Evidence for high-velocity inflow of neutral hydrogen toward the galaxy

The results of an extended search and mapping of very high velocity clouds in a large area of the sky around the direction to the galactic center are reported. About 2000 positions were surveyed using the 43 m radio telescope of NRAO with an rms noise of 0.03 K on a velocity interval of -1000 to +1000 km/s. A vast population of high velocity clouds with negative velocities and rather small angular sizes are found in the observed area; 85 percent of all the clouds with velocities greater than 80 km/s are moving away from the sun and 15 percent are moving toward it. This preponderance of inward motions with similar extreme velocities in the galactic center and anticenter is strong evidence for a high-velocity inflow of neutral hydrogen toward the Milky Way.