Author :
Publisher :
Page : pages
File Size : 41,47 MB
Release : 2015
Category :
ISBN :
I analyze filament G359.97-0.038 by incorporating broad-band morphological and spectral data from radio (5.5 and 8.3 GHz) and X-ray data with NuSTAR data. I conclude that it is not a PWN but more likely the result of an interaction between the Sgr A East remnant and the nearby molecular cloud. Lastly I observe the filament G0.13-0.11, likely a PWN elongated by the ram pressure from the nearby Radio Arc.
Author : David Carreto Fidalgo
Publisher : Springer
Page : 213 pages
File Size : 42,40 MB
Release : 2019-07-17
Category : Science
ISBN : 3030241947
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 : Diego F. Torres
Publisher : Springer
Page : 318 pages
File Size : 35,37 MB
Release : 2017-11-13
Category : Science
ISBN : 3319630318
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 : 項之悦
Publisher :
Page : 0 pages
File Size : 29,92 MB
Release : 2021
Category :
ISBN :
Author : Werner Becker
Publisher : Springer Science & Business Media
Page : 702 pages
File Size : 19,44 MB
Release : 2009-02-11
Category : Science
ISBN : 354076965X
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.
Author : Andrew Lyne
Publisher : Cambridge University Press
Page : 422 pages
File Size : 40,89 MB
Release : 2022-08-04
Category : Science
ISBN : 1108864104
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 : Benson Guest
Publisher :
Page : 0 pages
File Size : 11,37 MB
Release : 2020
Category :
ISBN :
Pulsar wind nebulae (PWNe) are non-thermal bubbles blown by the relativistic winds of rapidly rotating neutron stars. They are formed in the cavity evacuated by the explosion of a core collapse supernova, and depending on their evolutionary stage may appear as a region of hard X-ray emission within a shell of million degree gas, or be the only visible remains of the cataclysmic event. With deep observations and spatially resolved X-ray spectroscopy, we probe the environment surrounding PWNe of different ages to search for the missing emission predicted from shock heated gas. We examine the properties of the relativistic winds and compare our results with diffusion models and hydrodynamic simulations. In the process of creating consistent spectral maps of PWNe we discover variability in archival Chandra data, opening a new window for observations and theory to explore. We present the deepest Chandra study of G21.5-0.9, finding faint thermal emission embedded in the primarily non-thermal limb-brightened shell. In analysing the synchrotron emission from the PWN, we find an adequate fit with a spatially averaged diffusion model to describe the transport of the wind through the nebula. Unlike the limb-brightened shell previously revealed in G21.5-0.9 with sufficient observation time, the missing shell in CTB 87 remains hidden despite a deep XMM-Newton observation. We constrain the ambient density and favour expansion into a low density bubble. We attribute the morphology to an interaction of the wind with a reverse shock due to the motion of the pulsar within a ~20 kyr old remnant. We present the first X-ray spectral map of this remnant, and find a good agreement with a simulated map. While merging or simultaneously fitting observations separated by extended periods of time will improve statistics, it may also hide unknown variability. We discover significant spectral variability in G21.5-0.9, 3C58, and Kes 75, and marginal evidence of variability in G11.2-0.3 and G54.1+0.3 to be confirmed with future observations.
Author : Yik-Ki Ma
Publisher : Open Dissertation Press
Page : 92 pages
File Size : 39,78 MB
Release : 2017-01-26
Category : Science
ISBN : 9781361013892
This dissertation, "Radio Polarisation Study of the Snail Pulsar Wind Nebula in Supernova Remnant G327.1-1.1" by Yik-ki, Ma, 馬奕騏, 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: Pulsar wind nebulae (PWNe) are believed to be acceleration sites of cosmic rays in the Galaxy. In the acceleration process, magnetic field plays an important role. Radio polarisation measurements offer a direct probe of the magnetic field geometry of astronomical objects, but such experiments have rarely been conducted on PWNe, especially for evolved systems. PWNe can be crushed by the supernova reverse shock at an age of 10 kyr. Previous hydrodynamical simulations show that such interactions can result in a turbulent environment in the nebula interior, suggesting a tangled magnetic field. In this thesis, I present a radio study of the Snail PWN in the composite supernova remnant G327.1-1.1 using the Australia Telescope Compact Array. This PWN is believed to have already interacted with the supernova reverse shock. The study reveals a highly ordered magnetic field configuration in the Snail, which can be explained if either the shockwave could not penetrate into the PWN interior to drive the turbulence, or the characteristic turbulence scale is large. A toy model is built to estimate the turbulence scale assuming the latter scenario. It is found that a simulated PWN with a turbulence scale of one-eighth to one-sixth of the nebula radius and a pulsar wind filling factor of 50-75% can match the observation results. This suggests significant mixing between supernova ejecta and pulsar wind material in this system. In addition, the Snail exhibits a subsonic comet-like protrusion extending from the putative neutron star. Cometary PWNe were found to exhibit a variety of magnetic field configurations but the exact reason remains unclear. The polarisation observations of this system revealed a magnetic field parallel to the nebula elongation, similar to what was found in the Mouse (G359.23-0.82) and the handle of the Frying Pan (G315.78-0.23). This adds an important sample to cometary PWNe for future MHD modelling. Subjects: Supernova remnants Pulsars
Author :
Publisher :
Page : 122 pages
File Size : 16,95 MB
Release : 2014
Category :
ISBN :
Pulsar wind nebulae (PWNe) are the most abundant TeV gamma-ray emitters in the Milky Way. The radiative emission of these objects is powered by fast-rotating pulsars, which donate parts of their rotational energy into winds of relativistic particles. This thesis presents an in-depth study of the detected population of PWNe at high energies. To outline general trends regarding their evolutionary behaviour, a time-dependent model is introduced and compared to the available data. In particular, this work presents two exceptional PWNe which protrude from the rest of the population, namely the Crab Nebula and N 157B. Both objects are driven by pulsars with extremely high rotational energy loss rates. Accordingly, they are often referred to as energetic twins. Modelling the non-thermal multi-wavelength emission of N157B gives access to specific properties of this object, like the magnetic field inside the nebula. Comparing the derived parameters to those of the Crab Nebula reveals large intrinsic differences between the two PWNe. Possible origins of these differences are discussed in context of the resembling pulsars. Compared to the TeV gamma-ray regime, the number of detected PWNe is much smaller in the MeV-GeV gamma-ray range. In the latter range, the Crab Nebula stands out by the recent detection of gamma-ray flares. In general, the measured flux enhancements on short time scales of days to weeks were not expected in the theoretical understanding of PWNe. In this thesis, the variability of the Crab Nebula is analysed using data from the Fermi Large Area Telescope (Fermi-LAT). For the presented analysis, a new gamma-ray reconstruction method is used, providing a higher sensitivity and a lower energy threshold compared to previous analyses. The derived gamma-ray light curve of the Crab Nebula is investigated for flares and periodicity. The detected flares are analysed regarding their energy spectra, and their variety and commonalities are discussed. In addition, a dedicated analysis of the flare which occurred in March 2013 is performed. The derived short-term variability time scale is roughly 6h, implying a small region inside the Crab Nebula to be responsible for the enigmatic flares. The most promising theories explaining the origins of the flux eruptions and gamma-ray variability are discussed in detail. In the technical part of this work, a new analysis framework is presented. The introduced software, called gammalib/ctools, is currently being developed for the future CTA observa- tory. The analysis framework is extensively tested using data from the H. E. S. S. experiment. To conduct proper data analysis in the likelihood framework of gammalib/ctools, a model describing the distribution of background events in H.E.S.S. data is presented. The software provides the infrastructure to combine data from several instruments in one analysis. To study the gamma-ray emitting PWN population, data from Fermi-LAT and H. E. S. S. are combined in the likelihood framework of gammalib/ctools. In particular, the spectral peak, which usually lies in the overlap energy regime between these two instruments, is determined with the presented analysis framework. The derived measurements are compared to the predictions from the time-dependent model. The combined analysis supports the conclusion of a diverse population of gamma-ray emitting PWNe.
Author : Sebastian Meßlinger
Publisher :
Page : 34 pages
File Size : 20,88 MB
Release : 2013
Category :
ISBN :
