Studies of the time-variable sky at various wavelengths have revealed a vast range of unexpected phenomena, some of which have had enormous scientific impact, such as radio pulsars and gamma-ray bursters. At radio wavelengths, large-scale and sensitive examinations have been lacking, and large regions of discovery space remain unexplored. This project will detect and characterize transient and variable sources in the archival record of the Very Large Array (VLA), a large existing resource spanning 30 years, obtained with the most sensitive interferometric telescope in operation today. The algorithms, software pipelines, and expertise developed in the process will be applied to new observations with the Expanded Very Large Array (EVLA), and they will provide an algorithmic portal to the next generation of wide-field, high sensitivity surveys with new telescopes. The university collaboration will work with the National Radio Astronomy Observatory to (i) develop and deploy automated software pipelines on local copies of the VLA archive, (ii) construct algorithms to detect and classify transient and variable radio sources in the archive, (iii) conduct multi-wavelength follow-up observations of sources of interest, and (iv) develop a statistical description and a deeper understanding of the physical processes underlying the radio transient sky. This study will find many new examples of known classes of transient sources, allowing for quantitative analysis, and is likely to discover as-yet-unknown source classes, thus building to a fuller characterization and deeper physical understanding of the dynamic radio sky. The target population includes at least brown dwarfs, low mass stars, nearby extra-solar Jovian planets, neutron stars, X-ray binaries, micro-quasars, radio supernovae and orphan radio afterglows of hidden gamma-ray bursts.
The next generation of radio telescopes is now under construction or development, promising a quantum leap in sky coverage, sensitivity, and data rates. By developing, testing, and deploying algorithms and software pipelines on archival data, this research is an essential step toward handling those new large surveys, especially since it will test the operation of software pipelines in real-time radio astronomy applications. It will also train graduate students and postdoctoral researchers in this burgeoning field, and involve undergraduate students in hands-on research. Outreach activities with high school students and the general public will show how the 'unchanging' heavens are in fact dynamic, full of upheaval, violence, and mystery.
