Keck Observations of the Young Metal-Poor Host Galaxy of the
  Super-Chandrasekhar-Mass Type Ia Supernova SN 2007if
  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
$m_g=23.15\pm0.06$, which at the spectroscopically-measured redshift of
$z_{helio}=0.07450\pm0.00015$ corresponds to an absolute magnitude of
$M_g=-14.45\pm0.06$. Galaxy $g-r$ color constrains the mass-to-light ratio,
giving a host stellar mass estimate of $\log(M_*/M_\odot)=7.32\pm0.17$. Balmer
absorption in the stellar continuum, along with the strength of the 4000\AA\
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 $12+\log(O/H)_\mathrm{KK04}=8.01\pm0.09$,
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.
