Effects of stellar rotation on star formation rates and comparison to
  core-collapse supernova rates
  We investigate star formation rate (SFR) calibrations in light of recent
developments in the modeling of stellar rotation. Using new published
non-rotating and rotating stellar tracks, we study the integrated properties of
synthetic stellar populations and find that the UV to SFR calibration for the
rotating stellar population is 30% smaller than for the non-rotating stellar
population, and 40% smaller for the Halpha to SFR calibration. These reductions
translate to smaller SFR estimates made from observed UV and Halpha
luminosities. Using the UV and Halpha fluxes of a sample of ~300 local
galaxies, we derive a total (i.e., sky-coverage corrected) SFR within 11 Mpc of
120-170 Msun/yr and 80-130 Msun/yr for the non-rotating and rotating
estimators, respectively. Independently, the number of core-collapse supernovae
discovered in the same volume requires a total SFR of 270^{+110}_{-80} Msun/yr,
suggesting a mild tension with the SFR estimates made with rotating
calibrations. More generally, when compared with the estimated SFR, the local
supernova discoveries strongly constrain any physical effects that might
increase the energy output of massive stars, including, but not limited to,
stellar rotation. The cosmic SFR and cosmic supernova rate data on the other
hand show the opposite trend, with the cosmic SFR almost double that inferred
from cosmic supernovae, constraining a significant decrease in the energy
output of massive stars. Together, these lines of evidence suggest that the
true SFR calibration factors cannot be too far from their canonical values.
