Dust-obscured star-formation in the outskirts of XMMU J2235.3-2557, a massive galaxy cluster at z=1.4

TL;DR

This study investigates star formation in the outskirts of a massive galaxy cluster at z=1.4 using Herschel infrared data, finding highly obscured star-forming galaxies but no reversal of the star-formation--density relation.

Contribution

It provides the first detailed infrared analysis of star formation in the outskirts of this distant, massive galaxy cluster, revealing obscured star-forming populations.

Findings

Detected 13 galaxies with high SFRs beyond the core

Stacking analysis indicates a significant population of obscured star-forming galaxies

No evidence found for reversal of the star-formation--density relation in this cluster

Abstract

Star-formation in the galaxy populations of local massive clusters is reduced with respect to field galaxies, and tends to be suppressed in the core region. Indications of a reversal of the star-formation--density relation have been observed in a few z >1.4 clusters. Using deep imaging from 100-500um from PACS and SPIRE onboard Herschel, we investigate the infrared properties of spectroscopic and photo-z cluster members, and of Halpha emitters in XMMU J2235.3-2557, one of the most massive, distant, X-ray selected clusters known. Our analysis is based mostly on fitting of the galaxies spectral energy distribution in the rest-frame 8-1000um. We measure total IR luminosity, deriving star formation rates (SFRs) ranging from 89-463 Msun/yr for 13 galaxies individually detected by Herschel, all located beyond the core region (r >250 kpc). We perform a stacking analysis of nine star-forming members not detected by PACS, yielding a detection with SFR=48 Msun/yr. Using a color criterion based on a star-forming galaxy SED at the cluster redshift we select 41 PACS sources as candidate star-forming cluster members. We characterize a population of highly obscured SF galaxies in the outskirts of XMMU J2235.3-2557. We do not find evidence for a reversal of the SF-density relation in this massive, distant cluster.