A comparison of multi-phase magnetic field tracers in a high-galactic latitude region of the filamentary interstellar medium

Abstract

Understanding how the Galactic magnetic field threads the multiphase interstellar medium (ISM) remains a considerable challenge, as different magnetic field tracers probe dissimilar phases and field components. We search for evidence of a common magnetic field shared between the ionized and neutral ISM by comparing 1.4 GHz radio continuum polarization and H I line emission from the Galactic Arecibo L-Band Feed Array Continuum Transit Survey (GALFACTS) and Galactic Arecibo L-Band Feed Array H I (GALFA-H I) survey, respectively. We compute the polarization gradient of the continuum emission and search for associations with diffuse/translucent H I structures. The polarization gradient is sensitive to changes in the integrated product of the thermal electron density and line-of-sight field strength (B∥) in warm ionized gas, while narrow H I structures highlight the plane-ofsky field orientation in cold neutral gas. We identified one region in the high Galactic latitude Arecibo sky, G216 +26 centered on (ℓ, b) ∼ (216°, +26°), containing filaments in the polarization gradient that are aligned with narrow H I structures roughly parallel to the Galactic plane.