ZTF SN Ia DR2: Exploring SN Ia properties in the vicinity of under-dense environments

¹ Université Clermont Auvergne, CNRS/IN2P3, LPCA, F-63000 Clermont-Ferrand, France
² Univ Lyon, Univ Claude Bernard Lyon 1, CNRS, IP2I Lyon/IN2P3, UMR 5822, F-69622 Villeurbanne, France
³ Department of Physics, Lancaster University, Lancs LA1 4YB, UK
⁴ School of Physics, Trinity College Dublin, College Green, Dublin 2, Ireland
⁵ The Oskar Klein Centre, Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
⁶ Aix Marseille Université, CNRS/IN2P3, CPPM, Marseille, France
⁷ Department of Physics, Duke University, Durham, NC 27708, USA
⁸ Institute of Space Sciences (ICE-CSIC), Campus UAB, Carrer de Can Magrans, s/n, E-08193 Barcelona, Spain
⁹ Institut d’Estudis Espacials de Catalunya (IEEC), 08860 Castelldefels (Barcelona), Spain
¹⁰ LPNHE, CNRS/IN2P3, Sorbonne Université, Université Paris-Cité, Laboratoire de Physique Nucléaire et de Hautes Énergies, 75005 Paris, France
¹¹ Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA
¹² IPAC, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, USA
¹³ Caltech Optical Observatories, California Institute of Technology, Pasadena, CA 91125, USA
¹⁴ Department of Astronomy, The Oskar Klein Center, Stockholm University, AlbaNova, 10691 Stockholm, Sweden
¹⁵ Nordic Optical Telescope, Rambla José Ana Fernández Pérez 7, ES-38711 Breña Baja, Spain
¹⁶ Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany

^⋆ Corresponding author; marie.aubert@clermont.in2p3.fr

Received: 31 May 2024
Accepted: 3 September 2024

Abstract

Context. The unprecedented statistics of detected Type Ia supernovae (SNe Ia) brought by the Zwicky Transient Facility (ZTF) enable us to probe the impact of the large-scale structure (LSS) on the properties of these objects.

Aims. The goal of this paper is to explore the possible impact of the under-dense part of the LSS on the intrinsic SALT2 light-curve properties of SNe Ia and uncover possible biases in SN Ia analyses.

Methods. With a volume-limited selection of ZTF-Cosmo-DR2 SNe Ia overlapping with the SDSS-DR7 survey footprint, we investigated the distribution of their properties with regard to voids detected in the SDSS-DR7 galaxy sample. We further used Voronoi volumes as a proxy for local density environments within the LSS.

Results. We find a moderate dependency of the stretch on the localisation around the void centre and none when considering colour. The local Voronoi volumes mostly affect the fraction of low- and high-stretch supernovae.

Conclusions. With the presently available statistics, we consider that the impact of high- or low-local-density environment can be considered as a proxy for the colour of the host galaxy. Under-dense environments should not cause any biases in analyses of supernova.