Star Formation in the XMMU J2235.3-2557 Galaxy Cluster at z=1.39

TL;DR

This study investigates star formation activity in a galaxy cluster at z=1.39 using narrow-band imaging, revealing that star formation is suppressed within 200 kpc of the cluster center, indicating early quenching processes.

Contribution

First narrow-band photometric analysis of star formation in XMMU J2235.3-2557 at z=1.39, demonstrating spatial dependence of star formation suppression in a high-redshift cluster.

Findings

Star formation is quenched within 200 kpc of the cluster center.

Brighter galaxies tend to have lower SFRs.

SFR correlates with distance from the cluster center.

Abstract

We present the first results of a narrow-band photometric study of the massive galaxy cluster XMMU J2235.3-2557 at z=1.39. We obtained deep $H$ narrow-band imaging with NIRI on Gemini North, corresponding to H-alpha emission at the cluster's redshift. Our sample consists of 82 galaxies within a radius of ~500 kpc, ten of which are spectroscopically confirmed cluster members. Sixteen galaxies are identified as excess line-emitters. Among just the excess line-emitting galaxies we find an average SFR of 3.6 +/- 1.3 Msun/yr. For spectroscopically confirmed cluster members we find a correlation between H broad-band magnitude and SFR such that brighter galaxies have lower SFRs. The probability that SFR and magnitude of confirmed members are uncorrelated is 0.7%. We also find a correlation between SFR and distance from the cluster centre for both confirmed and excess line-emitting candidate members, with a probability of 5% for there to be no correlation among confirmed members. All excess line-emitting candidate cluster members are located outside a radius of 200 kpc. We conclude that star formation is effectively shut off within the central 200 kpc radius (R_QUENCH ~ 200 kpc) of this massive galaxy cluster at z=1.39, when the universe was only 4.5 Gyr old.