Galaxy motions in the Bootes strip

TL;DR

This study investigates the structure and motions of galaxies in the Bootes strip, revealing galaxy groupings, peculiar velocities, and mass estimates, contributing to understanding local cosmic flows and mass distribution.

Contribution

It provides detailed analysis of galaxy distribution, velocities, and mass in the Bootes strip, highlighting its lower dark matter density compared to the cosmic average.

Findings

Galaxies show Virgo-centric infall and outflow from the Local Void.

Most galaxies are in groups or pairs, with the main group around NGC5846.

The total dark matter density in the filament is about a third of the cosmic average.

Abstract

We explore the structure and kinematics of a dispersed filament of galaxies residing between the Local Void and the Virgo cluster. For such purpose, we consider a sample of 361 galaxies with radial velocities $V_{LG} < 2000$ km/s inside the sky area of RA = [13.0 ... 18.0]$^h$ and Dec. = [$-$5 ... $+$10]$^\circ$. At present, 161 of them have individual distance estimates. The galaxy distribution on peculiar velocities along the strip exhibits the known Virgo-centric infall at RA < 14$^h$ and some signs of outflow from the Local Void at RA > 17$^h$. Majority of the Bootes strip galaxies (56%) belong to 13 groups and 11 pairs, with the most prominent group around NGC5846. The Bootes strip groups reside within [17$-$27]Mpc, being all farther from us than the Virgo cluster. The Bootes filament contains the total stellar mass of $2.7\times10^{12} M_\odot$ and the total virial mass of $9.07\times10^{13} M_\odot$, having the average density of dark matter to be $\Omega_m = 0.09$, i.e. a factor three lower than the global cosmic average.