The Effect of the Geomagnetic Field on Cosmic Ray Energy Estimates and Large Scale Anisotropy Searches on Data from the Pierre Auger Observatory PDF Download

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Category :
Languages : en
Pages : 20

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We present a comprehensive study of the influence of the geomagnetic field on the energy estimation of extensive air showers with a zenith angle smaller than 60{sup o}, detected at the Pierre Auger Observatory. The geomagnetic field induces an azimuthal modulation of the estimated energy of cosmic rays up to the ≈ 2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the effect of the modulation on large scale anisotropy searches in the arrival direction distributions of cosmic rays. At a given energy, the geomagnetic effect is shown to induce a pseudo-dipolar pattern at the percent level in the declination distribution that needs to be accounted for. In this work, we have identified and quantified a systematic uncertainty affecting the energy determination of cosmic rays detected by the surface detector array of the Pierre Auger Observatory. This systematic uncertainty, induced by the influence of the geomagnetic field on the shower development, has a strength which depends on both the zenith and the azimuthal angles. Consequently, we have shown that it induces distortions of the estimated cosmic ray event rate at a given energy at the percent level in both the azimuthal and the declination distributions, the latter of which mimics an almost dipolar pattern. We have also shown that the induced distortions are already at the level of the statistical uncertainties for a number of events N ≃ 32 000 (we note that the full Auger surface detector array collects about 6500 events per year with energies above 3 EeV). Accounting for these effects is thus essential with regard to the correct interpretation of large scale anisotropy measurements taking explicitly profit from the declination distribution.

Author: J. K. Mandal
Publisher: Springer
ISBN: 8132222504
Category : Technology & Engineering
Languages : en
Pages : 878

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The second international conference on INformation Systems Design and Intelligent Applications (INDIA – 2015) held in Kalyani, India during January 8-9, 2015. The book covers all aspects of information system design, computer science and technology, general sciences, and educational research. Upon a double blind review process, a number of high quality papers are selected and collected in the book, which is composed of two different volumes, and covers a variety of topics, including natural language processing, artificial intelligence, security and privacy, communications, wireless and sensor networks, microelectronics, circuit and systems, machine learning, soft computing, mobile computing and applications, cloud computing, software engineering, graphics and image processing, rural engineering, e-commerce, e-governance, business computing, molecular computing, nano-computing, chemical computing, intelligent computing for GIS and remote sensing, bio-informatics and bio-computing. These fields are not only limited to computer researchers but also include mathematics, chemistry, biology, bio-chemistry, engineering, statistics, and all others in which computer techniques may assist.

Author: Alexander Lazarian
Publisher: Springer
ISBN: 3662446251
Category : Science
Languages : en
Pages : 627

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This volume presents the current knowledge of magnetic fields in diffuse astrophysical media. Starting with an overview of 21st century instrumentation to observe astrophysical magnetic fields, the chapters cover observational techniques, origin of magnetic fields, magnetic turbulence, basic processes in magnetized fluids, the role of magnetic fields for cosmic rays, in the interstellar medium and for star formation. Written by a group of leading experts the book represents an excellent overview of the field. Nonspecialists will find sufficient background to enter the field and be able to appreciate the state of the art.

Author: Michael Stephen Sutherland
Publisher:
ISBN:
Category :
Languages : en
Pages : 182

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Abstract: The Galactic magnetic field is poorly understood. Essentially the only reliable measurements of its properties are the local orientation and field strength. Its behavior at galactic scales is unknown. Historically, magnetic field measurements have been performed using radio astronomy techniques which are sensitive to certain regions of the Galaxy and rely upon models of the distribution of gas and dust within the disk. However, the deflection of trajectories of ultra high energy cosmic rays arriving from extragalactic sources depends only on the properties of the magnetic field. In this work, a method is developed for determining acceptable global models of the Galactic magnetic field by backtracking cosmic rays through the field model. This method constrains the parameter space of magnetic field models by comparing a test statistic between backtracked cosmic rays and isotropic expectations for assumed cosmic ray source and composition hypotheses. Constraints on Galactic magnetic field models are established using data from the southern site of the Pierre Auger Observatory under various source distribution and cosmic ray composition hypotheses. Field models possessing structure similar to the stellar spiral arms are found to be inconsistent with hypotheses of an iron cosmic ray composition and sources selected from catalogs tracing the local matter distribution in the universe. These field models are consistent with hypothesis combinations of proton composition and sources tracing the local matter distribution. In particular, strong constraints are found on the parameter space of bisymmetric magnetic field models scanned under hypotheses of proton composition and sources selected from the 2MRS-VS, Swift 39-month, and VCV catalogs. Assuming that the Galactic magnetic field is well-described by a bisymmetric model under these hypotheses, the magnetic field strength near the Sun is less than 3-4 muG and magnetic pitch angle is less than -8$^{°}$. These results comprise the first measurements of the Galactic magnetic field using ultra-high energy cosmic rays and supplement existing radio astronomical measurements of the Galactic magnetic field.

Author: Claus Grupen
Publisher: Springer Science & Business Media
ISBN: 3642132715
Category : Science
Languages : en
Pages : 1251

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The handbook centers on detection techniques in the field of particle physics, medical imaging and related subjects. It is structured into three parts. The first one is dealing with basic ideas of particle detectors, followed by applications of these devices in high energy physics and other fields. In the last part the large field of medical imaging using similar detection techniques is described. The different chapters of the book are written by world experts in their field. Clear instructions on the detection techniques and principles in terms of relevant operation parameters for scientists and graduate students are given.Detailed tables and diagrams will make this a very useful handbook for the application of these techniques in many different fields like physics, medicine, biology and other areas of natural science.

Author: Todor Stanev
Publisher: Springer Science & Business Media
ISBN: 3540851488
Category : Science
Languages : en
Pages : 334

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Offers an accessible text and reference (a cosmic-ray manual) for graduate students entering the field and high-energy astrophysicists will find this an accessible cosmic-ray manual Easy to read for the general astronomer, the first part describes the standard model of cosmic rays based on our understanding of modern particle physics. Presents the acceleration scenario in some detail in supernovae explosions as well as in the passage of cosmic rays through the Galaxy. Compares experimental data in the atmosphere as well as underground are compared with theoretical models

Author: Erwin O. Flückiger
Publisher:
ISBN:
Category : Cosmic rays
Languages : en
Pages : 40

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Up to now, most studies were carried out assuming azimuthally symmetric currents, neglecting the well established longitudinal asymmetry in the geomagnetic disturbance at low- and mid-latitudes during magnetic storms. The asymmetric perturbations superposed upon a symmetric field depression has been attributed by several authors to a a longitudinally limited, partial ring current with field aligned closure through the auroral ionosphere (Cummings; Fukushima and Kamide; and references therein). It has been the objective of the research covered by this report to study the effects of such magnetospheric current systems on the propagation of cosmic ray particles through the domain of the earth's magnetosphere. The corresponding results were expected to demonstrate the significance of cosmic ray measurements as an additional tool for magnetospheric studies, especially in modeling the disturbed magnetic field in the magnetosphere. In this report, first the approach to the problem is reviewed in Section 2, and examples of the basic tools needed in the procedure are illustrated in Section 3. Then, in Section 4, the results of a simple study correlating local perturbations in the geomagnetic field with cosmic ray cutoff rigidity variations are discussed. Section 5 contains a summary of a detailed quantitative analysis on the effects of a partial ring current and of field-aligned currents on both cutoff rigidities and asymptotic directions in different latitude regions. In conclusions, the significance of the results obtained in the entire study is discussed in Section 6 for both magnetospheric and cosmic ray research.

Author: Gerard Gilmore
Publisher: Springer
ISBN: 9789400756113
Category : Science
Languages : en
Pages : 0

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This is volume 5 of Planets, Stars and Stellar Systems, a six-volume compendium of modern astronomical research, covering subjects of key interest to the main fields of contemporary astronomy. This volume on “Galactic Structure and Stellar Populations”, edited by Gerard F. Gilmore, presents accessible review chapters on Stellar Populations, Chemical Abundances as Population Tracers, Metal-Poor Stars and the Chemical Enrichment of the Universe, The Stellar and Sub-Stellar Initial Mass Function of Simple and Composite Populations, The Galactic Nucleus, The Galactic Bulge, Open Clusters and Their Role in the Galaxy, Star Counts and the Nature of Galactic Thick Disk, The Infrared Galaxy, Interstellar PAHs and Dust, Galactic Neutral Hydrogen, High-Velocity Clouds, Magnetic Fields in Galaxies, Astrophysics of Galactic Charged Cosmic Rays, Gamma-Ray Emission of Supernova Remnants and the Origin of Galactic Cosmic Rays, Galactic Distance Scales, Globular Cluster Dynamical Evolution, Dynamics of Disks and Warps, Mass Distribution and Rotation Curve in the Galaxy, Dark Matter in the Galactic Dwarf Spheroidal Satellites, and History of Dark Matter in Galaxies. All chapters of the handbook were written by practicing professionals. They include sufficient background material and references to the current literature to allow readers to learn enough about a specialty within astronomy, astrophysics and cosmology to get started on their own practical research projects. In the spirit of the series Stars and Stellar Systems published by Chicago University Press in the 1960s and 1970s, each chapter of Planets, Stars and Stellar Systems can stand on its own as a fundamental review of its respective sub-discipline, and each volume can be used as a textbook or recommended reference work for advanced undergraduate or postgraduate courses. Advanced students and professional astronomers in their roles as both lecturers and researchers will welcome Planets, Stars and Stellar Systems as a comprehensive and pedagogical reference work on astronomy, astrophysics and cosmology.

Author: P.K.F. Grieder
Publisher: Elsevier
ISBN: 0080530052
Category : Science
Languages : en
Pages : 1117

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In 1912 Victor Franz Hess made the revolutionary discovery that ionizing radiation is incident upon the Earth from outer space. He showed with ground-based and balloon-borne detectors that the intensity of the radiation did not change significantly between day and night. Consequently, the sun could not be regarded as the sources of this radiation and the question of its origin remained unanswered. Today, almost one hundred years later the question of the origin of the cosmic radiation still remains a mystery.Hess' discovery has given an enormous impetus to large areas of science, in particular to physics, and has played a major role in the formation of our current understanding of universal evolution. For example, the development of new fields of research such as elementary particle physics, modern astrophysics and cosmology are direct consequences of this discovery. Over the years the field of cosmic ray research has evolved in various directions: Firstly, the field of particle physics that was initiated by the discovery of many so-called elementary particles in the cosmic radiation. There is a strong trend from the accelerator physics community to reenter the field of cosmic ray physics, now under the name of astroparticle physics. Secondly, an important branch of cosmic ray physics that has rapidly evolved in conjunction with space exploration concerns the low energy portion of the cosmic ray spectrum. Thirdly, the branch of research that is concerned with the origin, acceleration and propagation of the cosmic radiation represents a great challenge for astrophysics, astronomy and cosmology. Presently very popular fields of research have rapidly evolved, such as high-energy gamma ray and neutrino astronomy. In addition, high-energy neutrino astronomy may soon initiate as a likely spin-off neutrino tomography of the Earth and thus open a unique new branch of geophysical research of the interior of the Earth. Finally, of considerable interest are the biological and medical aspects of the cosmic radiation because of it ionizing character and the inevitable irradiation to which we are exposed. This book is a reference manual for researchers and students of cosmic ray physics and associated fields and phenomena. It is not intended to be a tutorial. However, the book contains an adequate amount of background materials that its content should be useful to a broad community of scientists and professionals. The present book contains chiefly a data collection in compact form that covers the cosmic radiation in the vicinity of the Earth, in the Earth's atmosphere, at sea level and underground. Included are predominantly experimental but also theoretical data. In addition the book contains related data, definitions and important relations. The aim of this book is to offer the reader in a single volume a readily available comprehensive set of data that will save him the need of frequent time consuming literature searches.

Author: Vanessa Maria López Barquero (Ph., D)
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Cosmic rays are detected on Earth with an energy-dependent anisotropy in their arrival direction. Recent experimental results of this arrival distribution of high-energy cosmic rays (CRs) have motivated studies aimed at improving our understanding of the cosmic ray transport and their propagating media. This arrival distribution involves a convolution of the distribution of sources and the effects of the magnetic field properties through which particles propagate. Nonetheless, no comprehensive explanation has been put forth to date. Understanding what causes this cosmic-ray anisotropy and how we can use it to learn about the characteristics of the media they traverse are the central questions of this thesis. More specifically, this dissertation will explore the effects of magnetic fields and various magnetic structures on the anisotropy of arriving CRs from TeV to PeV scales. These contributions can impact the largest angular scale to the medium- and small-scale angular structures. This investigation centers around the effects of three physical processes: one on the chaotic behavior in coherent magnetic structures, another one on magnetic turbulence, and a third on heliospheric effects First, we detail the effects of chaos and trapping in coherent structures on the CR propagation. We apply a new method to characterize chaotic trajectories in bound systems. This method is based on the Finite-Time Lyapunov Exponent (FTLE), which determines the degree of chaos in the particles' trajectories. Furthermore, we model a coherent magnetic structure with time-perturbations that can be used to describe distinct magnetic systems and processes. Our results show that the FTLE, i.e., the level of chaos, is related to the CRs escape time from the system by a power-law relation. Additionally, this power law persists even if perturbations act on the system, pointing to the idea that this specific power law could be an essential parameter of the system. We also find that CRs can be divided into different categories according to their chaotic behavior. Moreover, these categories are distributed in specific regions in the arrival distribution maps. This means that various regions on the map could develop differently from one to another in time. Therefore, this result can provide the basis for time-variability in the CR arrival direction maps. We also discuss how turbulence in the interstellar medium can modify CR trajectories. To investigate this idea, we perform numerical integration of particle trajectories in compressible magnetohydrodynamic turbulence to study how the CRs arrival direction distribution is perturbed when streamed along the local turbulent magnetic field. We found that this inhomogeneous and turbulent interstellar magnetic field can imprint its structure on the CR maps. Another aspect explored is the heliospheric influence on particles with rigidities in the range of 1-10 TV. We test if anisotropies may arise from the interaction with the heliosphere. We employed a magnetic field model of the heliosphere for this goal and performed forward-propagating numerical calculations of particle trajectories. Our results show that the heliosphere can strongly redistribute the particles' directions, making it an indispensable component for the anisotropy. Finally, through these magnetic structures and mechanisms, we can learn about how CRs propagate and their arrival distribution. However, these particles can also act as probes for the properties of the different media they traverse and their places of origin. Therefore, the study of cosmic rays opens multiple doors for a better understanding of the universe.