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تسجيل مستخدم جديدThe host galaxies and progenitors of Fast Radio Bursts localized with the Australian Square Kilometre Array Pathfinder
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The Australian SKA Pathfinder (ASKAP) telescope has started to localize Fast Radio Bursts (FRBs) to arcsecond accuracy from the detection of a single pulse, allowing their host galaxies to be reliably identified. We discuss the global properties of the host galaxies of the first four FRBs localized by ASKAP, which lie in the redshift range $0.11<z<0.48$. All four are massive galaxies (log( $M_{*}/ M_{odot}$) $sim 9.4 -10.4$) with modest star-formation rates of up to $2M_{odot}$yr$^{-1}$ -- very different to the host galaxy of the first repeating FRB 121102, which is a dwarf galaxy with a high specific star-formation rate. The FRBs localized by ASKAP typically lie in the outskirts of their host galaxies, which appears to rule out FRB progenitor models that invoke active galactic nuclei (AGN) or free-floating cosmic strings. The stellar population seen in these host galaxies also disfavors models in which all FRBs arise from young magnetars produced by superluminous supernovae (SLSNe), as proposed for the progenitor of FRB 121102. A range of other progenitor models (including compact-object mergers and magnetars arising from normal core-collapse supernovae) remain plausible.
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[ABRIDGED VERSION] The future of cm and m-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries. The SKA will be 50 times more sensitive than any existing radio facility. A majority o
f the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from 300 MHz to a few GHz. The Australian SKA Pathfinder (ASKAP) is aimed squarely in this frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phase-array feed systems on parabolic reflectors. This large field-of-view makes ASKAP an unprecedented synoptic telescope poised to achieve substantial advances in SKA key science. The central core of ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of the sites selected by the international community as a potential location for the SKA. Following an introductory description of ASKAP, this document contains 7 chapters describing specific science programmes for ASKAP. The combination of location, technological innovation and scientific program will ensure that ASKAP will be a world-leading radio astronomy facility, closely aligned with the scientific and technical direction of the SKA. A brief summary chapter emphasizes the point, and considers discovery space.
One of the Survey Science Projects that the Australian Square Kilometre Array Pathfinder (ASKAP) telescope will do in its first few years of operation is a study of the 21-cm line of HI and the 18-cm lines of OH in the Galactic Plane and the Magellan
ic Clouds and Stream. The wide-field ASKAP can survey a large area with very high sensitivity much faster than a conventional telescope because of its focal plane array of receiver elements. The brightness sensitivity for the widespread spectral line emission of the interstellar medium depends on the beam size and the survey speed. In the GASKAP survey, maps with different resolutions will be synthesized simultaneously; these will be matched to different scientific applications such as diffuse HI and OH emission, OH masers, and HI absorption toward background continuum sources. A great many scientific questions will be answered by the GASKAP survey results; a central topic is the exchange of matter and energy between the Milky Way disk and halo. The survey will show how neutral gas at high altitude (z) above the disk, like the Magellanic Stream, makes its way down through the halo, what changes it experiences along the way, and how much is left behind.
The Australian Square Kilometre Array Pathfinder (ASKAP) presents a number of challenges in the area of source finding and cataloguing. The data rates and image sizes are very large, and require automated processing in a high-performance computing en
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In this paper we describe the system design and capabilities of the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope at the conclusion of its construction project and commencement of science operations. ASKAP is one of the first r
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