High cadence pulsar timing with CHIME/Pulsar

Pulsars are rapidly rotating, highly magnetized neutron stars—the collapsed remnants of massive stars following a supernova explosion. They produce beams of radiation that reach our observatories on Earth at regular intervals. The precise timing of these radio pulses has many applications, including exploring fundamental physics, testing the predictions of general relativity, probing the interstellar medium, and even detecting gravitational waves. This work investigates variability in pulsar emission using the unprecedented observing cadence of the CHIME telescope. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a radio telescope near Penticton, British Columbia, Canada. Although initially conceived as a cosmology experiment, it has proven to be an excellent instrument for discovering and studying radio transients. This thesis utilizes the CHIME/Pulsar science backend. First, for PSR B0540+23 we conduct an analysis to explore emission modulation during periods of low solar elongation, which occur once a year. Each year, the pulsar is occulted by the solar wind due to its position in the sky. We observe dispersion measure variations caused by excess solar wind electrons along the line of sight and infer a solar electron density based on these observations. Next, we study nulling and mode-changing behavior in PSRs B0809+74 and B0329+54. We employ a matched filtering pipeline to identify this behavior. We investigate links between these phenomena and an excess of outlier TOAs identified by the NANOGrav Collaboration’s outlier analysis. We find that the outlier analysis is sensitive to mode-changing in PSR B0329+54. These findings highlight the utility of CHIME/Pulsar’s daily observing cadence for studying pulsar emission. With the capabilities of CHIME/Pulsar, we are able to identify yearly occultations of PSR B0540+23 by the solar wind. We also provide a foundation for applying the NANOGrav outlier analysis to identify mode-changing in pulsars. The results of this work highlight the value of CHIME/Pulsar in studying a wide range of pulsar emission phenomena.