EMO-GP: Emission Mechanisms of Giant Pulses

Pulsars are spinning neutron stars that emit beams of radio from their magnetic poles. These beams sweep over the Earth and cause the pulsar to appear to be pulsing on and off, like a lighthouse. Since the identification of the first pulsar in 1967, more than three thousand have been discovered. We have found that pulsars are excellent laboratories for fundamental physics, allowing for highly sensitive tests of theories of gravity, searches for the low-frequency gravitational wave background, the properties of nuclear material under enormous pressure, and plasma physics in the presence of extremely strong magnetic fields.

Despite their incredible utility, the basic mechanism by which pulsars produce their emission remains poorly understood in the 55 years since discovery. This puzzle is further complicated by the existence of a rare category of pulsar that emits so-called 'giant pulses'; single pulses many thousands of times brighter than the average which appear to be generated separately to the regular pulsed emission. Recently, there has been the intriguing discovery that patterns in the spectra of giant pulses display striking similarities with another phenomenon, fast radio bursts; bright flashes in radio that can be detected at cosmological distances. Further to this, a fast radio burst originating from our own galaxy has been linked to emission from a radio magnetar (a sub-category of neutron star) and another magnetar has been found to exhibit giant pulse-like emission. These findings hint at the exciting possibility of a common process that links the emission mechanisms of all three phenomena. Therefore, unravelling the mystery of one of these phenomena will potentially lead to important breakthroughs in understanding the others.

In this project, we will thoroughly explore the giant pulse emission phenomenon and its link to fast radio bursts and radio magnetar emission. We will start by using sensitive observations, scheduled to be taken later this year, with the Green Bank Telescope, the Parkes Murriyang Telescope, and the upgraded Giant Metre-Wave Radio Telescope. We will use these observations to carry out a rigorous census of the known giant pulse emitters (including the radio magnetar mentioned above) using ultra-wide-frequency receivers, and to identify new emitters from a list of candidate pulsars. Alongside this, we will establish a giant pulse monitoring programme with the CHIME radio telescope which will take daily observations of the pulsars in this category. The giant pulses data set generated by this programme will be by far the largest ever produced and will allow direct comparisons with data obtained through the CHIME fast radio burst monitoring programme. As an ancillary science goal, we will use the sensitive measurements that are possible with giant pulses to map the local interstellar environment in great detail.

This project will push the field towards a new understanding of these three exotic phenomena and move us a step closer to answering the 55-year-old mystery of how pulsars produce their emission. This will provide valuable insights that will be carried into the upcoming Square Kilometre Array era and enable exciting new initiatives in time domain radio astronomy.