Suppression of Star Formation in the central 200 kpc of a z = 1.4 Galaxy
  Cluster [Erratum added]
  We present the results of an extended narrow-band H{\alpha} study of the
massive galaxy cluster XMMU J2235.3-2557 at z = 1.39. This paper represents a
follow up study to our previous investigation of star-formation in the cluster
centre, extending our analysis out to a projected cluster radius of 1.5 Mpc.
Using the Near InfraRed Imager and Spectrograph (NIRI) on Gemini North we
obtained deep H narrow-band imaging corresponding to the rest-frame wavelength
of H{\alpha} at the cluster's redshift. We identify a total of 163 potential
cluster members in both pointings, excluding stars based on their near-IR
colours derived from VLT/HAWK-I imaging. Of these 163 objects 14 are
spectroscopically confirmed cluster members, and 20% are excess line-emitters.
We find no evidence of star formation activity within a radius of 200 kpc of
the brightest cluster galaxy in the cluster core. Dust-corrected star formation
rates (SFR) of excess emitters outside this cluster quenching radius, RQ \sim
200 kpc, are on average <SFR> = 2.7 \pm 1.0 M\odot yr-1, but do not show
evidence of increasing star-formation rates toward the extreme 1.5 Mpc radius
of the cluster. No individual cluster galaxy exceeds an SFR of 6 M\odot yr-1 .
Massive galaxies (log M\ast /M\odot > 10.75) all have low specific SFRs (SSFRs,
i.e. SFR per unit stellar mass). At fixed stellar mass, galaxies in the cluster
centre have lower SSFRs than the rest of the cluster galaxies, which in turn
have lower SSFRs than field galaxies at the same redshift by a factor of a few
to 10. For the first time we can demonstrate through measurements of individual
SFRs that already at very early epochs (at an age of the Universe of \sim4.5
Gyr) the suppression of star-formation is an effect of the cluster environment
which persists at fixed galaxy stellar mass. [Erratum added after the original
paper]
