Download or read book Modelling Pulsar Wind Nebulae written by Diego F. Torres and published by Springer. This book was released on 2017-11-13 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Modelling the Nonthermal Emission of the Pulsar Wind Nebula MSH 15 52 written by Sebastian Meßlinger and published by . This book was released on 2013 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spectral Modelling of H E S S Detected Pulsar Wind Nebulae written by Carlo Van Rensburg and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulsar wind nebulae -- H.E.S.S. -- Gamma rays -- Non-thermal emission mechanisms -- Spectral modelling.

Download or read book Modelling the Inverse Compton Emission from Pulsar Wind Nebulae written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, Cherenkov telescopes like H.E.S.S. have identified PulsarWind Nebulae (PWNe) at energies between 100 GeV and 100 TeV as one of the main source populations emitting gamma-rays at these energies. PWNe consist of electrons and positrons emitted by pulsars which radiatively cool down by undergoing synchrotron radiation and inverse Compton scattering. In the case of inverse Compton scattering, the resulting photons show energies up to hundreds of TeV and are therefore making PWNe visible in the mentioned energy range. The first part of this work is dedicated to a model describing the spectral and spatial distribution of the gamma-ray emission from PWNe. Its application to the PWN created by the Geminga pulsar shows an agreement with measured flux values obtained by the Milagro and EGRET experiments. The modelled spatial extension coincides with Milagro observations. The aim of the second part is to verify previously derived analytical results concerning the spectral evolution of electrons due to inverse Compton scattering with a Monte-Carlo simulation using the exact Klein-Nishina cross section. Analytically expected spectral shapes have been qualitatively reproduced for both a burst-like and a stationary injection scenario assumingmono-energetic or blackbody distributed target photons.

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.

Download or read book Modelling the X ray Emission from the Compact Vela Pulsar Wind Nebula written by Michael Johannes Vorster and published by . This book was released on 2010 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spatially dependent Multi wavelength Modeling of Pulsar Wind Nebulae written by and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulsars -- Pulsar wind nebulae -- Supernova remnants -- Gamma rays -- Non-thermal radiation mechanisms -- Neutron stars -- X-rays -- Multi-wavelength astronomy -- Astroparticle physics -- Numerical methods.

Download or read book RADIO POLARISATION STUDY OF TH written by Yik-Ki Ma and published by Open Dissertation Press. This book was released on 2017-01-26 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Spatially Resolved X ray Analysis and Modeling of the Non thermal Emission of the Pulsar Wind Nebula G0 9 0 1 written by Markus Holler and published by . This book was released on 2010 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modelling the Evolution of Pulsar Wind Nebulae written by Michael Johannes Vorster and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composite supernova remnants -- Morphological evolution -- Hydrodynamic -- Kinematic magnetic field -- Pulsar wind nebulae -- Particle evolution models -- Fokker-Planck transport equation -- Spherically-symmetric -- Axisymmetric -- Diffusion -- Drift -- Energy losses -- Saamgestelde supernova-oorblyfsels -- Morfologiese evolusie -- Hidrodinamiese -- Kinematiese magneetveld pulsarwindnewels -- Deeltjie evolusiemodelle -- Fokker-Planck transport vergelyking -- Sferies-simmetries -- Aksiaal-simmetries -- Diffusie -- Dryf -- Energie verliese.

Download or read book Modelling the Evolution of Pulsar Wind Nebulae written by Michael Johannes Vorster and published by . This book was released on 2014 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book X ray Observations of Pulsar Wind Nebulae written by Benson Guest and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Investigation of Energy dependent Morphology in Pulsar Wind Nebulae written by Steven Brett McArthur and published by . This book was released on 2012 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observations of TeV gamma rays enable investigation of extreme, high-energy astrophysical environments. Of the identied TeV sources within the Galaxy, the largest number are pulsar wind nebulae (PWNe), formed by the shocked wind of relativistic leptons emitted by a pulsar and conned by the surrounding medium, with broadband emission arising from synchrotron and inverse Compton mechanisms. PWNe exhibit a wide range of morphologies as a result of a complex evolution, depending on the properties of the parent pulsar and conning medium. This work describes the discovery of gamma-ray emission from the PWN within the supernova remnant (SNR) CTA 1 by the VERITAS telescope array. By imaging the Cherenkov light from gamma-ray induced atmospheric showers, VERITAS revealed an extended TeV nebula surrounding the pulsar PSR J0007+7303. Comparison of the observed properties with known PWN, along with a one-zone model, suggests a recent interaction with the SNR reverse shock and allows for an estimate of the average nebular magnetic eld strength. No signicant energy-dependent morphology is seen. A multi-zone, cylindrically symmetric model is created to investigate tailed-out PWN morphology, accounting for multiple mechanisms for particle transport and cooling. The model is applied to the CTA 1 data, with a limited search of the parameter space performed to t the observed spectrum and extent. Possible improvements to the model performance are discussed.

Download or read book Pulsar Wind Nebulae at High Energies written by and published by . This book was released on 2014 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Relativistic Magnetohydrodynamical Models of Pulsar Wind Nebulae written by Nicholas Francois Camus and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Particle Populations and High Energy Emission in Pulsar Wind Nebulae written by Albert Adam Van Etten and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Energetic particles streaming out from rapidly spinning neutron stars radiate across the electromagnetic spectrum, creating a pulsar wind nebula (PWN). Many PWNe are spatially resolved in the radio, X-ray, and even gamma-ray wavebands, and thereby provide an excellent laboratory to study not only pulsar winds and dynamics, but also shock processes, magnetic field evolution, and particle transport. Single-zone spectral energy distribution (SED) models have long been used to study the global properties of PWNe, but to fully take advantage of high spatial resolution data one must move beyond these simple models. Supported by multiple X-ray PWN observations, we describe multi-zone time-dependent SED model fitting, with particular emphasis on the spatial variations within nebulae. The SED model constrains the wind velocity profile, magnetic field profile, age and spin-down history of the central pulsar, and the PWN injection spectrum. These constraints are of great value to the study of the gamma-ray pulsar population, and to investigations of particle acceleration and the cosmic ray spectrum. The large size of many PWNe in the very high energy gamma-ray (TeV) regime is indicative of significant particle transport over the pulsar lifetime, and in the case study of HESS J1825-137 we find that rapid diffusion of high energy particles is required to match the multi-wavelength data.

Download or read book Spatially Resolved X ray Spectroscopy and Modeling of the Non thermal Emission of the Pulsar Wind Nebula in G21 5 0 9 written by Philipp Willmann and published by . This book was released on 2012 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: