. Lowry
Author: Sudip Bhattacharyya
Author: James J. Condon
Author: Emre Tepedelenlioǧlu
Author: Werner Becker
Author: John E. Deeter
Author: Andrew Lyne
Author: Rudy Wijnands