Crab pulsar giant pulses
University of Toronto – Supervisor: Prof. Marten van Kerkwijk
(September 2025 - present)
Neutron stars are some of the most extreme laboratories the universe offers in the study of physics. Their incredible density and magnetic fields offer environments that are inaccessible anywhere else. A subset of neutron stars – known as pulsars – emit radiation from their poles due to particularly strong magnetic fields accelerating charged particles. This emission is received on Earth in the form of brief pulses due to the pulsars rotation in the same way a lighthouse appears to pulse to a distant observer. However, certain pulsars have been found to produce a mysterious additional form of radiation in the called giant pulses (GPs). These GPs are non-periodic but regular pulses whose emission ranges from long wavelength radio to high energy x-rays and demonstrate structure in their emission down to at least the nanosecond timescale; this fast components have been dubbed nanoshots.
Recent studies of giant pulses point to an emission mechanism in which a blob of plasma – or plasmoid – is ejected at relativistic velocities towards the observer. As it travels, the plasmoids are thought to produce nanoshots which form the broader GP. However, this mechanism has not been thoroughly confirmed. Thus my work uses high frequency radio observations (11.5 - 16 GHz) from the Green Bank Telescope in an effort to confirm the proposed emission mechanism. By using higher frequency radio data, we are able to better resolve the nanoshot structure which enables analysis that is not feasible at lower frequencies.
As the sole researcher under my supervisor, I have been responsible for identifying the ~12 000 GPs in over 60 Tb of data. I am currently analyzing how the spectra of consecutive nanoshots vary to extract information about their production and the media through which they passed. Additionally, I am currently exploring methods of undoing the channelization of the data through inverting the polyphase filterbank. This will allow us to achieve increased time resolution to better resolve the nanosecond structure of these pulses.
