New methods and the discovery of diverse phenomena at low frequencies with AARTFAAC
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| Award date | 25-06-2020 |
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| Number of pages | 138 |
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| Abstract |
This thesis focuses on the commissioning of the Amsterdam ASTRON Radio Transient Facility And Analysis Centre (AARTFAAC) all sky monitor, and the results of our survey for brief, bright, low frequency, radio transients.
We initially used 32 hours, covering the Northern Hemisphere, to observe sources across the sky, simultaneously, for hours while sampling with one second resolution. This enabled accurate inference of the 60 MHz flux density for 167 bright sources. Next, we analysed 545 hours spanning three years for the AARTFAAC transient survey. The primary goals of the survey were to develop techniques for automated detection of transient candidates. This involved creating algorithms to efficiently filter hundreds of thousands spurious candidates, leaving a reasonable number for manual follow-up. We discovered two classes of low frequency transients within the survey. The first were giant-pulses from PSR B0850+08. With fluences up to 177 Jy s at 60 MHz, these are the most energetic pulses from this source, below 100 MHz. With over 100 hours of observations we performed a long term study of the giant-pulse activity rate and fluence distributions. Next, we report on a population of apparent transient sources resulting from intermittent conditions in the near earth plasma environment. The turbulent structure produces plasma lenses magnifying the flux density of background objects to 100x tens of seconds. Within this noisy background, we detected a candidate, potentially of extragalactic origin. Through the survey we constrain the rate of unknown populations of brief, bright, transients at less than 1.1 all-sky per day. |
| Document type | PhD thesis |
| Language | English |
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