Pulsars are laboratories for extreme physics unachievable on Earth. As individual sources and possible orbital companions can be used to study magnetospheric, emission, and superfluid physics, general relativistic effects, and stellar and binary evolution. As populations they exhibit a wide range of sub-types, with parameters varying by many orders of magnitude signifying fundamental differences in their evolutionary history and potential uses. There are currently around 2200 known pulsars in the Milky Way, the Magellanic clouds, and globular clusters, most of which have been discovered with radio survey observations. These observations, as well as being suitable for detecting the repeating signals from pulsars, are well suited for identifying other transient astronomical radio bursts that last just a few milliseconds that either singular in nature, or rarely repeating. Prior to the work of this thesis non-repeating radio transients at extragalactic distances had possibly been discovered, however with just one example status a real astronomical sources was in doubt. Finding more of these sources was a vital to proving they were real and to open up the universe for millisecond-duration radio astronomy. The High Time Resolution Universe survey uses the multibeam receiver on the 64-m Parkes radio telescope to search the whole visible sky for pulsars and transients. The temporal and spectral resolution of the receiver and the digital back-end enable the detection of relatively faint, and distant radio sources. From the Parkes telescope a large portion of the Galactic plane can be seen, a rich hunting ground for radio pulsars of all types, while previously poorly surveyed regions away from the Galactic plane are also covered. I have made a number of pulsar discoveries in the survey, including some rare systems. These include PSR J1226-6208, a possible double neutron star system in a remarkably circular orbit, PSR J1431-471 which is being eclipsed by its companion with each orbit, PSR J1729-2117 which is an unusual isolated recycled pulsar, and PSR J2322-2650 which has a companion of very low mass - just 7 x 10⁻⁴M_⊙, amongst others. I begin this thesis with the study of these pulsars and discuss their histories. In addition, I demonstrate that optical observations of the companions to some of the newly discovered pulsars in the High Time Resolution Universe survey may result in a measurement of their age and that of the pulsar. I have discovered five new extragalactic single radio bursts, confirming them as an astronomical population. These appear to occur frequently, with a rate of 1.0^+0.6_-0.5 x 10⁴ sky⁻¹ day⁻¹. The sources are likely at cosmological distances - with redshifts between 0.45 and 1.45, making them more than half way to the Big Bang in the most distant case. This implies their luminosities must be enormous, 10³¹ to 10³³ J emitted in just a few milliseconds. Their source is unknown but I present an analysis of the options. I also perform a population simulation of the bursts which demonstrates how their intrinsic spectrum could be measured, even for unlocalised FRBs: early indications are that the spectral index of FRBs < 0.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23703号 / 理博第4793号 / 新制||理||1686(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 井岡 邦仁, 教授 萩野 浩一, 教授 田中 貴浩 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

As new radio telescopes and processing facilities are being built, the amount of data that has to be processed is growing continuously. This poses significant challenges, especially if the real-time processing is required, which is important for surveys looking for poorly understood objects, such as Fast Radio Bursts, where quick detection and localisation can enable rapid follow-up observations at different frequencies. With the data rates increasing all the time, new processing techniques using the newest hardware, such as GPUs, have to be developed. A new pipeline, called PAFINDER, has been developed to process data taken with a phased array feed, which can generate up to 36 beams on the sky, with data rates of 25 GBps per beam. With the majority of work done on GPUs, the pipeline reaches real-time performance when generating filterbank files used for offline processing. The full real-time processing, including single-pulse searches has also been implemented and has been shown to perform well under favourable conditions. The pipeline was successfully used to record and process data containing observations of RRAT J1819-1458 and positions on the sky where 3 FRBs have been observed previously, including the repeating FRB121102. Detailed examination of J1819-1458 single-pulse detections revealed a complex emission environment with pulses coming from three different rotation phase bands and a number of multi-component emissions. No new FRBs and no repeated bursts from FRB121102 have been detected. The GMRT High Resolution Southern Sky survey observes the sky at high galactic latitudes, searching for new pulsars and FRBs. 127 hours of data have been searched for the presence of any new bursts, with the help of new pipeline developed for this survey. No new FRBs have been found, which can be the result of bad RFI pollution, which was not fully removed despite new techniques being developed and combined with the existing solutions to mitigate these negative effects. Using the best estimates on the total amount of data that has been processed correctly, obtained using new single-pulse simulation software, no detections were found to be consistent with the expected rates for standard candle FRBs with a flat or positive spectrum.

This diploma paper is focused on developing the quality manual ISO 9000 and 14000. It is created for a particular workplace protection of the population, but also in a way that it can be applied to any departing unit of the Fire and Rescue Service. Herein it is processed a management system built for the platoon of central fire station in accordance with standard ČSN EN ISO 9001.

京都大学 / 0048 / 新制・論文博士 / 博士(経済学) / 乙第13082号 / 論経博第395号 / 新制||経||281(附属図書館) / 京都大学大学院経済学研究科経済政策学専攻 / (主査)教授 岩本 武和, 教授 澤邉 紀生, 教授 島本 哲朗 / 学位規則第4条第2項該当 / Doctor of Economics / Kyoto University / DGAM

<p>     </p> <p>This article-based dissertation provides a review of the broad subject of Neutron Star- their emission properties, plasmoids ejection events, and their proposed physical mechanisms. The primary purpose of this dissertation is to provide an extensive description of the research projects I undertook during my tenure as a Graduate Research Assistant, under the guidance of my advisor Prof. Maxim Lyutikov. </p> <p><br></p> <p>Chapter 1 provides a broad overview of the Neutron stars, their classification, proposed emission models, and a summary of magnetars and associated observed phenomena. </p> <p><br></p> <p>In Chapter 2, I present a version of the research article published in the <em>Monthly Notices of the Royal Astronomical Society</em>. The work is titled "Rotating Neutron Stars Without Light Cylinders" and discusses twisted and differentially rotating neutron star magnetospheres that do not have a light cylinder, generate no wind, and thus do not spin down. The magnetosphere of such neutron stars is composed of embedded differentially rotating flux surfaces, with the angular velocity decreasing as Ω ∼ 1/r. It was found, both analytically and using numerical simulations, that for spin parameters larger than some critical value, the light cylinder appears, the magnetosphere opens up, and the wind is generated. </p> <p>In Chapter 3, I present a version of the research article published in <em>The Astrophysical Journal</em>. The work is titled "Relativistic Magnetic Explosions" and was undertaken under the supervision of Dr. Maxim Barkov, in collaboration with Dr. Konstantinos N. Gourgou- liatos and Dr. Lyutikov2 Barkov. It discusses the dynamics of magnetically driven explosive astrophysical events, like magnetar bursts and flares. We model a relativistic expansion of highly magnetized and highly magnetically over-pressurized clouds. We observe that the corresponding dynamics are qualitatively different from fluid explosions due to the topological constraint of the conservation of the magnetic flux. Using analytical, relativistic MHD as well as force-free calculations, we find that the creation of a relativistically expanding, causally disconnected flow obeys a threshold condition: it requires sufficiently high initial over-pressure and sufficiently quick decrease of the pressure in the external medium (the pre-explosion wind). In the subcritical case, the magnetic cloud just puffs up" and quietly expands with the pre-flare wind. We also find a compact analytical solution to the Prendergast problem - the expansion of force-free plasma into the vacuum. </p> <p><br></p> <p>Chapter 4 is the extension of the work in Chapter 3 and focuses on the dynamics of relativistic Coronal Mass Ejections (CMEs), from launching by shearing of foot-points (either slowly or suddenly), to propagation in the preceding magnetar wind. The work has been accepted to be published in <em>Monthly Notices of the Royal Astronomical Society</em>. For slow shear, we find that most of the energy injected into the CME is first spent on the work done on breaking through the over-laying magnetic field. At later stages, sufficiently powerful CMEs may lead to the detonation of a CME and opening of the magnetosphere beyond some equipartition radius req, where the decreasing energy of the CME becomes larger than the decreasing external magnetospheric energy. Post-CME magnetosphere relaxes via the formation of a plasmoid-mediated current sheet, initially at req, and slowly reaching the light cylinder. Both the location of the foot-point shear and the global magnetospheric configuration affect the frequent/weak versus rare/powerful CME dichotomy - to produce powerful flares the slow shear should be limited to field lines that close in near the star.  After the creation of a topologically disconnected flux tube, the tube quickly (at ∼ the light cylinder) comes into force-balance with the preceding wind and is passively advected/frozen in the wind afterward. </p> <p>For fast shear case, the shearing of foot-points leads to the generation of Alfvén wave and the pressure of such Alfvén leads to the opening of the magnetosphere. At distances much larger than the light cylinder, the resulting shear Alfvén waves propagate through the wind non-dissipatively. </p> <p><br></p> <p>In Chapter 5, I switch gears and study the optical polarization of Crab pulsar. I start by deriving a general relation for the polarization direction of the electric dipole-type radiation produced by a particle moving in an arbitrary electromagnetic field. The derived relations are then applied to reproduce optical polarization swings in Crab pulsar assuming a Michel- Bogovalov solution for the current sheet. With this, I was able to reproduce down to intricate details the spin-phase trajectory of the position angle (PA) in the Stokes parameters U-Q plane. This chapter however remains a work in progress. We still don't fully understand the physical mechanism behind the polarization characteristics of the Crab, especially the origin of the point where the inner loop connects with the bigger outer loop. I plan to fully answer these questions before sending our findings for publication. </p> <p><br></p> <p>Chapter 6 summarizes the main results and conclusions of the research projects and mentions the prospects. References are compiled after the appendices so that they are first cited, followed by a CV and a list of publications. </p>

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