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The aim of the inaugural meeting of the Sant Cugat Forum on Astrophysics was to address, in a global context, the current understanding of and challenges in high-energy emissions from isolated and non-isolated neutron stars, and to confront the theoretical picture with observations of both the Fermi satellite and the currently operating ground-based Cherenkov telescopes. Participants have also discussed the prospects for possible observations with planned instruments across the multi-wavelength spectrum (e.g. SKA, LOFAR, E-VLT, IXO, CTA) and how they will impact our theoretical understanding of these systems. In keeping with the goals of the Forum, this book not only represents the proceedings of the meeting, but also a reflection on the state-of-the-art in the topic.
Book Synopsis High-Energy Emission from Pulsars and their Systems by : Nanda Rea
Download or read book High-Energy Emission from Pulsars and their Systems written by Nanda Rea and published by Springer Science & Business Media. This book was released on 2011-02-04 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of the inaugural meeting of the Sant Cugat Forum on Astrophysics was to address, in a global context, the current understanding of and challenges in high-energy emissions from isolated and non-isolated neutron stars, and to confront the theoretical picture with observations of both the Fermi satellite and the currently operating ground-based Cherenkov telescopes. Participants have also discussed the prospects for possible observations with planned instruments across the multi-wavelength spectrum (e.g. SKA, LOFAR, E-VLT, IXO, CTA) and how they will impact our theoretical understanding of these systems. In keeping with the goals of the Forum, this book not only represents the proceedings of the meeting, but also a reflection on the state-of-the-art in the topic.
This book reports on the extraordinary observation of TeV gamma rays from the Crab Pulsar, the most energetic light ever detected from this type of object. It presents detailed information on the painstaking analysis of the unprecedentedly large dataset from the MAGIC telescopes, and comprehensively discusses the implications of pulsed TeV gamma rays for state-of-the-art pulsar emission models. Using these results, the book subsequently explores new testing methodologies for Lorentz Invariance Violation, in terms of a wavelength-dependent speed of light. The book also covers an updated search for Very-High-Energy (VHE), >100 GeV, emissions from millisecond pulsars using the Large Area Telescope on board the Fermi satellite, as well as a study on the promising Pulsar Wind Nebula candidate PSR J0631. The observation of VHE gamma rays is essential to studying the non-thermal sources of radiation in our Universe. Rotating neutron stars, also known as pulsars, are an extreme source class known to emit VHE gamma rays. However, to date only two pulsars have been detected with emissions above 100 GeV, and our understanding of their emission mechanism is still lacking.
Book Synopsis Revealing the Most Energetic Light from Pulsars and Their Nebulae by : David Carreto Fidalgo
Download or read book Revealing the Most Energetic Light from Pulsars and Their Nebulae written by David Carreto Fidalgo and published by Springer. This book was released on 2019-07-17 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports on the extraordinary observation of TeV gamma rays from the Crab Pulsar, the most energetic light ever detected from this type of object. It presents detailed information on the painstaking analysis of the unprecedentedly large dataset from the MAGIC telescopes, and comprehensively discusses the implications of pulsed TeV gamma rays for state-of-the-art pulsar emission models. Using these results, the book subsequently explores new testing methodologies for Lorentz Invariance Violation, in terms of a wavelength-dependent speed of light. The book also covers an updated search for Very-High-Energy (VHE), >100 GeV, emissions from millisecond pulsars using the Large Area Telescope on board the Fermi satellite, as well as a study on the promising Pulsar Wind Nebula candidate PSR J0631. The observation of VHE gamma rays is essential to studying the non-thermal sources of radiation in our Universe. Rotating neutron stars, also known as pulsars, are an extreme source class known to emit VHE gamma rays. However, to date only two pulsars have been detected with emissions above 100 GeV, and our understanding of their emission mechanism is still lacking.
This dissertation, "High-energy Radiation From Millisecond Pulsars" by Man-ho, Wu, 胡文浩, 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: As the successor of the Energetic Gamma Ray Experiment Telescope, the Large Area Telescope on board the Fermi Gamma-ray Space Telescope has measured the pulsations from over a hundred pulsars, a rapidly growing population in the gamma-ray sky. Pulsars spinning as fast as a few to ten milliseconds, the millisecond pulsars (MSPs), constitute over 30% of the population, with most of which found in binary systems. Many MSPs are found to have low-mass companions with masses less than 0:1 of that of the Sun. Observations reveal that in these systems, the companion is irradiated by the radiation and/or the wind from the pulsar. It is believed that isolated MSPs in the Galactic field were once a member of such kind of systems, and have ablated their companion away. The gamma-ray emission from the original Black Widow pulsar was studied using data from the Fermi-LAT. The emission was found to depend on the orbital phase and an extra higher-energy component was observed near the inferior conjunction. The results can be explained by an inverse Compton (IC) process associated with the ultra-relativistic pulsar wind. PSR B1957+20 is the first black widow system from which evidence on interaction of unshocked pulsar wind is observed. In addition, diffuse X-rays were found from the globular cluster (GC) 47 Tucanae. It is believed that the observed gamma-rays and the diffuse X-rays can be produced via inverse Compton process between the background soft photons and the pulsar wind from the MSPs residing in the GC. The observation of diffuse X-rays from 47 Tucanae provides constraints on the energetics and the emission region for the IC scenario. They provide good examples and guides for search strategies of similar emissions in other black widow systems and globular clusters. DOI: 10.5353/th_b5108703 Subjects: Pulsars
Book Synopsis High-Energy Radiation from Millisecond Pulsars by : Man-Ho Wu
Download or read book High-Energy Radiation from Millisecond Pulsars written by Man-Ho Wu and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "High-energy Radiation From Millisecond Pulsars" by Man-ho, Wu, 胡文浩, 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: As the successor of the Energetic Gamma Ray Experiment Telescope, the Large Area Telescope on board the Fermi Gamma-ray Space Telescope has measured the pulsations from over a hundred pulsars, a rapidly growing population in the gamma-ray sky. Pulsars spinning as fast as a few to ten milliseconds, the millisecond pulsars (MSPs), constitute over 30% of the population, with most of which found in binary systems. Many MSPs are found to have low-mass companions with masses less than 0:1 of that of the Sun. Observations reveal that in these systems, the companion is irradiated by the radiation and/or the wind from the pulsar. It is believed that isolated MSPs in the Galactic field were once a member of such kind of systems, and have ablated their companion away. The gamma-ray emission from the original Black Widow pulsar was studied using data from the Fermi-LAT. The emission was found to depend on the orbital phase and an extra higher-energy component was observed near the inferior conjunction. The results can be explained by an inverse Compton (IC) process associated with the ultra-relativistic pulsar wind. PSR B1957+20 is the first black widow system from which evidence on interaction of unshocked pulsar wind is observed. In addition, diffuse X-rays were found from the globular cluster (GC) 47 Tucanae. It is believed that the observed gamma-rays and the diffuse X-rays can be produced via inverse Compton process between the background soft photons and the pulsar wind from the MSPs residing in the GC. The observation of diffuse X-rays from 47 Tucanae provides constraints on the energetics and the emission region for the IC scenario. They provide good examples and guides for search strategies of similar emissions in other black widow systems and globular clusters. DOI: 10.5353/th_b5108703 Subjects: Pulsars
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.
Book Synopsis Millisecond Pulsars by : Sudip Bhattacharyya
Download or read book Millisecond Pulsars written by Sudip Bhattacharyya and published by Springer Nature. This book was released on 2022-03-15 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
For several decades, since their discovery in 1967 by Jocelyn Bell Burnell, pulsars have been under intense investigation. Due to their huge magnetic and gravitational elds, pulsars are one of the best laboratories to study matter in extreme conditions. Recently, the detection of emission from the Crab pulsar at Very High Energies (VHE, > 100 GeV) was a breakthrough, as such emission was totally unexpected. Even though pulsars are being deeply studied, their emission location and mechanisms are still poorly understood. Several regions where the VHE gamma rays are expected to be emitted where proposed, each of them exhibiting di erent features in the pulsars emission, such as energy spectrum and light curve properties. The observation of pulsars at VHE is then fundamental in order to understand their emission properties and distinguish between the current models. This thesis deals with the characterization of the VHE emission from pulsars. This study relies on the observations of pulsars with the MAGIC telescopes and the analytic calculation of the pulsar X-ray and gamma-ray emission e ciencies in the framework of the outer-gap model. Two pulsars were selected for the observations with the MAGIC telescopes, namely, the Crab and Geminga pulsars. These pulsars are the two brightest gamma-ray pulsars observable from the Northern Hemisphere. The study of the Crab pulsar revealed the signi cant emission from the interpulse region, also called bridge, located between the two main peaks. This component, already observed at low energies and predicted at VHE, was not previously detected at VHE. Furthermore, the relative emission between the two main peaks and the bridge was computed, including the analysis of 6.5 years of Fermi-LAT data. The behaviors of P2/P1 and bridge/P1 revealed a similar trend, unveiling similar properties in the emission of these distinct components...
Book Synopsis Characterization of the Very-high-energy Emission from Pulsars with the Magic Telescopes by : Simon Bonnefoy
Download or read book Characterization of the Very-high-energy Emission from Pulsars with the Magic Telescopes written by Simon Bonnefoy and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For several decades, since their discovery in 1967 by Jocelyn Bell Burnell, pulsars have been under intense investigation. Due to their huge magnetic and gravitational elds, pulsars are one of the best laboratories to study matter in extreme conditions. Recently, the detection of emission from the Crab pulsar at Very High Energies (VHE, > 100 GeV) was a breakthrough, as such emission was totally unexpected. Even though pulsars are being deeply studied, their emission location and mechanisms are still poorly understood. Several regions where the VHE gamma rays are expected to be emitted where proposed, each of them exhibiting di erent features in the pulsars emission, such as energy spectrum and light curve properties. The observation of pulsars at VHE is then fundamental in order to understand their emission properties and distinguish between the current models. This thesis deals with the characterization of the VHE emission from pulsars. This study relies on the observations of pulsars with the MAGIC telescopes and the analytic calculation of the pulsar X-ray and gamma-ray emission e ciencies in the framework of the outer-gap model. Two pulsars were selected for the observations with the MAGIC telescopes, namely, the Crab and Geminga pulsars. These pulsars are the two brightest gamma-ray pulsars observable from the Northern Hemisphere. The study of the Crab pulsar revealed the signi cant emission from the interpulse region, also called bridge, located between the two main peaks. This component, already observed at low energies and predicted at VHE, was not previously detected at VHE. Furthermore, the relative emission between the two main peaks and the bridge was computed, including the analysis of 6.5 years of Fermi-LAT data. The behaviors of P2/P1 and bridge/P1 revealed a similar trend, unveiling similar properties in the emission of these distinct components...
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 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
This book is a collation of the contributions presented at a major conference on isolated neutron stars held in London in April 2006. Forty years after the discovery of radio pulsars it presents an up-to-date description of the new vision of isolated neutron stars that has emerged in recent years. The great variety of isolated neutron stars, from pulsars to magnetars, is well covered by descriptions of recent observational results and presentations of the latest theoretical interpretation of these data.
Book Synopsis Isolated Neutron Stars: From the Surface to the Interior by : Silvia Zane
Download or read book Isolated Neutron Stars: From the Surface to the Interior written by Silvia Zane and published by Springer Science & Business Media. This book was released on 2007-05-22 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a collation of the contributions presented at a major conference on isolated neutron stars held in London in April 2006. Forty years after the discovery of radio pulsars it presents an up-to-date description of the new vision of isolated neutron stars that has emerged in recent years. The great variety of isolated neutron stars, from pulsars to magnetars, is well covered by descriptions of recent observational results and presentations of the latest theoretical interpretation of these data.
This dissertation, "Gamma-ray Emissions From Pulsar Binaries" by Chun-kwan, Leung, 梁晉堃, 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: The launch of the Fermi Gamma-ray Space Telescope marked a new era in observing gamma-rays from astrophysical sources. Fermi's high sensitivity in the 0.1-300GeV energy range opens an important window in the observation of the gamma-ray emissions from pulsar binaries, which emit most of their radiation energy in the gamma-ray range. We can now observe the gamma-ray emissions from pulsar binaries at an unprecedented accuracy, and investigate their origin in detail. In this thesis, we present the studies on two systems of pulsar binary of two distinct classes. The gamma-ray emissions from the high-mass gamma-ray binary LS 5039 were studied using the latest data from Fermi. The emission is modulated according to the 3.9 hr orbital period of the system. The results can be explained by the contribution of three components: the pulsar magnetospheric emission, the pulsar wind emission and the emissions from the shock formed from the interaction between the pulsar wind and companion's stellar wind. The results were compared with observed data from Fermi and also in X-ray and TeV. In addition, the emissions from the millisecond pulsar PSR J1023+0038 and its low mass binary companion were also studied. This system recently went through a transition from the rotation-powered state to the accretion state, after going the opposite way in 2007. This state transition, discovered through the disappearance of radio pulsation, was accompanied by the brightening in GeV, X-ray and UV fluxes. A detailed Fermi observation was performed, supplemented by multi-wavelength observations. It was found that the emission from this system can also be described by the emissions from the pulsar magnetosphere, the pulsar wind and its shock. These two systems, although of distinct classes of pulsar binaries, provide complementary cases for the study of high-energy radiation processes in pulsar binaries. DOI: 10.5353/th_b5317064 Subjects: Gamma ray astronomy Pulsars
Book Synopsis Gamma-Ray Emissions from Pulsar Binaries by : Chun-Kwan Leung
Download or read book Gamma-Ray Emissions from Pulsar Binaries written by Chun-Kwan Leung and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Gamma-ray Emissions From Pulsar Binaries" by Chun-kwan, Leung, 梁晉堃, 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: The launch of the Fermi Gamma-ray Space Telescope marked a new era in observing gamma-rays from astrophysical sources. Fermi's high sensitivity in the 0.1-300GeV energy range opens an important window in the observation of the gamma-ray emissions from pulsar binaries, which emit most of their radiation energy in the gamma-ray range. We can now observe the gamma-ray emissions from pulsar binaries at an unprecedented accuracy, and investigate their origin in detail. In this thesis, we present the studies on two systems of pulsar binary of two distinct classes. The gamma-ray emissions from the high-mass gamma-ray binary LS 5039 were studied using the latest data from Fermi. The emission is modulated according to the 3.9 hr orbital period of the system. The results can be explained by the contribution of three components: the pulsar magnetospheric emission, the pulsar wind emission and the emissions from the shock formed from the interaction between the pulsar wind and companion's stellar wind. The results were compared with observed data from Fermi and also in X-ray and TeV. In addition, the emissions from the millisecond pulsar PSR J1023+0038 and its low mass binary companion were also studied. This system recently went through a transition from the rotation-powered state to the accretion state, after going the opposite way in 2007. This state transition, discovered through the disappearance of radio pulsation, was accompanied by the brightening in GeV, X-ray and UV fluxes. A detailed Fermi observation was performed, supplemented by multi-wavelength observations. It was found that the emission from this system can also be described by the emissions from the pulsar magnetosphere, the pulsar wind and its shock. These two systems, although of distinct classes of pulsar binaries, provide complementary cases for the study of high-energy radiation processes in pulsar binaries. DOI: 10.5353/th_b5317064 Subjects: Gamma ray astronomy Pulsars
This dissertation, "Model of High Energy Emission From Young Pulsars" by Shimin, Zhang, 張世民, 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: Edited by Foxit PDF Editor Copyright (c) by Foxit Software Company, 2004 - 2007 For Evaluation Only. Abstract of thesis entitled MODEL OF HIGH ENERGY EMISSION FROM YOUNG PULSARS submitted by Zhang Shimin for the Degree of Master of Philosophy at The University of Hong Kong in February 2008 The Vela pulsar, PSR B0833-45, is the brightest 100 MeV γ-ray pulsar in the sky. It is the prototype of the young Vela-like pulsars with a characteristic age of 10 years, sometimes called "middle-aged" compared with Crab-like pulsars. In this thesis, a modified three dimensional thick outer gap model was used to explain the magnetosphere geometry, the light curve and the phase-resolved high energy spectra in γ-ray band of the Vela pulsar. As outer gap grows, it becomes more powerful and produce more e pairs, which can prevent the gap to expand further. Therefore it is believed that pulsars should have self-sustained thick outer gap and are stable γ-ray emitters. Taking into account the three-dimensional structure of pulsar magnetosphere, we can show a theoretical double-peak pattern of Vela light curve, which is consistent with observations. In the numerical simulation, only two parameters were needed, the inclination angle and the viewing angle, and they were chosen ◦ ◦ to be 65 and 83 in the thesis. We set the intersection of null charge surface and last closed field lines as the inner boundary of the outer gap and the outer boundary was assumed to be the light cylinder. In this gap geometry, only the light curve within two peaks can be reproduced. However, most γ-rays from the Vela pulsar indeed concentrated between the two peaks. The γ-ray emissions of Vela pulsar were supposed due to curvature radiation of primary e pairs mainly outgoing in open field regions. The phase-resolved spectra depend on many factors in the magnetosphere such as local accelerating electric field and local curvature radius of magnetic field, which are sensitive to radial distance. For given magnetic inclination angle and viewing angle, we can calculate the spectrum at different radial distances. The spectra produced in each radial distance of the emission region were summed up to obtain the total spectrum of curvature radiation. From 30 MeV to 2 GeV, the spectra fit well with data from EGRET. Some basic properties of pulsars and various theoretical models were also reviewed in the thesis. DOI: 10.5353/th_b3970745 Subjects: Pulsars
Book Synopsis Model of High Energy Emission from Young Pulsars by : Shimin Zhang
Download or read book Model of High Energy Emission from Young Pulsars written by Shimin Zhang and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Model of High Energy Emission From Young Pulsars" by Shimin, Zhang, 張世民, 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: Edited by Foxit PDF Editor Copyright (c) by Foxit Software Company, 2004 - 2007 For Evaluation Only. Abstract of thesis entitled MODEL OF HIGH ENERGY EMISSION FROM YOUNG PULSARS submitted by Zhang Shimin for the Degree of Master of Philosophy at The University of Hong Kong in February 2008 The Vela pulsar, PSR B0833-45, is the brightest 100 MeV γ-ray pulsar in the sky. It is the prototype of the young Vela-like pulsars with a characteristic age of 10 years, sometimes called "middle-aged" compared with Crab-like pulsars. In this thesis, a modified three dimensional thick outer gap model was used to explain the magnetosphere geometry, the light curve and the phase-resolved high energy spectra in γ-ray band of the Vela pulsar. As outer gap grows, it becomes more powerful and produce more e pairs, which can prevent the gap to expand further. Therefore it is believed that pulsars should have self-sustained thick outer gap and are stable γ-ray emitters. Taking into account the three-dimensional structure of pulsar magnetosphere, we can show a theoretical double-peak pattern of Vela light curve, which is consistent with observations. In the numerical simulation, only two parameters were needed, the inclination angle and the viewing angle, and they were chosen ◦ ◦ to be 65 and 83 in the thesis. We set the intersection of null charge surface and last closed field lines as the inner boundary of the outer gap and the outer boundary was assumed to be the light cylinder. In this gap geometry, only the light curve within two peaks can be reproduced. However, most γ-rays from the Vela pulsar indeed concentrated between the two peaks. The γ-ray emissions of Vela pulsar were supposed due to curvature radiation of primary e pairs mainly outgoing in open field regions. The phase-resolved spectra depend on many factors in the magnetosphere such as local accelerating electric field and local curvature radius of magnetic field, which are sensitive to radial distance. For given magnetic inclination angle and viewing angle, we can calculate the spectrum at different radial distances. The spectra produced in each radial distance of the emission region were summed up to obtain the total spectrum of curvature radiation. From 30 MeV to 2 GeV, the spectra fit well with data from EGRET. Some basic properties of pulsars and various theoretical models were also reviewed in the thesis. DOI: 10.5353/th_b3970745 Subjects: Pulsars
Now in its fourth edition, Pulsar Astronomy provides a thoroughly revised and updated introduction to the field of pulsar astronomy.
Book Synopsis Pulsar Astronomy by : Andrew Lyne
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.
