Distant galaxy clusters in the COSMOS field found by HIROCS

TL;DR

This paper reports the discovery of 12 high-redshift galaxy cluster candidates in the COSMOS field using the HIROCS survey, revealing a trend of increasing blue galaxy fraction and signs of galaxy interactions at higher redshifts.

Contribution

First high-redshift galaxy cluster candidate sample from HIROCS in the COSMOS field, combining public and proprietary data to identify clusters at z=1.23-1.55.

Findings

12 cluster candidates identified at z=1.23-1.55

Increasing blue galaxy fraction with redshift

Presence of disturbed and interacting galaxies

Abstract

We present the first high-redshift galaxy cluster candidate sample from the HIROCS survey found in the COSMOS field. It results from a combination of public COSMOS with proprietary H-band data on a 0.66 square degree part of the COSMOS field and comprises 12 candidates in the redshift range 1.23 < z < 1.55. We find an increasing fraction of blue cluster members with increasing redshift. Many of the blue and even some of the reddest member galaxies exhibit disturbed morphologies as well as signs of interaction.