Marsfield Lecture Theatre

Charlotte Sobey

Charlotte Sobey Colloquium: Untangling magnetic fields using LOFAR observations of pulsars

The focus of this talk is using next-generation low-frequency radio telescopes (e.g. LOFAR: The Low Frequency Array) to observe pulsars, which provide powerful probes of astrophysical plasmas that span many orders of magnitude in magnetic field strength and scale. Firstly, I will focus on the numerous magnetospheric emission characteristics of a mode-changing pulsar, PSR B0823+26, the mechanism behind which is not yet known. This provides further insight into the relationship between these various emission phenomena and what they might teach us about pulsar magnetospheres.

LOFAR's large fractional bandwidth and collecting area combine to produce high-quality polarisation profiles of pulsars below 200 MHz. I will present a growing catalogue of Faraday rotation measures (RMs) towards over 160 pulsars that are among the highest-precision ionosphere-corrected RMs towards pulsars ever achieved. Combining the accurate RMs and dispersion measures from LOFAR pulsar observations provides an efficient method to investigate (and monitor) the 3-D Galactic magnetic field (GMF). The GMF plays a role in many astrophysical processes over many scales. However, its 3-D morphology, particularly in the halo, is not yet well understood. These measurements, along with future efforts, will be valuable for furthering our understanding of the 3-D GMF structure.