Abstract

Contributed Talk - Splinter GalaxyEvol

Thursday, 12 September 2024, 14:30   (S21)

The Coherence Length of Galactic Magnetic Fields: Implications for Observations

Leonard Kaiser, Daniel Seifried, Tim-Eric Rathjen
I. Physics Institute, University of Cologne

Magnetic fields in the interstellar medium are closely tied to the matter distribution and possess an energy density comparable to turbulent gas motions, making them dynamically significant. Thus, a complete picture of star formation requires accurate observations of galactic magnetic fields. In this work, we analyse magnetic field properties using magnetohydrodynamic simulations of the interstellar medium in disk galaxies that are part of the SILCC project. The simulations cover environments ranging from our quiescent local galactic neighbourhood to violent starburst galaxies. Specifically, we investigate up to which spatial scales the magnetic field remains correlated with itself, allowing for coherent observations. To this end, we calculate the autocorrelation of the field and consider the typical length of domains where the field direction remains unchanged. Both methods hint at a correlation length of ~ 100 pc. Additionally, we examine the time evolution of this correlation length in relation to relevant quantities, such as the star formation rate, to understand its origin. The spatial coherence has an impact on magnetic field observations. To further investigate this, we present correlations between rotation measure, average magnetic field strength, and electron column density. We show how well the galactic magnetic field can be reconstructed from observations of Faraday rotation. This will aid in interpreting existing data and guiding future observations.