Magnetized High Velocity Clouds in the Galactic Halo: A New Distance Constraint

Abstract

High velocity gas that does not conform to Galactic rotation is observed throughout the Galaxy's halo. One component of this gas, HI high velocity clouds (HVCs), have attracted attention since their discovery in the 1960s and remain controversial in terms of their origins, largely due to the lack of reliable distance estimates. The recent discovery of enhanced magnetic fields towards HVCs has encouraged us to explore their connection to cloud evolution, kinematics, and survival as they fall through the magnetized Galactic halo. For a reasonable model for the halo magnetic field, most infalling clouds see transverse rather than radial field lines. We find that significant compression (and thereby amplification) of the ambient magnetic field occurs in front of the cloud and in the tail of material stripped from the cloud. The compressed transverse field attenuates hydrodynamical instabilities. This delays cloud destruction, though not indefinitely. The observed B-field compression is related to the cloud's distance from the Galactic plane. As a result, the observed rotation measure provides useful distance information on a cloud's location.

arXiv comment18 pages, 14 figures. Published in ApJ

References in corpus (54)

• PLUTO: a Numerical Code for Computational Astrophysics
• The mass distribution and gravitational potential of the Milky Way
• An eclipsing binary distance to the Large Magellanic Cloud accurate to 2 per cent
• A New Model of the Galactic Magnetic Field
• Gaseous Galaxy Halos
• The PLUTO Code for Adaptive Mesh Computations in Astrophysical Fluid Dynamics
• Magnetic Fields in Spiral Galaxies
• High Velocity Clouds: Building Blocks of the Local Group
• The Galactic Magnetic Field
• Draping of Cluster Magnetic Fields over Bullets and Bubbles -- Morphology and Dynamic Effects
• MHD simulations of the magnetorotational instability in a shearing box with zero net flux. I. The issue of convergence
• Magnetized Gas Clouds can Survive Acceleration by a Hot Wind
• The Launching of Cold Clouds by Galaxy Outflows I: Hydrodynamic Interactions with Radiative Cooling
• On the Continuing Formation of the Andromeda Galaxy: Detection of HI Clouds in the M31 Halo
• Hall magnetohydrodynamics of partially ionized plasmas
• The Escape of Ionizing Photons from the Galaxy
• Starburst-Driven Galactic Winds: Filament Formation and Emission Processes
• H_alpha Emission from High-Velocity Clouds and their Distances
• The survival of gas clouds in the Circumgalactic Medium of Milky Way-like galaxies
• Evolution of clouds in radio galaxy cocoons
• Massive Warm/Hot Galaxy Coronae as Probed by UV/X-ray Oxygen Absorption and Emission: I - Basic Model
• Hydrodynamical Coupling of Mass and Momentum in Multiphase Galactic Winds
• Ram Pressure Stripping of the Large Magellanic Cloud's Disk as a Probe of the Milky Way's Circumgalactic Medium
• The Fate of High-Velocity Clouds: Warm or Cold Cosmic Rain?
• An Accurate Distance to High-Velocity Cloud Complex C
• Highly Ionized Gas Surrounding High Velocity Cloud Complex C
• The Disruption and Fueling of M33
• The Source of Ionization along the Magellanic Stream
• The Launching of Cold Clouds by Galaxy Outflows II: The Role of Thermal Conduction
• Smith's Cloud: A High-velocity Cloud Colliding with the Milky Way
• The Galactic halo magnetic field revisited
• The Magnetohydrodynamics of Supersonic Gas Clouds: MHD Cosmic Bullets and Wind-Swept Clumps
• High-velocity clouds as streams of ionized and neutral gas in the halo of the Milky Way
• Discovery of a Population of HI Clouds in the Galactic Halo
• Filament formation in wind-cloud interactions. I. Spherical clouds in uniform magnetic fields
• The origin of the high-velocity cloud complex C
• Metallicity and Ionization in High Velocity Cloud Complex C
• On the Metallicity and Origin of the Smith High-Velocity Cloud
• Ionized Gas in the Smith Cloud
• Enhanced Cloud Disruption by Magnetic Field Interaction
• Head-Tail Clouds: Drops to Probe the Diffuse Galactic Halo
• The turbulent destruction of clouds - III. Three dimensional adiabatic shock-cloud simulations
• Measurement of a Magnetic Field in a Leading Arm High Velocity Cloud
• Milky Way Disk-Halo Transition in HI: Properties of the Cloud Population
• The Smith Cloud: high-velocity accretion and dark-matter confinement
• The Magellanic Stream: break up and accretion onto the hot Galactic corona
• Magnetized Gas in the Smith High Velocity Cloud
• The Smith Cloud and its dark matter halo: Survival of a Galactic disc passage
• Detection of a Coherent Magnetic Field in the Magellanic Bridge through Faraday Rotation
• Steady-State Magnetohydrodynamic Flow Around an Unmagnetized Conducting Sphere
• A comparison of shock-cloud and wind-cloud interactions: The longer survival of clouds in winds
• The post-infall evolution of a satellite galaxy
• The interaction of a magnetohydrodynamical shock with a filament
• The Effect of Mixing on the Observed Metallicity of the Smith Cloud

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• On the dynamics and survival of fractal clouds in galactic winds
• The Sagittarius dwarf galaxy: Where did all the gas go?
• The Launching of Cold Clouds by Galaxy Outflows III: The Influence of Magnetic Fields
• GASKAP-HI Pilot Survey Science I: ASKAP Zoom Observations of HI Emission in the Small Magellanic Cloud
• Cloudy with A Chance of Rain: Accretion Braking of Cold Clouds
• The Circumgalactic Medium of Milky Way-like Galaxies in the TNG50 Simulation -- II: Cold, Dense Gas Clouds and High-Velocity Cloud Analogs
• The Magellanic System: the puzzle of the leading gas stream
• Shock-multicloud interactions in galactic outflows -- I. Cloud layers with log-normal density distributions
• Constraining the Magnetic Field of the Smith High Velocity Cloud using Faraday rotation
• Efficiency of Thermal Conduction in a Magnetised Circumgalactic Medium
• Mass, Morphing, Metallicities: The Evolution of Infalling High Velocity Clouds
• Hydrodynamic Shielding and the Survival of Cold Streams
• The observable properties of cool winds from galaxies, AGN, and star clusters -- II. 3D models for the multiphase wind of M82
• The Smith Cloud: surviving a high speed transit of the Galactic disc
• The effect of rotation on the thermal instability of stratified galactic atmospheres - II. The formation of High Velocity Clouds
• Magnetic field draping around clumpy high-velocity clouds in galactic halo
• The role of the halo magnetic field on accretion through High-Velocity Clouds
• Exploring Hydrodynamic Instabilities along the Infalling High-Velocity Cloud Complex A
• Strength in numbers: A multiphase wind model with multiple cloud populations
• The isothermal evolution of a shock-filament interaction
• Distant probes of RM structure -- Where is the Faraday Rotation towards the Magellanic Leading Arm?
• The Observed O VI is Just the Tip of the Iceberg: Estimating the Hidden Material in Circumgalactic and Intergalactic Clouds