Searching for variable sources in the rapid temporal survey.
Doctoral thesis, UCL (University College London).
The Rapid Temporal Survey explores the faint, variable sky. I have led the development of the data reduction and analysis pipeline for this survey and have played a leading role in the observation and analysis of follow-up data. The survey and follow-up work is presented in this thesis. The strategy of the survey is to observe fields close to the Galactic plane at a cadence of ~1 min for around two hours down to a depth of g' = 23 The data presented in this thesis cover 31 square degrees of which 16 are within 10^o of the Galactic plane. This is the first dedicated survey to explore this parameter space and such I have had to develop new techniques when dealing with the data. The photometry was performed using a difference imaging technique and resulted in over 3 × 10^6 light curves. This work primarily deals with periodic variability and with this aim I have developed a method which combines two algorithms (Lomb-Scargle and Analysis of Variance) to produce a sub-set of variable sources which contains a very low number of false positives –around 600 out of 1.2 × 10^5 detected variables. For sources brighter than g' = 21 this technique is able to detect – at a confidence above 90 per cent – variability on time-scales of less than 10 min to tens of minutes in source with semi-amplitudes of less than 0.04 mag. Spectroscopic follow-up observations of a number of these targets have been performed and have resulted in the discovery of many different variables from several different classes. I highlight three populations to study in more detail: short-period, variable A-stars; SX Phe and /delta Scuti stars; and pulsating white dwarfs. Of particular interest are the SX Phe stars which I have found to be as far away as 30 kpc from us. I also provide a detailed examination of two variables sources: one is a dwarf nova which was discovered through quasi-periodic oscillations in quiescence, the other a pulsating white dwarf which appears to have a hot companion. I conclude by looking to the future of the project which will continue with a similar strategy but surveying the Kepler field of view.
|Title:||Searching for variable sources in the rapid temporal survey|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Space and Climate Physics|
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