Constraining the Magnetic Field of the Smith High Velocity Cloud using Faraday rotation

Abstract

The Smith Cloud is a high velocity cloud (HVC) with an orbit suggesting it has made at least one passage through the Milky Way disk. A magnetic field found around this cloud has been thought to provide extra stability as it passes through the Galactic halo. We use the Karl G. Jansky Very Large Array to measure Faraday rotation measures (RMs) towards 1105 extragalactic background point sources behind and next to the Smith Cloud to constrain the detailed geometry and strength of its magnetic field. The RM pattern across the cloud gives a detailed morphology of the magnetic field structure which indicates a field draped over the ionized gas and compressed at the head of the cloud. We constrain the peak line-of-sight magnetic field strength to > +5 uG and create a model of the magnetic field to demonstrate that a draped configuration can qualitatively explain the morphology of the observed RMs.

Accepted for publication in ApJ

References in corpus (9)

• Draping of Cluster Magnetic Fields over Bullets and Bubbles -- Morphology and Dynamic Effects
• Distances to Galactic high-velocity clouds. I. Cohen Stream, complex GCP, cloud g1
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• Ionized Gas in the Smith Cloud
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• Physical effects on compact high-velocity clouds in the circumgalactic medium
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• Shattering and growth of cold clouds in galaxy clusters: the role of radiative cooling, magnetic fields and thermal conduction
• A Broadband Spectro-polarimetric View of the NVSS Rotation Measure Catalogue II: Effects of Off-axis Instrumental Polarisation
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• Magnetic fields in star-forming systems (II): examining dust polarization, the Zeeman effect, and the Faraday rotation measure as magnetic field tracers
• Exploring Hydrodynamic Instabilities along the Infalling High-Velocity Cloud Complex A
• The Huge Magnetic Toroids in the Milky Way Halo
• Properties of 3D HI Filaments in the Smith High Velocity Cloud
• A Component of the Smith High Velocity Cloud Now Crossing the Galactic Plane
• Distant probes of RM structure -- Where is the Faraday Rotation towards the Magellanic Leading Arm?
• The Galactic Faraday rotation sky 2020
• Interaction Between Rogue HI Clouds and the Magnetic Field High Above the Galaxy
• Gamma rays from reaccelerated cosmic rays in high velocity clouds colliding with the Galactic disk