ZTF SN Ia DR2: Evidence of changing dust distribution with redshift using type Ia supernovae

¹ Université Claude Bernard Lyon 1, CNRS, IP2I Lyon/IN2P3, IMR 5822, F-69622 Villeurbanne, France
² Department of Physics, Lancaster University, Lancs LA1 4YB, UK
³ Sorbonne Université, CNRS/IN2P3, LPNHE, F-75005 Paris, France
⁴ The Oskar Klein Centre, Department of Physics, AlbaNova, SE-106 91 Stockholm, Sweden
⁵ School of Physics, Trinity College Dublin, College Green, Dublin 2, Ireland
⁶ National Research Council of Canada, Herzberg Astronomy & Astrophysics Research Centre, 5071 West Saanich Road, Victoria BC V9E 2E7, Canada
⁷ Université Clermont Auvergne, CNRS/IN2P3, LPCA, F-63000 Clermont-Ferrand, France
⁸ Aix Marseille Université, CNRS/IN2P3, CPPM, Marseille, France
⁹ Department of Physics, Duke University Durham, NC 27708, USA
¹⁰ Institute of Astronomy and Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
¹¹ Institute of Space Sciences (ICE-CSIC), Campus UAB, Carrer de Can Magrans, s/n, E-08193 Barcelona, Spain
¹² Institut d’Estudis Espacials de Catalunya (IEEC), 08860 Castelldefels (Barcelona), Spain
¹³ Division of Physics, Mathematics & Astronomy, California Institute of Technology, Pasadena, CA 91125, USA
¹⁴ The Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden
¹⁵ Nordic Optical Telescope, Rambla José Ana Fernández Pérez 7, ES-38711 Breña Baja, Spain
¹⁶ Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50B-4206, Berkeley CA 94720, USA
¹⁷ Department of Astronomy, University of California, Berkeley, 501 Campbell Hall, Berkeley CA 94720, USA

^⋆ Corresponding author; b.popovic@ip2i.in2p3.fr

Received: 15 April 2024
Accepted: 1 August 2024

Abstract

Context. Type Ia supernova (SNIa) are excellent probes of local distance and the growing sample sizes of SNIa have driven an increased propensity to study the associated systematic uncertainties and improve standardisation methods in preparation for the next generation of cosmological surveys into the dark energy equation of state, w.

Aims. We aim to probe the potential change in the SNIa standardisation parameter, c, with redshift and the host-galaxy of the supernova. Improving the standardisation of SNIa brightness measurements will require the relationship between the host and the SNIa to be accounted for. In addition, potential shifts in the SNIa standardisation parameters with redshift will cause biases in the recovered cosmology.

Methods. In this work, we assembled a volume-limited sample of 3000 likely SNIa across a redshift range from z = 0.015 to z = 0.36. This sample was fitted with changing mass and redshift bins to determine the relationship between the intrinsic properties of SNe Ia and their redshift and host galaxy parameters. We then investigated the colour-luminosity parameter, β, as a subsequent test of the SNIa standardisation process.

Results. We find that the changing colour distribution of SNe Ia with redshift is driven by dust at a confidence of > 4σ. Additionally, we show a strong correlation between the host galaxy mass and the colour-luminosity coefficient β (> 4σ), even when accounting for the quantity of dust in a host galaxy.

Conclusions. These results indicate that the observed colour distribution of SNe Ia does change with redshift. However, we note that this is an observational effect, rather than an intrinsic change. Future cosmological measurements with SNe Ia must take into account these changing dust distributions to reduce the number of potential sources of systematic uncertainty.