Studying the southerly eclipsing millisecond pulsar J1748-2446A using MeerKAT

Lekomola, Senate

Studying the southerly eclipsing millisecond pulsar J1748-2446A using MeerKAT

Thesis / Dissertation

2024

Publisher

University of Cape Town

Department

Department of Astronomy

Faculty

Faculty of Science

Abstract

This study focuses on the changes of the dispersion measure (DM), rotation measure (RM) and scattering characteristics of PSR J1748-2446A, a millisecond pulsar in an ablating binary system, as its pulses pass through the companion star's outflow material. To conduct this analysis we used two observations from the South African MeerKAT telescope at L-band frequencies. As PSR J1748-2446A transitions in and out of an eclipse, our observations of its radio emission noted a maximum dispersion measure (DM) increase of 0.089 pc cm−3 in Observation 1 and of 0.055 pc cm−3 in Observation 2. We record a maximum rotation measure (RM) change of 910±10 rad m−2 in Observation 1 and of 769±10 rad m−2 in Observation 2. We also observe characteristic pulse broadening due to multi-path propagation with an increase in characteristic scattering time (τ) of up to 661.41µs in Observation 1 and of up to 36.17µs in Observation 2. Given these changes in DM and RM we have estimated the magnetic field strength of the companion's material to be 57±4 mG and we have estimated RM values deep into the eclipse to go up to 4100 rad m−2 . These findings inform us that the companion material is an ionised and turbulent magnetised plasma, with electron densities and density variations much higher than the typical interstellar medium. Furthermore, we investigated the effects of strong lensing induced by this material and discovered ten magnified single pulses with a “signal-to-noise"ratio, SNR > 10.

Keywords

Astronomy

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