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Author: John A. Lowry Publisher: Nova Publishers ISBN: 9781594545672 Category : Science Languages : en Pages : 228
Book Description
Pulsars are stars, a significant part of whose observed energy output is not continuous but is emitted as distinct flashes or pulses of electromagnetic radiation. Many pulsars also emit some radiation weakly and constantly, forming a background for the more intensive pulses. Three distinct classes of pulsars are presently known to astronomers, according to the source of energy that powers the radiation: Rotation-powered pulsars, where the loss of rotational energy of the star powers the radiation X-ray pulsars, where the gravitational potential energy of accreted matter is the energy source, and Magnetars, where the decay of an extremely strong magnetic field powers the radiation. Although all three classes of objects are neutron stars, their observable behaviour and the underlying physics are quite different. There are, however, connections. For example, X-ray pulsars are probably old rotation-powered pulsars that have already lost most of their energy, and have only become visible again after their binary companions expanded and began transferring matter on to the neutron star. The process of accretion can in turn transfer enough angular momentum to the neutron star to "recycle" it as a rotation-powered millisecond pulsar.
Author: John A. Lowry Publisher: Nova Publishers ISBN: 9781594545672 Category : Science Languages : en Pages : 228
Book Description
Pulsars are stars, a significant part of whose observed energy output is not continuous but is emitted as distinct flashes or pulses of electromagnetic radiation. Many pulsars also emit some radiation weakly and constantly, forming a background for the more intensive pulses. Three distinct classes of pulsars are presently known to astronomers, according to the source of energy that powers the radiation: Rotation-powered pulsars, where the loss of rotational energy of the star powers the radiation X-ray pulsars, where the gravitational potential energy of accreted matter is the energy source, and Magnetars, where the decay of an extremely strong magnetic field powers the radiation. Although all three classes of objects are neutron stars, their observable behaviour and the underlying physics are quite different. There are, however, connections. For example, X-ray pulsars are probably old rotation-powered pulsars that have already lost most of their energy, and have only become visible again after their binary companions expanded and began transferring matter on to the neutron star. The process of accretion can in turn transfer enough angular momentum to the neutron star to "recycle" it as a rotation-powered millisecond pulsar.
Author: Timothy Eugene Edward Olszanski Publisher: ISBN: Category : Neutron stars Languages : en Pages : 232
Book Description
Compact Objects (Neutron Stars) form in the last moments of a star's life, during the violent events known as supernovae. As the star's core fusion falters, matter undergoes a dramatic gravitational compression resulting in internal densities rivaling subatomic particles. Ever since their discovery in the mid-twentieth century, these highly magnetized and rapidly rotating balls of condensed matter have provided a bountiful playground for astronomers seeking out exotic physics. Neutron Stars that emit electromagnetic radiation are seen by observers as Pulsars, named such for the pulse of intensity as the pulsar's radiation beam passes into our line of sight. These beams are comprised of two unique regions with differing phenomenology; core emission that arises close to the pulsar polar cap and centered within the radiation beam, and higher altitude conal emission that lies along the beam's periphery. While pulsars can and do emit over a wide frequency range, most known pulsars are seen as radio sources, at sensitivities where studies of the pulsar single-pulses allows us to probe the rich details of the plasma-filled pulsar magnetosphere. Even then, the radio emission often has a steep spectra, restricting the frequencies in which radio telescopes can study pulsars. We have utilized the unmatched sensitivity of Arecibo Observatory to conduct a multi-frequency single-pulse survey, between 327 MHz and the novel 4.5 GHz, of Arecibo's brightest high-frequency pulsars. The broad frequency range and single-pulse resolutions have allowed us to set accurate beam classifications for these nearly two dozen pulsars while extending constraints on important population trends to higher frequencies. Several of the pulsars in our survey exhibit deviant behavior, and are thus useful as followup case studies to further our understanding of pulsar radio emission. One of the most interesting cases involves pulsar B0823+26, where we find evidence for an age-dependent death-line separating core and conal dominated pulsars, suggesting that the plasma generating capabilities of a pulsar changes as they age. For the other three, they fall in the "Partial Cone"' class; a type of pulsar that is characterized by strong delays in their emission. We find that all three of these pulsars show evidence of core emission.
Author: Pranab Ghosh Publisher: World Scientific ISBN: 9810247443 Category : Science Languages : en Pages : 793
Book Description
This book is an introduction to pulsars, a key area in high energy astrophysics with continuing potential for fundamental discoveries. Throughout the book runs the unifying thread of the evolutionary link between rotation-powered pulsars and accretion-powered pulsars ? a milestone of modern astrophysics. Early textbooks on pulsars dealt almost entirely with rotation-powered ones, while accounts of pulsars in volumes on X-ray binaries focused almost exclusively on accretion-powered ones. This is the first textbook to treat these two kinds of pulsars simultaneously with equal importance, stressing the fact that both are rotating, magnetic neutron stars, operating under different conditions during different parts of their lives. It describes the observational properties of both kinds of pulsars, summarizes our physical understanding of these properties, and pays detailed attention to the physics of superdense matter which neutron stars are composed of, as well as to the superfluidity which is expected to occur in neutron stars. Evolution from rotation-power to accretion-power, and vice versa, are carefully described. The effects of the strong magnetic fields of neutron stars on themselves, their emission properties, and their environments are discussed, as are the origin and evolution of such magnetic fields. Also treated is the superbly accurate verification of Einstein's theory of general relativity through timing studies of binary pulsars, which led to the award of the Nobel Prize to Hulse and Taylor in 1993. On each topic, the book starts with simple, basic physical concepts, and builds up the exposition to the point where the latest and most exciting developments become accessible to the reader.
Author: Andrew Lyne Publisher: Cambridge University Press ISBN: 1108495222 Category : Science Languages : en Pages : 421
Book Description
A comprehensive introduction to pulsars and radio-emitting neutron stars, including observational and theoretical concepts and applications.
Author: Geoff McNamara Publisher: Springer Science & Business Media ISBN: 038776562X Category : Science Languages : en Pages : 192
Book Description
Pulsars are rapidly spinning neutron stars, the collapsed cores of once massive stars that ended their lives as supernova explosions. In this book, Geoff McNamara explores the history, subsequent discovery and contemporary research into pulsar astronomy. The story of pulsars is brought right up to date with the announcement in 2006 of a new breed of pulsar, Rotating Radio Transients (RRATs), which emit short bursts of radio signals separated by long pauses. These may outnumber conventional radio pulsars by a ratio of four to one. Geoff McNamara ends by pointing out that, despite the enormous success of pulsar research in the second half of the twentieth century, the real discoveries are yet to be made including, perhaps, the detection of the hypothetical pulsar black hole binary system by the proposed Square Kilometre Array - the largest single radio telescope in the world.
Author: Rutger van Haasteren Publisher: Springer Science & Business Media ISBN: 3642395996 Category : Science Languages : en Pages : 149
Book Description
Pulsar timing is a promising method for detecting gravitational waves in the nano-Hertz band. In his prize winning Ph.D. thesis Rutger van Haasteren deals with how one takes thousands of seemingly random timing residuals which are measured by pulsar observers, and extracts information about the presence and character of the gravitational waves in the nano-Hertz band that are washing over our Galaxy. The author presents a sophisticated mathematical algorithm that deals with this issue. His algorithm is probably the most well-developed of those that are currently in use in the Pulsar Timing Array community. In chapter 3, the gravitational-wave memory effect is described. This is one of the first descriptions of this interesting effect in relation with pulsar timing, which may become observable in future Pulsar Timing Array projects. The last part of the work is dedicated to an effort to combine the European pulsar timing data sets in order to search for gravitational waves. This study has placed the most stringent limit to date on the intensity of gravitational waves that are produced by pairs of supermassive black holes dancing around each other in distant galaxies, as well as those that may be produced by vibrating cosmic strings. Rutger van Haasteren has won the 2011 GWIC Thesis Prize of the Gravitational Wave International Community for his innovative work in various directions of the search for gravitational waves by pulsar timing. The work is presented in this Ph.D. thesis.
Author: Joeri van Leeuwen Publisher: Cambridge University Press ISBN: 9781107033801 Category : Science Languages : en Pages : 520
Book Description
IAU Symposium 291 features a rich harvest of recent scientific discoveries and looks forward to the many exciting avenues for future neutron-star research. The volume starts with general, lively, comprehensive introductions to three main themes that successfully communicate the excitement of current pulsar research. The subsequent reviews and contributions on hot topics cover: ongoing searches for pulsars, both radio and gamma-ray; neutron star formation and properties; binary pulsars; pulsar timing and tests of gravitational theories; magnetars; radio transients; radio, X-ray and gamma-ray pulse properties and emission mechanisms; and future facilities. This range of topics clearly illustrates the diverse nature and wide application of neutron-star research. Through a combination of introductory reviews and practically complete coverage of current results from across the electromagnetic spectrum, IAU S291 is the perfect reference for neutron-star researchers and also provides an excellent read for advanced undergraduate and starting graduate students.
Author: Diego F. Torres Publisher: Springer ISBN: 3319630318 Category : Science Languages : en Pages : 318
Book Description
In view of the current and forthcoming observational data on pulsar wind nebulae, this book offers an assessment of the theoretical state of the art of modelling them. The expert authors also review the observational status of the field and provide an outlook for future developments. During the last few years, significant progress on the study of pulsar wind nebulae (PWNe) has been attained both from a theoretical and an observational perspective, perhaps focusing on the closest, more energetic, and best studied nebula: the Crab, which appears in the cover. Now, the number of TeV detected PWNe is similar to the number of characterized nebulae observed at other frequencies over decades of observations. And in just a few years, the Cherenkov Telescope Array will increase this number to several hundreds, actually providing an essentially complete account of TeV emitting PWNe in the Galaxy. At the other end of the multi-frequency spectrum, the SKA and its pathfinder instruments, will reveal thousands of new pulsars, and map in exquisite detail the radiation surrounding them for several hundreds of nebulae. By carefully reviewing the state of the art in pulsar nebula research this book prepares scientists and PhD students for future work and progress in the field.
Author: John A. Lowry
Author: John A. Lowry
Author: D. R. Lorimer
Author: Timothy Eugene Edward Olszanski
Author: Pranab Ghosh
Author: Andrew Lyne
Author: Geoff McNamara
Author: Andrew Lyne
Author: Rutger van Haasteren
Author: Joeri van Leeuwen
Author: Diego F. Torres