A Catalog of Neighboring Galaxies

Abstract

We present an all-sky catalog of 451 nearby galaxies, each having an individual distance estimate D\r ##IMG## [http://ej.iop.org/icons/Entities/lesssim.gif] {lesssim} 10 Mpc or a radial velocity V LG -17.0, which contribute\r about 4% to the local luminosity density, and roughly 10%–15% to the local H I mass density. The H I\r mass-to-luminosity and the H I mass-to-total (indicative) mass ratios increase systematically from\r giant galaxies toward dwarfs, reaching maximum values about 5 in solar units for the most tiny\r objects. For the Local Volume disklike galaxies, their H I masses and angular momentum follow\r Zasov's linear relation, expected for rotating gaseous disks being near the threshold of\r gravitational instability, favorable for active star formation. We found that the mean local\r luminosity density exceeds 1.7–2.0 times the global density, in spite of the presence of the Tully\r void and the absence of rich clusters in the Local Volume. The mean local H I density is 1.4 times\r its "global" value derived from the H I Parkes Sky Survey. However, the mean local baryon density Ω\r b (< 8 Mpc) = 2.3% consists of only a half of the global baryon density, Ω b = (4.7 ± 0.6)% (Spergel\r et al., published in 2003). The mean-square pairwise difference of radial velocities is about 100 km\r s -1 for spatial separations within 1 Mpc, increasing to ~300 km s -1 on a scale of ~3 Mpc. also We\r calculated the integral area of the sky occupied by the neighboring galaxies. Assuming the H I size\r of spiral and irregular galaxies to be 2.5 times their standard optical diameter and ignoring any\r evolution effect, we obtain the expected number of the line-of-sight intersections with the H I\r galaxy images to be dn / dz ~ 0.4, which does not contradict the observed number of absorptions in\r QSO spectra.