Structure and dynamics of the supercluster of galaxies SC0028-0005

TL;DR

This study analyzes the structure and dynamics of the supercluster SC0028-0005 at redshift 0.22, using multi-wavelength data and dynamical models to confirm its collapsing state and estimate its mass distribution.

Contribution

It provides a detailed dynamical analysis of a supercluster, combining photometric, spectroscopic, and weak-lensing data to characterize its mass and collapse status.

Findings

SC0028-0005 is a collapsing supercluster.

Mass within 10 Mpc is estimated between 4 and 16 x 10^15 solar masses.

Total mass of the supercluster is approximately 4.6 to 16 x 10^17 solar masses.

Abstract

According to the standard cosmological scenario, superclusters are objects that have just passed the turn around point and are collapsing. The dynamics of very few superclusters have been analysed up to now. In this paper we study the supercluster SC0028-0005, at redshift 0.22, identify the most prominent groups and/or clusters that make up the supercluster, and investigate the dynamic state of this structure. For the membership identification, we have used photometric and spectroscopic data from SDSS-DR10, finding 6 main structures in a flat spatial distribution. We have also used a deep multi-band observation with MegaCam/CFHT to estimate de mass distribution through the weak-lensing effect. For the dynamical analysis, we have determined the relative distances along the line of sight within the supercluster using the Fundamental Plane of early-type galaxies. Finally, we have computed the peculiar velocities of each of the main structures. The 3D distribution suggests that SC0028-005 is indeed a collapsing supercluster, supporting the formation scenario of these structures. Using the spherical collapse model, we estimate that the mass within $r = 10$~Mpc should lie between 4 and $16 \times 10^{15} M_\odot$. The farthest detected members of the supercluster suggest that within $\sim 60$~Mpc the density contrast is $\delta \sim 3$ with respect to the critical density at $z=0.22$, implying a total mass of $\sim 4.6$--$16 \times 10^{17} M_\odot$, most of which in the form of low-mass galaxy groups or smaller substructures.