Ben Lorenz, “Pulsar Variability with the ASKAP Variables and Slow Transients Survey”
Mentor: David Kaplan, Physics, Letters & Science (College of)
Poster #67
We present an ongoing analysis of the flux density variability of galactic plane pulsars found within the ASKAP Variables and Slow Transients (VAST) survey. Pulsars are rotating remnants of stars which emit periodic pulses of radio waves. These pulses can change in brightness over time, and little is known about why this happens. This study attempts to provide information which could lead to new insight on the nature of these changes in brightness. The VAST survey is an ongoing survey using wavelengths in the radio sector of the spectrum conducted with the Australian Square Kilometre Array Pathfinder (ASKAP), a radio telescope in Western Australia made up of 36 individual 12-meter dishes. This research was done using observations of pulsars in the Milky Way taken with the ASKAP telescope from 2019 to 2024, and statistical analysis and plotting of results was done using the Nimbus High-Throughput Computing system at the Pawsey Supercomputing Research Centre, a facility also in Western Australia. The statistical analysis in this research involved using a chi-squared test statistic to quantify the variability of each pulsar, coupled with a control chi-squared used to ensure that variability came from the pulsar alone and not errors within the observation. A new control statistic was calculated for each pulsar using sources located near the pulsar but not expected to be variable. We also compared the variability of each pulsar to expected values based on models for refractive interstellar scintillation, a process in which signals vary due to interaction with interstellar gas. Our preliminary findings indicate significant variability in a number of pulsars in the galactic plane, some of which is not well explained by current models.