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Author: Pranab Ghosh
Publisher: World Scientific
ISBN: 9810247443
Category : Science
Languages : en
Pages : 793
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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
Get Book Here
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 :
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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: Emre Tepedelenlioǧlu
Publisher:
ISBN:
Category :
Languages : en
Pages : 126
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Book Description
Author: Li Zhang
Publisher: Open Dissertation Press
ISBN: 9781374723597
Category : Science
Languages : en
Pages : 150
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Book Description
This dissertation, "High Energy Radiation From Rotation-powered Pulsars" by Li, Zhang, 張力, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of Thesis entitled HIGH ENERGY RADIATION FROM ROTATION-POWERED PULSARS Submitted by ZHANG LI for the Degree of Doctor of Philosophy at The University of Hong Kong in May 1998. Motivated by the observations of high energy radiations from pulsars by ROSAT and ASCA satellites (X-ray energy range), and the Energetic Gamma Ray Experiment Tele- scope (EGRET) on board the Compton Gamma Ray Observatory (CGRO) (7-ray energy range), we have revisited the theory of high energy radiations from rotation-powered pulsars. We propose a self-consistent outer gap model to describe high energy radiations from the rotation-powered pulsars. In this model, X-rays from the pulsar consist of thermal X- rays which originate from the stellar surface and non-thermal X-rays which are produced by synchrotron radiation of secondary electrons/positrons backflowing to the star from the outer gap. The high energy 7-rays are produced by the synchro-curvature mechanism from the outer gap. This model explains successfully the X-ray observations from the pulsars and the high energy 7-ray spectra from the known 7-ray pulsars except for the Crab pulsar.It also explains not only the efficiency of the known 7-ray pulsars but also why the 7-ray efficiency of millisecond pulsars is so low. Based on this model, the properties of the Galactic population of rotation-powered pulsars are simulated by using Monte Carlo methods. The following results have been obtained: (i) there may be 11 7-ray pulsars which are detectable at both radio and 7-ray energies and 37 Geminga-like pulsars; (ii) the majority of the unidentified EGRET 7- ray point sources near the Galactic plane may consist of Geminga-like pulsars and the most likely parameter range for Geminga-like pulsars is P = 0.1 - 0.3 seconds and B\2 = 0.8 - 5 with constraint 5.5P26/215 DEGREES DOI: 10.5353/th_b3008817 Subjects: Pulsars
Author: Amir Abbas Emadzadeh
Publisher: Springer Science & Business Media
ISBN: 1441980172
Category : Technology & Engineering
Languages : en
Pages : 126
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Book Description
Navigation in Space by X-ray Pulsars will consist of two parts. One is on modeling of X-ray pulsar signals. The second part explains how X-ray pulsar signals can be used to solve the relative navigation problem. This book formulates the problem, proposes a recursive solution, and analyzes different aspects of the navigation system. This book will be a comprehensive source for researchers. It provides new research results on signal processing techniques needed for X-ray pulsar based navigation in deep space.
Author: John A. Lowry
Publisher: Nova Publishers
ISBN: 9781594545672
Category : Science
Languages : en
Pages : 228
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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: E.P. van den Heuvel
Publisher: Springer Science & Business Media
ISBN: 9401127042
Category : Science
Languages : en
Pages : 545
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Book Description
Proceedings of the NATO Advanced Research Workshop on X-Ray Binaries and the Formation of Binary and Millisecond Radio Pulsars, Santa Barbara, CA, U.S.A., Januari 21-25, 1991
Author: Sudip Bhattacharyya
Publisher: Springer Nature
ISBN: 3030851982
Category : Science
Languages : en
Pages : 334
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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: Rudy Wijnands
Publisher: American Institute of Physics
ISBN: 9780735405998
Category : Science
Languages : en
Pages : 274
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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
Publisher: World Scientific
ISBN: 9814490148
Category : Science
Languages : en
Pages : 793
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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.
