Galaxy clustering in the VVV Near-IR Galaxy Catalogue

TL;DR

This paper uses multiple clustering algorithms on the VVV Near-IR Galaxy Catalogue to identify galaxy overdensities in the Zone of Avoidance, providing new candidate structures for further study.

Contribution

It applies and compares several clustering methods to identify galaxy groups in a challenging low-latitude region, highlighting robust candidates for real galaxy overdensities.

Findings

Nineteen galaxy systems identified by all methods.

High probability that these systems are genuine overdensities.

Emphasizes need for spectroscopic follow-up.

Abstract

Mapping galaxies at low Galactic latitudes and determining their clustering status are fundamental steps in defining the large-scale structure in the nearby Universe. The VVV Near-IR Galaxy Catalogue (VVV NIRGC) allows us to explore this region in great detail. Our goal is to identify galaxy overdensities and characterize galaxy clustering in the Zone of Avoidance. We use different clustering algorithms to identify galaxy overdensities: the Voronoi tessellations, the Minimum Spanning Tree and the Ordering Points To Identify the Clustering Structure. We studied the membership, isolation, compactness, and flux limits to identify compact groups of galaxies. Each method identified a variety of galaxy systems across the Galactic Plane that are publicly available.We also explore the probability that these systems are formed by concordant galaxies using mock catalogues. Nineteen galaxy systems were identified in all of the four methods. They have the highest probability to be real overdensities. We stress the need for spectroscopic follow-up observations to confirm and characterize these new structures.