A Catalog of Neighboring Galaxies

Abstract

We present an all-sky catalog of 451 nearby galaxies, each having an individual distance estimate D ≲ 10 Mpc or a radial velocity VLG < 550 km s-1. The catalog contains data on basic optical and H I properties of the galaxies, in particular, their diameters, absolute magnitudes, morphological types, circumnuclear region types, optical and H I surface brightnesses, rotational velocities, and indicative mass-to-luminosity and H I mass-to-luminosity ratios, as well as a so-called tidal index, which quantifies the galaxy environment. We expect the catalog completeness to be roughly 70%–80% within 8 Mpc. About 85% of the Local Volume population are dwarf (dIr, dIm, and dSph) galaxies with MB > -17.0, which contribute about 4% to the local luminosity density, and roughly 10%–15% to the local H I mass density. The H I mass-to-luminosity and the H I mass-to-total (indicative) mass ratios increase systematically from giant galaxies toward dwarfs, reaching maximum values about 5 in solar units for the most tiny objects. For the Local Volume disklike galaxies, their H I masses and angular momentum follow Zasov's linear relation, expected for rotating gaseous disks being near the threshold of gravitational instability, favorable for active star formation. We found that the mean local luminosity density exceeds 1.7–2.0 times the global density, in spite of the presence of the Tully void and the absence of rich clusters in the Local Volume. The mean local H I density is 1.4 times its "global" value derived from the H I Parkes Sky Survey. However, the mean local baryon density Ωb(< 8 Mpc) = 2.3% consists of only a half of the global baryon density, Ωb = (4.7 ± 0.6)% (Spergel et al., published in 2003). The mean-square pairwise difference of radial velocities is about 100 km s-1 for spatial separations within 1 Mpc, increasing to ∼300 km s-1 on a scale of ∼3 Mpc. also We calculated the integral area of the sky occupied by the neighboring galaxies. Assuming the H I size of spiral and irregular galaxies to be 2.5 times their standard optical diameter and ignoring any evolution effect, we obtain the expected number of the line-of-sight intersections with the H I galaxy images to be dn/dz ∼ 0.4, which does not contradict the observed number of absorptions in QSO spectra.