Structure and kinematics of the Bootes filament

TL;DR

This study maps the structure and motion of galaxies in the Bootes filament, revealing galaxy groupings, infall patterns, and mass estimates, highlighting its lower dark matter density compared to the cosmic average.

Contribution

It provides detailed analysis of galaxy distribution, kinematics, and mass in the Bootes filament, including new insights into its structure and dark matter content.

Findings

Detection of Virgo-centric infall and outflow from the Local Void.

Identification of galaxy groups, pairs, and field galaxies.

Mass estimates indicating lower dark matter density than the cosmic average.

Abstract

Bootes filament of galaxies is a dispersed chain of groups residing on sky between the Local Void and the Virgo cluster. We consider a sample of 361 galaxies inside the sky area of $RA = 13.0^h ... 18.5^h$ and $Dec = -5^\circ ... +10^\circ$ with radial velocities $V_{LG} < 2000$ km/s to clarify its structure and kinematics. In this region, 161 galaxies have individual distance estimates. We use these data to draw the Hubble relation for galaxy groups, pairs as well as the field galaxies, and to examine the galaxy distribution on peculiar velocities. Our analysis exposes the known Virgo-centric infall at $RA < 14^h$ and some signs of outflow from the Local Void at $RA > 17^h$. According to the galaxy grouping criterion, this complex contains the members of 13 groups, 11 pairs and 140 field galaxies. The most prominent group is dominated by NGC5846. 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 value.