Discovery of a supercluster candidate at $z \sim 1.1$

TL;DR

This paper reports the discovery of a distant supercluster candidate at redshift approximately 1.1 in the Dark Energy Survey data, highlighting its significance, estimated mass, and potential cosmological implications.

Contribution

It presents the identification and characterization of a supercluster candidate at z~1.1 using galaxy density maps, a novel detection at such high redshift with regular galaxies.

Findings

Most significant overdense region at 3σ significance

Estimated supercluster mass of about 1.37×10^{17} solar masses

Potentially the most distant supercluster identified by regular galaxies

Abstract

We report a promising candidate for a distant supercluster at z $\sim 1.1$ in the Dark Energy Survey Science Verification data. We examine smoothed semi-3D galaxy density maps in various photo-z slices. Among several overdense regions, in this work we report the most significant one as having a $3\sigma$ overdensity at a redshift of $\sim1.1$, over a $\sim160$ Mpc scale, much larger than the regular cluster scale (several Mpc). The shape of the supercluster is not circular in the sky projection. Therefore, we regard the point of maximum overdensity as the center for quantitative measurements. Two different estimates suggest the mass of the supercluster to be $1.37\substack{+1.31 \\ -0.79} \times 10^{17} M_{\odot}$, more than one order more massive than regular galaxy clusters. Except for protosuperclusters found with emission-line galaxies, this could be the most distant supercluster to date defined by regular galaxies. A spectroscopic confirmation would make this a very interesting object for cosmology. We discuss the possible implications of such a massive structure for $\Lambda$CDM cosmology.