Aperture-corrected spectroscopic type Ia supernova host galaxy properties

TL;DR

This study examines how aperture effects influence the observed properties of supernova host galaxies and demonstrates that correcting for these effects is crucial for accurate SN-host galaxy relation analysis.

Contribution

It introduces a method to correct for aperture effects in fiber spectroscopy data, improving the accuracy of supernova host galaxy property measurements.

Findings

Aperture corrections alter the observed SN-host galaxy relations.

Discarding poorly covered objects biases the sample and affects results.

Correcting for aperture effects refines the understanding of SN-host correlations.

Abstract

We use type Ia supernovae (SNe Ia) data obtained by the Sloan Digital Sky Survey-II Supernova Survey (SDSS-II/SNe) in combination with the publicly available SDSS DR16 fiber spectroscopy of their host galaxies to correlate SNe Ia light-curve parameters and Hubble residuals to several host galaxy properties. Fixed-aperture fiber spectroscopy suffers from aperture effects: the fraction of the galaxy covered by the fiber varies depending on its projected size on the sky, thus measured properties are not representative of the whole galaxy. The advent of Integral Field Spectroscopy has provided a way for correcting the missing light, by studying how these galaxy parameters change with the aperture size. Here we study how the standard SN host galaxy relations change once global host galaxy parameters are corrected for aperture effects. We recover previous trends on SN Hubble residuals with host galaxy properties, but we find that discarding objects with poor fiber coverage instead of correcting for aperture loss introduces biases in the sample that affect SN host galaxy relations. The net effect of applying the commonly used $g$-band fraction criterion is discarding intrinsically faint \mbox{SNe~Ia} in high-mass galaxies, thus artificially increasing the height of the mass step by 0.02 mag and its significance. Current and next generation of fixed-aperture fiber spectroscopy surveys, such as DES, DESI or TiDES in 4MOST, that aim at study SN and galaxy correlations must consider, and correct for, these effects.