Surveying the Local Supercluster Plane

TL;DR

This survey analyzes galaxy distribution and velocities along the Local supercluster plane, estimating Virgo cluster mass and infall patterns, revealing insights into galaxy clustering, peculiar velocities, and dark matter distribution.

Contribution

It provides a comprehensive analysis of galaxy velocities and distribution in the Local supercluster, estimating Virgo's mass and infall dynamics, with new insights into dark matter extent.

Findings

Virgo cluster mass estimated at (7.4±0.9)×10^{14} M_sun

Galaxies around Virgo show Virgocentric infall of about 500 km/s

The zero-velocity surface radius is approximately 7.0 Mpc

Abstract

We investigate the distribution and velocity field of galaxies situated in a band of 100 by 20 degrees centered on M87 and oriented along the Local supercluster plane. Our sample amounts 2158 galaxies with radial velocities less than 2000 km/s. Of them, 1119 galaxies (52%) have distance and peculiar velocity estimates. About 3/4 of early-type galaxies are concentrated within the Virgo cluster core, most of the late-type galaxies in the band locate outside the virial radius. Distribution of gas-rich dwarfs with $M_{\rm H\,I} > M_*$ looks to be insensitive to the Virgo cluster presence. Among 50 galaxy groups in the equatorial supercluster band 6 groups have peculiar velocities about 500-1000 km/s comparable with virial motions in rich clusters. The most cryptic case is a flock of nearly 30 galaxies around NGC4278 (Coma I cloud), moving to us with the mean peculiar velocity of $-$840 km/s. This cloud (or filament?) resides at a distance of 16.1 Mpc from us and approximately 5 Mpc away from the Virgo center. Galaxies around Virgo cluster exhibit Virgocentric infall with an amplitude of about 500 km/s. Assuming the spherically symmetric radial infall, we estimate the radius of the zero-velocity surface to be $R_0 = (7.0\pm0.3)$ Mpc that yields the total mass of Virgo cluster to be $(7.4\pm0.9)\times 10^{14} M_{\odot}$ in tight agreement with its virial mass estimates. We conclude that the Virgo outskirts does not contain significant amounts of dark mater beyond its virial core.