Transient Emission Phenomena in Millisecond Pulsars

• Main Author: Mahajan, Nikhil
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2024
• Subjects: Astronomy; Astrophysics; Physics
• ISBN: 9798382192048

Millisecond pulsars are rapidly rotating neutron stars, with rotational periods on the order of milliseconds. The radio emission of millisecond pulsars exhibit a variety of interesting features such as bright transient bursts and rapid state changes which, when better understood, will improve our understanding of the pulsar magnetosphere. In this thesis, I study the transient emission phenomena of two millisecond pulsars. In observations of PSR B1957+20, I present the first ever detection of mode-changing behavior in a millisecond pulsar along with measurements of bright narrow bursts called “giant pulses”. I find that the mode changes affect multiple emission components as well as the giant pulse emission, indicating that mode changing reflects a global reconfiguration of the pulsar’s magnetosphere. Using observations of PSR B1937+21 which also emits giant pulses, I use a novel technique to directly measure the impulse response of the interstellar medium using the bright impulsive giant pulses. This method can be used to probe the structures in the interstellar medium and also to recover the intrinsic emission of the pulsar which was otherwise obscured by scattering and scintillation due to multi-path propagation. I present a detailed study of the intrinsic signals of giant pulses as well as the discovery of “giant micro-pulses” in the emission from PSR B1937+21. Studies of transient emission such as these can be used to place observational constraints on the radio emission mechanism of pulsars as well as improve our ability to use radio pulsars as probes of gravitational waves, the structure of the interstellar medium, and other astrophysical phenomena.