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Author: Anatoly Spitkovsky
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Magnetospheres of many astrophysical objects can be accurately described by the low-inertia (or ''force-free'') limit of MHD. We present a new numerical method for solution of equations of force-free relativistic MHD based on the finite-difference time-domain (FDTD) approach with a prescription for handling spontaneous formation of current sheets. We use this method to study the time-dependent evolution of pulsar magnetospheres in both aligned and oblique magnetic geometries. For the aligned rotator we confirm the general properties of the time-independent solution of Contopoulos et al. (1999). For the oblique rotator we present the 3D structure of the magnetosphere and compute, for the first time, the spindown power of pulsars as a function of inclination of the magnetic axis. We find the pulsar spindown luminosity to be L {approx} ({mu}{sup 2}{Omega}{sub *}{sup 4}/c{sup 3})(1 + sin{sup 2}{alpha}) for a star with the dipole moment {mu}, rotation frequency {Omega}{sub *}, and magnetic inclination angle {alpha}. We also discuss the effects of current sheet resistivity and reconnection on the structure and evolution of the magnetosphere.
Author: Anatoly Spitkovsky
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Magnetospheres of many astrophysical objects can be accurately described by the low-inertia (or ''force-free'') limit of MHD. We present a new numerical method for solution of equations of force-free relativistic MHD based on the finite-difference time-domain (FDTD) approach with a prescription for handling spontaneous formation of current sheets. We use this method to study the time-dependent evolution of pulsar magnetospheres in both aligned and oblique magnetic geometries. For the aligned rotator we confirm the general properties of the time-independent solution of Contopoulos et al. (1999). For the oblique rotator we present the 3D structure of the magnetosphere and compute, for the first time, the spindown power of pulsars as a function of inclination of the magnetic axis. We find the pulsar spindown luminosity to be L {approx} ({mu}{sup 2}{Omega}{sub *}{sup 4}/c{sup 3})(1 + sin{sup 2}{alpha}) for a star with the dipole moment {mu}, rotation frequency {Omega}{sub *}, and magnetic inclination angle {alpha}. We also discuss the effects of current sheet resistivity and reconnection on the structure and evolution of the magnetosphere.
Author: Anatoly Spitkovsky
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
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Book Description
Pulsar spindown forms a reliable yet enigmatic prototype for the energy loss processes in many astrophysical objects including accretion disks and back holes. In this paper we review the physics of pulsar magnetospheres, concentrating on recent developments in force-free modeling of the magnetospheric structure. In particular, we discuss a new method for solving the equations of time-dependent force-free relativistic MHD in application to pulsars. This method allows to dynamically study the formation of the magnetosphere and its response to perturbations, opening a qualitatively new window on pulsar phenomena. Applications of the method to other magnetized rotators, such as magnetars and accretion disks, are also discussed.
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: V. S. Beskin
Publisher: Cambridge University Press
ISBN: 0521417465
Category : Science
Languages : en
Pages : 434
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Book Description
This book presents the theory of the electrodynamic phenomena that occur in the magnetosphere of a pulsar. It also provides a clear picture of the formation and evolution of neutron stars. The authors address the basic physical processes of electron-positron plasma production, the generation of electric fields and currents, and the emission of radio waves and gamma rays. The book also reviews the current observational data, and devotes a complete chapter to a detailed comparison of this data with accepted theory and with some recent theoretical predictions. Tables containing the values of the physical parameters of all observed radio pulsars are also provided.
Author: David Carreto Fidalgo
Publisher: Springer
ISBN: 3030241947
Category : Science
Languages : en
Pages : 208
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Book Description
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.
Author: Vasily S. Beskin
Publisher: Springer Science & Business Media
ISBN: 3642012906
Category : Science
Languages : en
Pages : 425
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Book Description
Accretion flows, winds and jets of compact astrophysical objects and stars are generally described within the framework of hydrodynamical and magnetohydrodynamical (MHD) flows. Analytical analysis of the problem provides profound physical insights, which are essential for interpreting and understanding the results of numerical simulations. Providing such a physical understanding of MHD Flows in Compact Astrophysical Objects is the main goal of this book, which is an updated translation of a successful Russian graduate textbook. The book provides the first detailed introduction into the method of the Grad-Shafranov equation, describing analytically the very broad class of hydrodynamical and MHD flows. It starts with the classical examples of hydrodynamical accretion onto relativistic and nonrelativistic objects. The force-free limit of the Grad-Shafranov equation allows us to analyze in detail the physics of the magnetospheres of radio pulsars and black holes, including the Blandford-Znajek process of energy extraction from a rotating black hole immersed in an external magnetic field. Finally, on the basis of the full MHD version of the Grad-Shafranov equation the author discusses the problems of jet collimation and particle acceleration in Active Galactic Nuclei, radio pulsars, and Young Stellar Objects. The comparison of the analytical results with numerical simulations demonstrates their good agreement. Assuming that the reader is familiar with the basic physical and mathematical concepts of General Relativity, the author uses the 3+1 split approach which allows the formulation of all results in terms of physically clear language of three dimensional vectors. The book contains detailed derivations of equations, numerous exercises, and an extensive bibliography. It therefore serves as both an introductory text for graduate students and a valuable reference work for researchers in the field.
Author: Nanda Rea
Publisher: Springer Science & Business Media
ISBN: 3642172512
Category : Science
Languages : en
Pages : 656
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Book Description
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.
Author: Giulia Stratta
Publisher: MDPI
ISBN: 3039215884
Category : Science
Languages : en
Pages : 86
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Book Description
The book starts with a review of the established facts on the numerical simulations of binary neutron star mergers and simulations of short GRB jets that highlights the issues that need to be revised and further clarified, as the need to understand how the relativistic outflow was launched, what the initial structure of the outflow is, and how it evolved through its interaction with the binary ejecta. Constraints on a local population of faint short duration GRBs are then provided in light of the GW170817/GRB 170817A event at d~40 Mpc by considering statistical limits on a d < 200 Mpc population. Using past and current GRB detectors, results suggest that GRB 170817A-like events are likely to be rare in existing short GRB catalogues and, if binary neutron star merger rates are at the high end of current estimates, then at most a few percent will be accompanied by detectable gamma-ray flashes in the forthcoming LIGO/Virgo science runs. Indirect information on the nature of short GRBs can be obtained from their host galaxy. The host galaxies of most short GRBs are found to be star-forming, but an important fraction, ∼1/5, are elliptical with negligible star formation. Short bursts often occur at very large off-sets from their hosts, in regions where there is little or no underlying host light. These results provide evidence of progenitors associated with merger of compact object binaries with kick velocities of a few tens of km/s and merger times of ∼1 Gyr. The last two issues of the book tackle the physics of the short GRB radiative processes. Interestingly, it was already noted in the past that the prompt emission for short GRBs and the initial 2 s of long-duration GRBs show similarity in the low energy photon index. This result has been further confirmed using a larger sample of Fermi Gamma-ray burst monitor data. In particular, it has been found that for 25% of GRBs, the photon index is shallower than −2/3, challenging the standard synchrotron emission scenario. The extent up to which the reverse shock component is detectable for short GRBs in radio wavelengths is analyzed. Results show that early, radio bright reverse shock is expected in many cases, but more rapid follow-up observational campaigns are required in order to test these predictions.
Author: Andrew Lyne
Publisher: Cambridge University Press
ISBN: 1108864104
Category : Science
Languages : en
Pages : 422
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Book Description
After more than half a century since their unexpected discovery and identification as neutron stars, the observation and understanding of pulsars touches upon many areas of astronomy and astrophysics. The literature on pulsars is vast and the observational techniques used now cover the whole of the electromagnetic spectrum from radio to gamma-rays. Now in its fifth edition, this volume has been reorganised and features new material throughout. It provides an introduction in historical and physical terms to the many aspects of neutron stars, including condensed matter, physics of the magnetosphere, supernovae and the development of the pulsar population, propagation in the interstellar medium, binary stars, gravitation and general relativity. The current development of a new generation of powerful radio telescopes, designed with pulsar research in mind, makes this survey and guide essential reading for a growing body of students and astronomers.
Author: Abdujappar Rusul
Publisher: Scientific Research Publishing, Inc. USA
ISBN: 1649977247
Category : Antiques & Collectibles
Languages : en
Pages : 237
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Book Description
This monograph is based on my research work in pulsar astronomy, in which Chapters 3, 4, 6, 8, and 9 are mainly based on the previous works that need to be interpreted more deeply with the current progress in the relevant areas of the subjects. I hope this work will provide more insights about the state-switching of intermittent pulsars and the corresponding change in the pulsar magnetosphere. The link to the original paper is given under each chapter for convenience. I believe this monograph may have many defects and shortcomings. Any comments or suggestions are highly appreciated.
