Aperture-corrected spectroscopic type Ia supernova host galaxy properties^⋆

¹ Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
e-mail: lgalbany@ice.csic.es
² Institut d’Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain
³ Univ. Lyon, Univ. Claude Bernard Lyon 1, CNRS, IP2I Lyon/IN2P3, IMR 5822, 69622 Villeurbanne, France
⁴ Département de Physique, de Génie Physique et d’Optique, Université Laval, and Centre de Recherche en Astrophysique du Québec (CRAQ), Québec, QC G1V 0A6, Canada
⁵ Instituto de Astrofísica de Andalucía – CSIC, Glorieta de la Astronomía s.n., 18008 Granada, Spain
⁶ CENTRA/COSTAR, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
⁷ Max-Planck-Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁸ Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
⁹ Australian Astronomical Optics, Macquarie University, 105 Delhi Rd, North Ryde, NSW 2113, Australia
¹⁰ Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109, Australia
¹¹ Macquarie University Research Centre for Astronomy, Astrophysics & Astrophotonics, Sydney, NSW 2109, Australia
¹² ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO-3D), Sydney, Australia
¹³ Dpto. de Investigación Básica, CIEMAT, Avda. Complutense 40, 28040 Madrid, Spain

Received: 14 June 2021
Accepted: 4 December 2021

Abstract

We use type Ia supernova (SN Ia) data obtained by the Sloan Digital Sky Survey-II Supernova Survey (SDSS-II SNS) in combination with the publicly available SDSS DR16 fiber spectroscopy of supernova (SN) host galaxies to correlate SN Ia light-curve parameters and Hubble residuals with 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, and thus measured properties are not representative of the whole galaxy. The advent of integral field spectroscopy has provided a way to correct 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 into the sample that affect SN host galaxy relations. The net effect of applying the commonly used g-band fraction criterion is that intrinsically faint SNe Ia in high-mass galaxies are discarded, thus artificially increasing the height of the mass step by 0.02 mag and its significance. Current and next-generation fixed-aperture fiber-spectroscopy surveys, such as OzDES, DESI, or TiDES with 4MOST, that aim to study SN and galaxy correlations must consider, and correct for, these effects.