Quasi-Periodic Microstructures in Pulsar Emission: Automated Detection and Archival Survey

The study of quasi-period microstructures in pulsars offers valuable insights into the underlying emission mechanism. However, identifying these features through manual inspection of the intensity time series, often containing thousands to millions of pulses, is both laborious and time-consuming. To address this challenge, we have developed a Python-based software, Quasi-periodic MIcrostructure Search Tool (QMIST), to automate the search for quasi-periodic microstructures in radio pulsar time-series data. We provide a detailed description of the algorithms used in QMIST, demonstrate its efficacy using data on pulsars known to exhibit microstructures, and discuss potential future improvements. Using QMIST, we have performed a multi-epoch survey of quasi-periodic microstructures in a sample of 27 pulsars, using observations from the Giant Metrewave Radio Telescope and the Green Bank Telescope, as well as the archival data from the Parkes telescope. In addition to recovering previously reported microstructures from several pulsars, we report, for the first time, detection of quasi-periodic microstructures in three pulsars, B1451-68, B1706-16 and B1845-19. We also estimate the typical period of microstructures in another pulsar, B0540+23, that was known to exhibit microstructures earlier but the periodicity was unknown. Using the periodicity measurements from our survey, and earlier such measurements from the literature, we confirm the near linear relationship between the microstructure periodicity and the rotation period of pulsars, and discuss our results in the context of the emission mechanism of microstructures.