Near-IR Type Ia SN distances: host galaxy extinction and mass-step
  corrections revisited
  We present optical and near-infrared (NIR, $YJH$-band) observations of 42
Type Ia supernovae (SNe Ia) discovered by the untargeted intermediate Palomar
Transient Factory (iPTF) survey. This new data-set covers a broad range of
redshifts and host galaxy stellar masses, compared to previous SN Ia efforts in
the NIR. We construct a sample, using also literature data at optical and NIR
wavelengths, to examine claimed correlations between the host stellar masses
and the Hubble diagram residuals. The SN magnitudes are corrected for host
galaxy extinction using either a global total-to-selective extinction ratio,
$R_V$=2.0 for all SNe, or a best-fit $R_V$ for each SN individually. Unlike
previous studies which were based on a narrower range in host stellar mass, we
do not find evidence for a "mass-step", between the color- and
stretch-corrected peak $J$ and $H$ magnitudes for galaxies below and above
$\log(M_{*}/M_{\odot}) = 10$. However, the mass-step remains significant
($3\sigma$) at optical wavelengths ($g,r,i$) when using a global $R_V$, but
vanishes when each SN is corrected using their individual best-fit $R_V$. Our
study confirms the benefits of the NIR SN Ia distance estimates, as these are
largely exempted from the empirical corrections dominating the systematic
uncertainties in the optical.
