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Pulse Timing Studies Of X Ray Pulsars
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Book Synopsis Pulse-timing Studies of X Ray Pulsars by : John E. Deeter
Download or read book Pulse-timing Studies of X Ray Pulsars written by John E. Deeter and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "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.
Book Synopsis X-ray Pulsar-based Navigation by : Wei Zheng
Download or read book X-ray Pulsar-based Navigation written by Wei Zheng and published by Springer Nature. This book was released on 2020-04-17 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses autonomous spacecraft navigation based on X-ray pulsars, analyzing how to process X-ray pulsar signals, how to simulate them, and how to estimate the pulse’s time of arrival based on epoch folding. In turn, the book presents a range of X-ray pulsar-based spacecraft positioning/time-keeping/attitude determination methods. It also describes the error transmission mechanism of the X-ray pulsar-based navigation system and its corresponding compensation methods. Further, the book introduces readers to navigation based on multiple measurement information fusion, such as X-ray pulsar/traditional celestial body integrated navigation and X-ray pulsar/INS integrated navigation. As such, it offers readers extensive information on both the theory and applications of X-ray pulsar-based navigation, and reflects the latest developments in China and abroad.
Book Synopsis Understanding X-ray Pulsars: from Blind Source Separation to Pulse Profile Decompositions by : Inga Saathoff
Download or read book Understanding X-ray Pulsars: from Blind Source Separation to Pulse Profile Decompositions written by Inga Saathoff and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In neutron star X-ray binaries, matter is transferred from the companion to the compact object where it encounters the strong magnetic field at the magnetosphere. The magnetic field redirects the material toward the magnetic poles, where it releases its gravitational potential energy mainly as X-rays. If the spin and magnetic axes are misaligned, this emission can be observed as pulsations, and the object is called an accreting X-ray pulsar. Folding the light curve, i.e. the intensity variation of the emission over time, with the spin period of the pulsar gives a pulse profile, which can have complex shapes due to the interplay of several factors such as geometry, magnetic field configuration, intrinsic beam patterns, and gravitational light bending. Understanding the physics of X-ray pulsars, and the extreme conditions that are associated with them, presents a number of challenges. Radiative transfer and the dynamical structure of the accretion flow must be modeled to gain insight into their complex nature. These problems are interrelated, since the properties and dynamics of the accreting matter directly affect the X-ray emission, and the resulting radiation pressure in turn changes the accretion flow. Such interactions play an important role in shaping the observed X-ray spectra and they are difficult to understand from both a theoretical and observational point of view. In addition, the emission that escapes from the immediate vicinity of the surface of the neutron star is not necessarily what is observed: during different phases of the star's rotation, emission from both poles may be observed simultaneously due to phenomena such as gravitational light bending. To test and refine models describing the formation of spectra and pulse profiles in X-ray pulsars, it is necessary to determine the contributions of each pole to the observed flux as a function of phase, which helps to study the physical processes involved in radiative transfer. The rotation of the pulsar makes it possible to study the angular dependence of the emission, which in turn contributes to a better understanding of the physics of X-ray pulsars. To accomplish this, a new data-driven approach is used in this thesis that takes advantage of the pulse-to-pulse variability in the observed flux. The method is based on treating the task as a blind source separation problem, where the goal is to estimate unknown signals mixed with unknown mixing coefficients. In this context, blind source separation techniques can be used by exploiting the inherent flux variability that is partially independent for the two poles. The result of this decomposition are the two signals representing the time variability of the accretion rate at each pole and the weights associated with each pole. These weights are the single-pole pulse profiles of interest. To establish the method, in this thesis I develop the phase correlated variability analysis (PCVA) through a series of simulations. This includes determining the requirements and limitations of the PCVA to ensure its effectiveness in disentangling the contributions of the two poles in X-ray pulsars. I then demonstrate the application of the PCVA to observational data of the bright persistent X-ray pulsar Cen X-3 obtained from RXTE (Rossi X-ray Timing Explorer) observations. I compare the results obtained with the PCVA to those of previous studies that have addressed the same problem. Based on my results, I find that the symmetry assumption made in the past is incompatible with the PCVA results and thus may not be justified. In order to interpret the results of the PCVA, I create a toy model to describe the obtained pulse profiles. This model is based on a number of assumptions. First, the geometry of the system is defined by considering the inclination and position angle of the pulsar spin. The emission region is assumed to be generated by a single source at each pole. To introduce asymmetry, a phenomenological beam pattern is defined that is symmetric about a certain direction but asymmetric with respect to the normal of the surface. This results in asymmetric beam patterns due to the rotation of the neutron star. The toy model also allows for an offset of the dipole as an additional parameter and incorporates the effects of gravitational light bending. In this way, the model provides a means to study the effect of different parameters, most importantly the intrinsic beam pattern, on the observed pulse profiles from each pole. I then address the Cen X-3 PCVA result in the context of the toy model. Despite accounting for gravitational light bending, the presence of mostly non-zero contributions throughout the rotation makes it difficult to find a solution using literature geometry. I find a slight improvement by allowing for an offset of the dipole, but the visibility problem still remains and I discuss possible solutions to this problem. One possibility is to relax the basic pulsar geometry, since all methods for determining the geometry are based on models or assumptions that are not absolute. Alternatively, the use of a more complex beam pattern model or the consideration of extended emission regions could potentially resolve the lack of visibility gaps in the results. The PCVA developed in this thesis allows the separation of the emission contributions from the two poles of X-ray pulsars. In principle, this method can be applied to any luminous X-ray pulsar, provided that the specified source and observational requirements are met. Thus, by studying the individual contributions from each pole, the PCVA allows the study of changes in the accretion process and structures. In addition, the toy model provides a tool for exploring various parameters that shape the pulse profile, in particular the effects of a slightly asymmetric beam pattern.
Book Synopsis Pulse Timing Techniques and Applications to X-ray Pulsars by : John Emerson Deeter
Download or read book Pulse Timing Techniques and Applications to X-ray Pulsars written by John Emerson Deeter and published by . This book was released on 1981 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Essential Radio Astronomy by : James J. Condon
Download or read book Essential Radio Astronomy written by James J. Condon and published by Princeton University Press. This book was released on 2016-04-05 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Book Synopsis Rotation and Accretion Powered Pulsars by : Pranab Ghosh
Download or read book Rotation and Accretion Powered Pulsars written by Pranab Ghosh and published by World Scientific. This book was released on 2007 with total page 793 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Neutron Stars and Pulsars by : Werner Becker
Download or read book Neutron Stars and Pulsars written by Werner Becker and published by Springer Science & Business Media. This book was released on 2009-02-11 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Navigation in Space by X-ray Pulsars by : Amir Abbas Emadzadeh
Download or read book Navigation in Space by X-ray Pulsars written by Amir Abbas Emadzadeh and published by Springer Science & Business Media. This book was released on 2011-02-26 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Pulsar Astronomy written by Andrew Lyne and published by Cambridge University Press. This book was released on 2012-03 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: Now in its fourth edition, Pulsar Astronomy provides a thoroughly revised and updated introduction to the field of pulsar astronomy.
Book Synopsis Highlights of Spanish Astrophysics V by : Jose M. Diego
Download or read book Highlights of Spanish Astrophysics V written by Jose M. Diego and published by Springer Science & Business Media. This book was released on 2010-03-18 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy is a scienti?c discipline that has developed a rapid and impressive growth in Spain. Thirty years ago, Spain occupied a purely anecdotal presence in the international context, but today it occupies the eighth position in the world in publication of astronomical articles, and, among other successes, owns and op- ates ninety per cent of the world’s largest optical telescope GTC (Gran Telescopio Canarias). The Eighth Scienti?c Meeting of the Spanish Astronomical Society (Sociedad Espanol ̃ a de Astronom ́ a, SEA), held in Santander in July 7–11 2008, whose p- ceedings are in your hands, clearly shows the enthusiasm, motivation and quality of the present Spanish astronomical community. The event brought together 322 participants, who represent almost 50% of Spanish professional astronomers. This percentage, together with the continuously increasing, with respect to previous SEA meetings, number of oral presentations and poster contributions (179 and 127 respectively), con?rms that the SEA conferences have become a point of reference to assess the interests and achievements of astrophysical research in Spain. The most important and current topics of modern Astrophysics were taken into accountat thepreliminarymeeting,aswell as the numberandqualityofparticipants and their contributions, to select the invited speakers and oral contributors. We took a week to enjoy the high quality contributions submitted by Spanish astronomers to the Scienti?c Organizing Committee. The selection was dif?cult. We wish to acknowledge the gentle advice and commitment of the SOC members.
Book Synopsis Long-term Monitoring of Anomalous X-ray Pulsars with the Rossi X-ray Timing Explorer by : Fotis P. Gavriil
Download or read book Long-term Monitoring of Anomalous X-ray Pulsars with the Rossi X-ray Timing Explorer written by Fotis P. Gavriil and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "We report on the long-term monitoring of five anomalous X-ray Pulsars (AXPs) using the Rossi X-ray Timing Explorer (RXTE ). We present a phase-coherent timing ephemeris for 4U 0142+61, and show that it has rotated with high stability over 4.4 yr, with RMS phase deviation of 7% of the pulse period from a simple fit including only n and n&d2; . We show that 1E 1048.1-5937 shows significant deviations from simple spin-down such that phase-coherent timing has not been possible over time spans longer than a few months. We find that the deviations from simple spin down are not consistent with single "glitch" type events, nor are they consistent with radiative precession. We suggest that 1E 1048.1-5937 may be a transition object between the soft gamma-ray repeater and AXP populations, and the AXP most likely to one day undergo an outburst. We also report on the continued timing stability of 1E 2259.1+586, for which phase coherence has now been maintained over 4.5 yr, as well as on the detection of a significant n&d3; in RXS J170849.0-400910, consistent with recovery following a glitch. We note a possible correlation in which timing stability decreases with increasing n&d2; . We find no large variability in pulse morphology as a function of time. We present high signal-to-noise ratio average pulse profiles for each AXP, and consider them as a function of energy. We find a variety of different behaviors, and consider possible trends in the data. We also find no large variations in pulsed flux, and set la upper limits of ∼20--30% of the mean." --
Author :Fotis P. (Fotis Panagiotis) Gavriil Publisher :National Library of Canada = Bibliothèque nationale du Canada ISBN 13 :9780612788800 Total Pages : pages Book Rating :4.7/5 (888 download)
Book Synopsis Long-term Monitoring of Anomalous X-ray Pulsars with the Rossi X-ray Timing Explorer [microform] by : Fotis P. (Fotis Panagiotis) Gavriil
Download or read book Long-term Monitoring of Anomalous X-ray Pulsars with the Rossi X-ray Timing Explorer [microform] written by Fotis P. (Fotis Panagiotis) Gavriil and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "We report on the long-term monitoring of five anomalous X-ray Pulsars (AXPs) using the Rossi X-ray Timing Explorer (RXTE ). We present a phase-coherent timing ephemeris for 4U 0142+61, and show that it has rotated with high stability over 4.4 yr, with RMS phase deviation of 7% of the pulse period from a simple fit including only n and n&d2; . We show that 1E 1048.1-5937 shows significant deviations from simple spin-down such that phase-coherent timing has not been possible over time spans longer than a few months. We find that the deviations from simple spin down are not consistent with single "glitch" type events, nor are they consistent with radiative precession. We suggest that 1E 1048.1-5937 may be a transition object between the soft gamma-ray repeater and AXP populations, and the AXP most likely to one day undergo an outburst. We also report on the continued timing stability of 1E 2259.1+586, for which phase coherence has now been maintained over 4.5 yr, as well as on the detection of a significant n&d3; in RXS J170849.0-400910, consistent with recovery following a glitch. We note a possible correlation in which timing stability decreases with increasing n&d2; . We find no large variability in pulse morphology as a function of time. We present high signal-to-noise ratio average pulse profiles for each AXP, and consider them as a function of energy. We find a variety of different behaviors, and consider possible trends in the data. We also find no large variations in pulsed flux, and set la upper limits of ∼20--30% of the mean." --
Book Synopsis Handbook of Pulsar Astronomy by : D. R. Lorimer
Download or read book Handbook of Pulsar Astronomy written by D. R. Lorimer and published by Cambridge University Press. This book was released on 2005 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 2004 book provides a concise description of pulsar research, presenting key techniques, background information and results.
Book Synopsis Rotation Powered Pulsars in the X-rays by : Prakash Arumugasamy
Download or read book Rotation Powered Pulsars in the X-rays written by Prakash Arumugasamy and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Timing Young Pulsars by : Margaret Anne Livingstone
Download or read book Timing Young Pulsars written by Margaret Anne Livingstone and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis X-ray Timing of the Accreting Millisecond Pulsar SAX J1808.4-3658 by : Jacob M. Hartman (Ph. D.)
Download or read book X-ray Timing of the Accreting Millisecond Pulsar SAX J1808.4-3658 written by Jacob M. Hartman (Ph. D.) and published by . This book was released on 2007 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a 7 yr timing study of the 2.5 ms X-ray pulsar SAX J1808.4-3658, an X-ray transient with a recurrence time of =2 yr, using data from the Rossi X-ray Timing Explorer covering 4 transient outbursts (1998-2005). Substantial pulse shape variability, both stochastic and systematic, was observed during each outburst. Analysis of the systematic pulse shape changes suggests that, as an outburst dims, the X-ray "hot spot" on the pulsar surface drifts longitudinally and a second hot spot may appear. The overall pulse shape variability limits the ability to measure spin frequency evolution within a given X-ray outburst (and calls previous zi measurements of this source into question), with typical upper limits of Jil
Book Synopsis X-Ray Binaries and Recycled Pulsars by : E.P. van den Heuvel
Download or read book X-Ray Binaries and Recycled Pulsars written by E.P. van den Heuvel and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
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