2013MNRAS.433.1287S

Star formation (SF) 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 SF-density relation have been observed in a few z > 1.4 clusters. Using deep imaging from 100-500µm from Photodetector Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging REceiver (SPIRE) onboard Herschel, we investigate infrared properties of spectroscopic and photo-z cluster members, and of Hα 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 (SED) in the rest-frame 8-1000µm. We measure total IR luminosity, deriving star formation rates (SFRs) ranging from 89 to 463M☉yr-1 for 13 galaxies individually detected by Herschel, all located beyond the core region (r >250kpc). We perform a stacking analysis of nine star-forming members not detected by PACS, yielding a detection with SFR = 48±16M☉yr-1. Using a colour 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.