Collisions between Dark Matter Confined High Velocity Clouds and Magnetized Galactic Disks: The Smith Cloud

Abstract

The Galaxy's population of High Velocity Clouds (HVCs) may include a subpopulation that is confined by dark matter minihalos and falling toward the Galactic disk. We present the first magnetohydrodynamic simulational study of dark matter-dominated HVCs colliding with a weakly magnetized galactic disk. Our HVCs have baryonic masses of $5\times 10^6$M${}_{\odot }$ and dark matter minihalo masses of 0, $3\times 10^8$, or $1\times 10^9$M${}_{\odot }$. They are modeled on the Smith Cloud, which is said to have collided with the disk 70 Myr ago. We find that, in all cases, the cloud's collision with the galactic disk creates a hole in the disk, completely disperses the cloud, and forms a bubble-shaped structure on the far side of the disk. In contrast, when present, the dark matter minihalo continues unimpeded along its trajectory. Later, as the minihalo passes through the bubble structure and galactic halo, it accretes up to $6.0\times 10^5$M${}_{\odot }$ in baryonic material, depending on the strengths of the magnetic field and minihalo gravity. These simulations suggest that if the Smith Cloud is associated with a dark matter minihalo and collided with the Galactic disk, the minihalo has accreted the observed gas. However, if the Smith Cloud is dark matter-free, it is on its first approach toward the disk. These simulations also suggest that the dark matter is most concentrated either at the head of the cloud or near the cloud, depending upon the strength of the magnetic field, a point that could inform indirect dark matter searches.

5 pages, 4 figures, 1 table

References in corpus (9)

• The COS/UVES Absorption Survey of the Magellanic Stream. III: Ionization, Total Mass, and Inflow Rate onto the Milky Way
• Smith's Cloud: A High-velocity Cloud Colliding with the Milky Way
• A Catalog of Ultra-compact High Velocity Clouds from the ALFALFA Survey: Local Group Galaxy Candidates?
• Ionized Gas in the Smith Cloud
• Relics of structure formation: extra-planar gas and high-velocity clouds around the Andromeda Galaxy
• The Smith Cloud and its dark matter halo: Survival of a Galactic disc passage
• Structure of Supergiant Shells in the Large Magellanic Cloud
• Potential Condensed Fuel for the Milky Way
• Discovery of Star Formation in the Extreme Outer Galaxy Possibly Induced by a High-velocity Cloud Impact

Cited by in corpus (24)

• Tidal dissipation in rotating fluid bodies: the presence of a magnetic field
• Intermediate- and high-velocity clouds in the Milky Way II: evidence for a Galactic fountain with collimated outflows and diffuse inflows
• Cloudy with A Chance of Rain: Accretion Braking of Cold Clouds
• Dynamical tides in exoplanetary systems containing Hot Jupiters: confronting theory and observations
• The Magellanic System: the puzzle of the leading gas stream
• CHANG-ES XXIII: Influence of a galactic wind in NGC 5775
• Constraining the Magnetic Field of the Smith High Velocity Cloud using Faraday rotation
• Mass, Morphing, Metallicities: The Evolution of Infalling High Velocity Clouds
• Exploring the Dust Content of Galactic Halos with Herschel III. NGC 891
• The Smith Cloud: surviving a high speed transit of the Galactic disc
• Hot-Jupiter Core Mass from Roche-lobe Overflow
• The Effect of Mixing on the Observed Metallicity of the Smith Cloud
• The role of the halo magnetic field on accretion through High-Velocity Clouds
• High-energy radiation from collisions of high velocity clouds and the Galactic disk
• VERA astrometry toward the Perseus arm gap
• Synchrotron Emission from Dark Matter in Galactic Subhalos. A Look into the Smith Cloud
• An Intermediate Velocity HI Cloud Falling to the Galactic Disk; Possible Evidence for Low Metallicity HI Gas Originated Outside the Galactic Disk
• A Component of the Smith High Velocity Cloud Now Crossing the Galactic Plane
• A New Search for Star Forming Regions in the Southern Outer Galaxy
• The Long Tails of the Pegasus-Pisces Arch Intermediate Velocity Cloud
• Cosmic Rays and Non-thermal Emission Induced by Accretion of Cool Gas onto the Galactic Disk
• The Observed O VI is Just the Tip of the Iceberg: Estimating the Hidden Material in Circumgalactic and Intergalactic Clouds
• Interaction Between Rogue HI Clouds and the Magnetic Field High Above the Galaxy
• Simulating High-Velocity Clouds in the Observational Plane: An Initial Study with the Smith Cloud