The Space Density of Primordial Gas Clouds near Galaxies and Groups and their Relation to Galactic HVCs

Abstract

The Arecibo HI Strip Survey probed the halos of ~300 cataloged galaxies and the environments of ~14 groups with sensitivity to neutral hydrogen masses > 10^7 M_sun. The survey detected no objects with properties resembling the High Velocity Clouds (HVCs) associated with the Milky Way or Local Group. If the HVCs were typically M_HI=10^{7.5} M_sun objects distributed throughout groups and galaxy halos at distances of 1 Mpc, the survey should have made ~70 HVC detections in groups and ~250 detections around galaxies. The null detection implies that HVCs are deployed at typical distances of <200 kpc from the galaxies or group barycenters. If the clouds are in virial equilibrium, their average dark matter fraction must be 98% or higher.

Accepted for publication in ApJL. 7 pages, 2 figures

Cited by in corpus (30)

• Highly-Ionized High-Velocity Gas in the Vicinity of the Galaxy
• Properties of galaxy dark matter halos from weak lensing
• X-ray Properties of Groups of Galaxies
• Complex C: A Low-Metallicity High-Velocity Cloud Plunging into the Milky Way
• New perspectives on strong z=0.5 MgII absorbers: are halo-mass and equivalent width anti-correlated?
• Atomic Hydrogen Gas in Dark-Matter Minihalos and the Compact High Velocity Clouds
• The Kinematics of Intermediate Redshift Mg II Absorbers
• A Broad Search for Counterrotating Gas and Stars: Evidence for Mergers and Accretion
• The abundance of dark galaxies
• A Very Sensitive 21cm Survey for Galactic High-Velocity HI
• A Targeted Survey for HI Clouds in Galaxy Groups
• An HI survey of six Local Group analogs: I. Survey description and the search for high-velocity clouds
• Where are the High Velocity Clouds in Local Group Analogs?
• An Extragalactic HI Cloud with No Optical Counterpart?
• On the Neutral Gas Content and Environment of NGC 3109 and the Antlia Dwarf Galaxy
• An HI survey of the Centaurus and Sculptor Groups - Constraints on the space density of low mass galaxies
• A Limit on the Metallicity of Compact High Velocity Clouds
• LCDM Satellites and HI Companions - The Arecibo ALFA Survey of NGC 2903
• Absorption Line Study of Halo Gas in NGC 3067 Toward the Background Quasar 3C 232
• The Cosmological Significance of High-Velocity Cloud Complex H
• SDSS Survey for Resolved Milky Way Satellite Galaxies II: High-Velocity Clouds in the Early Data Release
• QSO Absorption Line Constraints on Intragroup High-Velocity Clouds
• Status of HI searches for CHVCs beyond the Local Group
• An HI View of Galaxy Conformity: HI-rich Environment around HI-excess Galaxies
• Is GBT 1355+5439 a dark galaxy?
• From gas to galaxies
• Detecting Dark Matter in High Velocity Clouds
• High Velocity Cloud Edges and Mini-HVCs
• The HI Detection of Low Column Density Clouds and Galaxies
• Free-Floating HI Clouds in the M 81 Group