Properties of star-forming galaxies in a cluster and its surrounding structure at z=1.46

TL;DR

This study investigates star-forming galaxies in a z=1.46 galaxy cluster, revealing filamentary structures, the presence of AGN-hosting red galaxies, and high star formation rates comparable to the field, suggesting early cluster galaxy evolution.

Contribution

First detailed narrow-band survey of [OII] emitters in a z=1.46 cluster, linking galaxy distribution, star formation, and AGN activity in high-density environments.

Findings

[OII] emitters form filamentary structures around the cluster.

High fraction of red [OII] emitters likely hosting AGNs.

Star formation rates in the cluster core are comparable to the field at z=1.46.

Abstract

We conduct a narrow-band imaging survey of [OII] emitters over a 32'x23' area in and around the XMMXCS J2215.9-1738 cluster at z=1.46 with Subaru/Suprime-Cam, and select 380 [OII] emitting galaxies down to 1.4E-17 erg/s/cm2. Among them, 16 [OII] emitters in the cluster central region are confirmed by NIR spectroscopy with Subaru/MOIRCS. We find that [OII] emitters are distributed along filamentary large-scale structures around the cluster. The z'-K vs K colour-magnitude diagram shows that a significantly higher fraction of [OII] emitters is seen on the red sequence in the cluster core than in other environments we define in this paper. It is likely that these red galaxies are nearly passively evolving galaxies which host [OII] emitting AGNs, rather than dust-reddened star-forming galaxies. We argue therefore that AGN feedback may be one of the critical processes to quench star formation in massive galaxies in high density regions. We also find that the cluster has experienced high star formation activities at rates comparable to that in the field at z=1.46. In addition, a mass-metallicity relation exists in the cluster at z=1.46, which is similar to that of star-forming galaxies in the field at z~2. These results all suggest that at z~1.5 star formation activity in the cluster core becomes as high as those in low density environments and there is apparently not yet a strong environmental dependence, except for the red emitters.