“They missed it because they hadn’t expected to find anything like it.” 2023 July 19, NatureRead More
The Southern-Sky MWA Rapid Two-Metre (SMART) pulsar survey is an ongoing project to discover new pulsars (neutron stars) in the southern sky (δ < 30°) using the MWA. This is the only pulsar survey capable of looking for pulsars in the Southern Hemisphere at low frequencies (140-170 MHz), and once complete, it is expected to discover hundreds of new pulsars. Apart from its inherent scientific value, it also serves as a valuable reference for future pulsar searches planned with the low-frequency Square Kilometre Array.
The survey design is unique. Thanks to the MWA’s large field of view (~610 square degrees) and its Voltage Capture System, the whole sky (visible to the MWA) can be observed in just 70 observing sessions. With each session recording data for 80 minutes, the whole data collection phase of the survey will take less than 100 hours of observing time, but will ultimately accrue ~3 PB of data. The survey will have a limiting sensitivity of ~2-3 mJy, effectively 3-5 times deeper than the previous low-frequency southern-sky pulsar survey, completed in the 1990s.
The phenomenal survey speed is offset by the impressively large computational cost of processing all the data. For each observation, thousands of so-called “tied-array beams” must be formed by combining the data recorded at each MWA tile in a particular way, to maximise sensitivity towards each direction within the field of view. Each tied-array beam must then be individually searched for pulsar signals, using algorithms that exploit different properties of pulsar signals (the primary one being that the pulses are generally periodic!) All of this processing will take millions upon millions of hours of supercomputing time, and is expected to take years to complete.
A full description of the survey will be published soon (watch this space!)