The Type II Supernova Rate in z~0.1 Galaxy Clusters from the Multi-Epoch
  Nearby Cluster Survey
  We present 7 spectroscopically confirmed Type II cluster supernovae (SNeII)
discovered in the Multi-Epoch Nearby Cluster Survey, a supernova survey
targeting 57 low redshift 0.05 < z < 0.15 galaxy clusters with the
Canada-France-Hawaii Telescope. We find the rate of Type II supernovae within
the virial radius of these galaxy clusters to be 0.026 (+0.085 -0.018 stat;
+0.003 -0.001 sys) SNe per century per 1e10 solar masses. Surprisingly, one
SNII is in a red sequence host galaxy that shows no clear evidence of recent
star formation. This is unambiguous evidence in support of ongoing, low-level
star formation in at least some cluster elliptical galaxies, and illustrates
that galaxies that appear to be quiescent cannot be assumed to host only Type
Ia SNe. Based on this single SNII we make the first measurement of the SNII
rate in red sequence galaxies, and find it to be 0.007 (+0.014 -0.007 stat;
+0.009 -0.001 sys) SNe per century per 1e10 solar masses. We also make the
first derivation of cluster specific star formation rates (sSFR) from cluster
SNII rates. We find that for all galaxy types, sSFR is 5.1 (+15.8 -3.1 stat;
+0.9 -0.9 sys) solar masses per year per 1e12 solar masses, and for red
sequence galaxies only, it is 2.0 (+4.2 -0.9 stat; +0.4 -0.4 sys) solar masses
per year per 1e12 solar masses. These values agree with SFRs measured from
infrared and ultraviolet photometry, and H-alpha emission from optical
spectroscopy. Additionally, we use the SFR derived from our SNII rate to show
that although a small fraction of cluster Type Ia SNe may originate in the
young stellar population and experience a short delay time, these results do
not preclude the use of cluster SNIa rates to derive the late-time delay time
distribution for SNeIa.
