The Dependence of the Type Ia Supernova Host Bias on Observation or Fitting Technique
2022
ASTROPHYSICAL JOURNAL
DOI
10.3847/1538-4357/ac389f
More luminous Type Ia supernovae prefer less massive hosts and regions of higher star formation. This correlation is inverted during width-color-luminosity light-curve standardization resulting in step-like biases of distance measurements with respect to host properties. Using the PMAS/PPak Integral-field Supernovahosts COmpilation (PISCO) supernova host sample and Sloan Digital Sky Survey, Galaxy Evolution Explorer, and Two Micron All Sky Survey photometry, we compare host stellar mass and specific star-formation rate (sSFR) from different observation methods, including local versus global, and fitting techniques to measure their impact on the host step biases. Mass-step measurements for all our mass samples are consistent within a 1 sigma significance from -0.03 +/- 0.02 mag to -0.04 +/- 0.02 mag. Including or excluding UV information had no effect on measured mass-step size or location. sSFR step sizes are more significant than mass-step measurements and varied from 0.05 +/- 0.03 mag (H alpha) and 0.06 +/- 0.02 mag (UV) for a 51 host sample. The sSFR step location is influenced by the mass sample used to normalize star formation and by sSFR tracer choice. The step size is reduced to 0.04 +/- 0.03 mag when using all available 73 hosts with H alpha measurements. This 73 PISCO host subsample overall lacked a clear step signal, but here we are searching for whether different choices of mass or sSFR estimation can create a step signal. We find no evidence that different observation or fitting techniques choices can create a distance measurement step in either mass or sSFR.