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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.
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.
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.
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.
Universe. When it comes to staying current with latest discoveries, clearing away common misconceptions, and harnessing the power of media in the service of students and instructors, no other full-length introduction to astronomy can match it. Now the textbook that has evolved discovery by discovery with the science of astronomy and education technology for over two decades returns in spectacular new edition, thoroughly updated and offering unprecedented media options. Available in Split Volumes Universe: Stars and Galaxies, Fourth Edition, 1-4292-4015-6 Universe: The Solar System, Fourth Edition, 1-4292-4016-4
Unlock the mysteries of the night sky with this comprehensive guide to astronomy. The Practical Astronomer explains and demystifies stargazing and teaches you how to observe and navigate the night sky. Learn how to set up your binoculars and telescopes and find out how to spot different celestial bodies, such as stars, planets, nebulae, and galaxies. Train your telescope into the sky and learn astrophotography with your smartphone camera or digital camera. Hop from one star to another to locate the different constellations or other deep space objects. The book contains sky maps charting all the 88 constellations in both the northern and southern hemisphere, helping you map the star patterns, from Ursa Major and Orion to Pavo and Aquarius. The Practical Astronomer also contains monthly star charts that follow the changing positions of stars in the night sky through the year. Discover the solar system and know about other objects, such as satellites and space stations, that light up the sky. A reference section at the back of the book provides handy information about every planet and includes information about eclipses. Become an accomplished amateur astronomer with this practical guide.
Discover the wonders of the Universe with this complete introduction to observing and understanding the night sky. This practical guide explains and demystifies stargazing, teaching you to recognize different kinds of objects and showing you how they move through the sky over the course of the night and the year. It shows you how to understand and enjoy the cosmos, building your practical astronomy skills from the basics to more advanced techniques. Beginning with an explanation of the Universe itself - how big is it, what shape is it, how old is it, and will it end? - it then takes you on a tour around the night sky, building up your knowledge in simple stages. Practical advice begins with naked-eye observations, then illustrated step-by-step instructions show you how to set up and use binoculars and telescopes and how to take your own pictures of the night sky. It also lets you take a closer look at the different objects you can view in the night sky, telling you how to train your eye to recognize basic patterns of stars (constellations) and how to tell planets apart from other celestial bodies, showing you how to observe them in an innovative step-by-step way. An atlas of the night sky is also included, with charts that can be used in both the northern and southern hemispheres throughout the year. Accessible, inspirational, and authoritative, The Practical Astronomer will enthuse and inform anyone who wants to expand their knowledge of the night sky.
For anyone who's ever looked at the night sky and wanted to know more about the galaxy around them, The Practical Astronomer offers a comprehensive guide to discovering and understanding the mysteries of the solar system and beyond. Illustrated with specially commissioned photography and artwork, and using clear, easy-to-follow text, The Practical Astronomer takes you on a step-by-step journey from the basics of what can be seen with the naked eye from your own backyard, to how you can view more distant objects such as the planets of the solar system, and even galaxies far, far away. The book opens with an explanation of the fundamentals of astronomy, detailing when, where, and how to look at the night sky. It goes on to cover the necessary equipment and clothing that the amateur astronomer needs, reviewing optical equipment such as binoculars and telescopes, how they work and how to use them. A special section focuses on photography and covers the "how-to's" of capturing beautiful images of what you see. The Practical Astronomer aims to foster an awareness and understanding of what you're looking at-be it a planet, star, or asteroid. Different sections are devoted to looking at how the night sky changes, whether that's because it's viewed from a different place in the world or at a different time of year. Star charts and detailed maps of the night sky are included to aid budding astronomers in their quest to know more about this fascinating subject.
Discover the wonders of the Universe with this complete introduction to observing and understanding the night sky. This practical guide explains and demystifies stargazing, teaching you to recognize different kinds of objects and showing you how they move through the sky over the course of the night and the year. It shows you how to understand and enjoy the cosmos, building your practical astronomy skills from the basics to more advanced techniques. Beginning with an explanation of the Universe itself - how big is it, what shape is it, how old is it, and will it end? - it then takes you on a tour around the night sky, building up your knowledge in simple stages. Practical advice begins with naked-eye observations, then illustrated step-by-step instructions show you how to set up and use binoculars and telescopes, and how to take your own pictures of the night sky. It also lets you take a closer look at the different objects you can view in the night sky, telling you how to train your eye to recognize basic patterns of stars (constellations) and how to tell planets apart from other celestial bodies, showing you how to observe them in an innovative step-by-step way. An atlas of the night sky is also included, with charts that can be used in both the northern and southern hemispheres throughout the year. Accessible, inspirational, and authoritative, Stargazing for Beginners will enthuse and inform anyone who wants to expand their knowledge of the night sky.
Pulsars energise particles into lighthouse pencil beams and create extended relativistic outflows, pulsar wind nebulae (PWNe). In the very-high-energy (VHE) gamma-ray wave band, these PWNe represent to date the most populous class of Galactic sources. Nevertheless, the details of the energy conversion mechanisms in the vicinity of pulsars are not well understood, nor is it known which pulsars are able to drive PWNe and emit high-energy radiation. Due to its large field of view and unprecedented sensitivity, H.E.S.S. is the first instrument to allow for deep surveys of the Galactic plane in VHE gamma rays. This work presents the first ever systematic investigation of the connection of VHE gamma-ray sources and PWNe. Besides presenting two new candidate PWNe detected in this search, it is shown that pulsars with large spin-down energy flux are indeed with high probability associated with VHE gamma-ray sources, implying the existence of an efficient mechanism by which a large fraction of pulsar spin-down energy is converted into kinetic energy of particles. The results presented here make it very likely that future more sensitive VHE gamma-ray instruments will detect a rapidly increasing number of lower-luminosity PWNe.