Amit Seta (ANU)

Abstract: Magnetic fields and turbulence are important components of the interstellar medium (ISM) of star-forming galaxies. It is challenging to measure the properties of the small-scale ISM magnetic fields (magnetic fields at scales smaller than the turbulence driving scale). Using numerical simulations, we demonstrate how the second-order rotation measure (RM, which depends on thermal electron density and magnetic field) structure function can probe the properties of small-scale random magnetic fields. Particularly, we show that computing the RM structure function with a higher-order stencil (more than the commonly-used two-point stencil) is necessary to accurately estimate the slope of the structure function. We then apply our results to radio polarisation observations of the Small and Large Magellanic Clouds and determine the strength and scale of their small-scale magnetic fields.