On the origin of anomalous velocity clouds in the Milky Way

Abstract

We report that neutral hydrogen (HI) gas clouds, resembling High Velocity Clouds (HVCs) observed in the Milky Way (MW), appear in MW-sized disk galaxies formed in high-resolution Lambda Cold Dark Matter (LCDM) cosmological simulations which include gas-dynamics, radiative cooling, star formation, supernova feedback, and metal enrichment. Two such disk galaxies are analyzed, and HI column density and velocity distributions in all-sky Aitoff projections are constructed. The simulations demonstrate that LCDM is able to create galaxies with sufficient numbers of anomalous velocity gas clouds consistent with the HVCs observed within the MW, and that they are found within a galactocentric radius of 150 kpc. We also find that one of the galaxies has a polar gas ring, with radius 30 kpc, which appears as a large structure of HVCs in the Aitoff projection. Such large structures may share an origin similar to extended HVCs observed in the MW, such as Complex C.

arXiv commentAccepted by ApJL, 08 Jun 2006. 5 pages, 5 figures, 1 table. LaTeX (emulateapj.cls). File with high resolution images available at http://astronomy.swin.edu.au/~tconnors/publications/ . References added; discussion added to, but conclusions unchanged

References in corpus (19)

• Multi-Phase Galaxy Formation: High Velocity Clouds and the Missing Baryon Problem
• High Velocity Clouds: Building Blocks of the Local Group
• Distances and Metallicities of High- and Intermediate-Velocity Clouds
• N-body Simulations of the Small Magellanic Cloud and the Magellanic Stream
• GCD+: A New Chemodynamical Approach to Modeling SNe and Chemical Enrichment
• On the Continuing Formation of the Andromeda Galaxy: Detection of HI Clouds in the M31 Halo
• The Escape of Ionizing Photons from the Galaxy
• HIPASS High-Velocity Clouds: Properties of the Compact and Extended Populations
• Internal Alignment of the Halos of Disk Galaxies in Cosmological Hydrodynamic Simulations
• The Diversity of High- and Intermediate-Velocity Clouds: Complex C versus IV Arch
• Westerbork HI observations of high-velocity clouds near M31 and M33
• Where are the high velocity clouds?
• The Galactic Nature of High Velocity Cloud Complex WB
• High-Velocity Cloud Complex C: Galactic Fuel or galactic Waste?
• A Very Sensitive 21cm Survey for Galactic High-Velocity HI
• OVI, NV, and CIV in the Galactic Halo: I. Velocity-Dependent Ionization Models
• Where are the High Velocity Clouds in Local Group Analogs?
• The Absence of Stars in Compact High-Velocity Clouds
• A Search for Stellar Populations in High Velocity Clouds

Cited by in corpus (15)

• Gaseous Galaxy Halos
• Seeding the formation of cold gaseous clouds in Milky Way size halos
• Smith's Cloud: A High-velocity Cloud Colliding with the Milky Way
• The Formation of Polar Disk Galaxies
• The SAMI Galaxy Survey: Stellar and gas misalignments and the origin of gas in nearby galaxies
• Ongoing Galactic Accretion: Simulations and Observations of Condensed Gas in Hot Halos
• The role of gas infall in the evolution of disc galaxies
• Chemodynamical analysis of bulge stars for simulated disc galaxies
• Thermal Instability in the CGM of $L_{\star }$ Galaxies: Testing "Precipitation" Models with the FIRE Simulations
• Metallicity gradients of disc stars for a cosmologically simulated galaxy
• Do High-Velocity Clouds trace the Dark Matter subhalo population?
• Neutral hydrogen in galactic fountains
• On the Origin of High-velocity Clouds in the Galaxy
• An Intermediate Velocity HI Cloud Falling to the Galactic Disk; Possible Evidence for Low Metallicity HI Gas Originated Outside the Galactic Disk
• Spatial environment of polar-ring galaxies from the SDSS