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The Murchison Widefield Array (MWA) is a joint project between an international consortium of universities to build a low-frequency radio array operating in the frequency range 80–300 MHz. The main scientific goals of the MWA are to detect neutral atomic Hydrogen emission from the cosmological Epoch of Reionization (EoR), to study the sun, the heliosphere, the Earth's ionosphere, and to study radio transient phenomena. The total cost of the project is A$51 million. The MWA is the first so-called large-N array, fully cross-correlating signals from 128 phased tiles, each of which consist of 16 crossed dipoles arranged in a 4x4 square. The field of view is large by the standard of astronomical instruments, being on the order of 30 degrees across. The MWA was to be situated at Mileura Station where initial testing had been conducted then moved southwest to Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO), 800 kilometres north of Perth. This location offers a quiet radio environment and stable climate for observations.〔(The MWA Site in Western Australia ). Murchison Widefield Array. Retrieved on 2 December 2012.〕 The MRO is also the site of CSIRO's Australian Square Kilometre Array Pathfinder〔(Square Kilometre Array ). CSIRO. Retrieved on 2 December 2012.〕 (ASKAP) and one of two candidate sites for the Square Kilometre Array (SKA). In addition to the geographic link, the MWA is a technology and science pathfinder for the SKA. ==Science== The MWA is an inherently versatile instrument with a wide range of potential science goals. Scientific priorities during the early science phase will be determined partly by the evolving instrumental capabilities, and partly by the potential of such studies to accelerate commissioning and the initiation of the key science projects. In astronomy, the highest priority key science project is detection of red-shifted 21 cm signals from HI during the EoR, using power spectral techniques, direct detection of quasar ionised "bubbles", or both. The MWA will be one of the most sensitive EoR instruments yet constructed: its observations should characterise the properties of the sources that are responsible for ionizing the intergalactic medium, chart the evolution of the global neutral fraction, and probe the nature of quasar emissions by constraining the properties of their ionized proximity zones.〔(May 2011). (The Murchison Widefield Array (MWA): Exploring the Epoch of Reionization with the Redshifted 21 cm Line ). Bulletin of the American Astronomical Society, Vol. 43. American Astronomical Society. Retrieved on 2 December 2012.〕 In solar, heliospheric and ionospheric (SHI) research, the highest priority is characterisation of the heliospheric magneto-ionic medium via interplanetary scintillation and Faraday rotation propagation effects using background astronomical radio sources. Secondary key science projects include radio transient detection and monitoring, solar burst imaging, studies of ionospheric phenomena, and a variety of astronomical studies using all-sky survey data. Examples of the latter include Faraday tomography of the interstellar medium, the galactic distribution of cosmic rays, the hidden population of galactic supernova remnants, pulsar emission mechanisms and population statistics, and the low-frequency cosmic web. Most of these secondary projects can be conducted using data collected during or in support of the two highest-priority key science projects, in part because accurate calibration of the MWA requires comprehensive characterisation of the sky across wide instantaneous fields-of-view, as well as accurate characterisation of the behaviour of the ionosphere. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Murchison Widefield Array」の詳細全文を読む スポンサード リンク
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