Near-IR Type Ia SN distances: host galaxy extinction and mass-step corrections revisited

TL;DR

This study analyzes optical and near-infrared observations of 42 Type Ia supernovae to investigate host galaxy effects on distance measurements, finding that NIR distances are less affected by host galaxy properties and extinction corrections.

Contribution

It provides new NIR data for a broad range of host galaxy masses and demonstrates that NIR SN Ia distances are less sensitive to host galaxy mass-step effects compared to optical wavelengths.

Findings

No evidence for a host mass-step in NIR magnitudes after individual extinction correction.

Mass-step remains significant in optical wavelengths with a global R_V but disappears with individual R_V corrections.

NIR SN Ia distances are less affected by host galaxy properties and systematic uncertainties.

Abstract

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.