Mining the Local Volume

TL;DR

This paper reviews recent discoveries and measurements of galaxies within 10 Mpc, revealing insights into local cosmology, galaxy properties, and the universe's vacuum dominance on small scales.

Contribution

It provides new data on local galaxy distances, star formation histories, and cosmological parameters, and introduces a novel method for estimating group masses from cold infall patterns.

Findings

Local galaxy count increased from 179 to 550.

Hubble flow around local groups is very quiet, indicating vacuum dominance.

HI mass and angular momentum follow a linear relation in late-type galaxies.

Abstract

After recent systematic optical, IR, and HI surveys, the total number of known galaxies within 10 Mpc has increased from 179 to 550. About half this Local Volume (LV) sample is now been imaged with HST, yielding the galaxy distances with an accuracy of about 8%. For the majority of the LV galaxies we currently have H-alpha fluxes that allow us to reconstruct the star formation history of our neighbourhood. For the late-type LV galaxies their HI masses and angular momentum follow the linear relation in the range of 4 orders, which is expected for rotating gaseous disks being near the gravitational instability threshold. The data obtained on the LV galaxies imply important cosmological parameters, in particular, the mean local matter density and HI mass density, as well as SFR density. Surprisingly, the local Hubble flow around the LV groups is very quiet, with 1D rms deviations of 25 km/s,which is a signature of the Universe vacuum-dominated on small scales. The cold infall pattern around nearby groups provides us with a new method to determine the total mass of the groups independent from virial mass estimates.