We present Keck LRIS spectroscopy and g -band photometry of the metal-poor , low-luminosity host galaxy of the super-Chandrasekhar mass Type Ia supernova SN 2007if .
Deep imaging of the host reveals its apparent magnitude to be m _ { g } = 23.15 \pm 0.06 , which at the spectroscopically-measured redshift of z _ { helio } = 0.07450 \pm 0.00015 corresponds to an absolute magnitude of M _ { g } = -14.45 \pm 0.06 .
Galaxy g - r color constrains the mass-to-light ratio , giving a host stellar mass estimate of \log ( M _ { * } / M _ { \odot } ) = 7.32 \pm 0.17 .
Balmer absorption in the stellar continuum , along with the strength of the 4000Å break , constrain the age of the dominant starburst in the galaxy to be t _ { \mathrm { burst } } = 123 ^ { +165 } _ { -77 } Myr , corresponding to a main-sequence turn-off mass of M / M _ { \odot } = 4.6 ^ { +2.6 } _ { -1.4 } .
Using the R _ { 23 } method of calculating metallicity from the fluxes of strong emission lines , we determine the host oxygen abundance to be 12 + \log ( O / H ) _ { \mathrm { KK 04 } } = 8.01 \pm 0.09 , significantly lower than any previously reported spectroscopically-measured Type Ia supernova host galaxy metallicity .
Our data show that SN 2007if is very likely to have originated from a young , metal-poor progenitor .