Structure and kinematics of the Virgo cluster of galaxies^⋆

¹ Special Astrophysical Observatory of the Russian Academy of Sciences, Nizhnij Arkhyz, Karachay-Cherkessia 369167, Russia
e-mail: phiruzi@gmail.com
² Main Astronomical Observatory of the National Academy of Sciences, 27 Akademika Zabolotnoho St., Kyiv 03143, Ukraine

Received: 25 June 2019
Accepted: 24 January 2020

Abstract

Aims. This work considers the Virgo cluster of galaxies, focusing on its structure, kinematics, and morphological landscape. Our principal aim is to estimate the virial mass of the cluster. For this purpose, we present a sample of 1537 galaxies with radial velocities V_LG <  2600 km s⁻¹ situated within a region of ΔSGL = 30° and ΔSGB = 20° around M 87. About half of the galaxies have distance estimates.

Methods. We selected 398 galaxies with distances in a (17 ± 5) Mpc range. Based on their 1D and 2D number-density profiles and their radial velocity dispersions, we made an estimate for the virial mass of the Virgo cluster.

Results. We identify the infall of galaxies towards the Virgo cluster core along the Virgo Southern Extension filament. From a 1D profile of the cluster, we obtain the virial mass estimate of (6.3 ± 0.9)×10¹⁴ M_⊙, which is in tight agreement with its mass estimate via the external infall pattern of galaxies.

Conclusions. We conclude that the Virgo cluster outskirts between the virial radius and the zero-velocity radius do not contain significant amounts of dark matter beyond the virial radius.