ATUC Science Meeting Time Domain Astronomy
Marsfield Lecture Theatre – 24th October 2011
Please find abstracts of the CAASTRO presentations and links to PDF copies below. Click here for the meeting program.
Detection of fast radio transients relies on acquisition of a short duration signal pulse among static background signals and noise. Radio emission is affected by plasma along the line-of-sight to the observer, and in particular by a frequency-dependent time delay of pulse arrival due to dispersion by the interstellar medium. Correction for this dispersive effect is crucial for optimal signal detection, typically achieved by application of a matched filter detector on channelized time-series data. The classical matched filter, where the signal is known a priori, is used as the theoretical basis upon which fast transients detection experiments are designed. However, the matched filter is generally unachievable in practise, due to the lack of signal knowledge and computational constraints on real-time detection. I explore the performance of realistic detectors that are applied in real fast transients experiments, as well as a novel detector being explored for the CRAFT fast transients project for ASKAP.
Exploration of the transient Universe is a frontier research area within radio astronomy, and upcoming next-generation facilities will provide exciting avenues to explore this relatively uncharted territory. Searching for fast transients with such instruments however poses a number of challenges in terms of the signal processing and data management requirements as well as the planning of optimal survey strategies. With its moderate number of elements, high sensitivity and flexible design features, the GMRT makes a powerful test-bed for developing and demonstrating novel transient detection methodologies that will be applicable to next generation array instruments. I will describe ongoing efforts aimed at the development of a real-time transient detection pipeline for the GMRT and the pilot transient surveys undertaken. Such developments will provide valuable inputs as next-generation arrays such as ASKAP are designed and commissioned.
Gamma ray bursts are the most powerful explosions in the universe. The properties of these explosions within seconds of the gamma-ray trigger are not well constrained at radio wavelengths. I present results of an automated, high-time resolution follow-up survey for prompt radio emission from GRBs at 1.4 GHz. Using the Parkes 12 m telescope with a single-pixel feed, we observed 9 GRBs, and were on source typically within 2 minutes. We detected two single pulse candidates in the high time resolution data. I will discuss the potential to expand this experiment with future instruments.
CU Virginis is a magnetic Ap star with the unique property of emitting two 100% circularly polarised radio pulses every rotation period. The pulse arrival time of these radio pulses have shown remarkable stability over more than 10 years. In this presentation, I will show our radio observations of CU Virginis with the ATCA and describe how the frequency dependence of the pulse arrival times can give us insight into the geometry of the stellar magnetosphere.