ZTF SN Ia DR2: Colour standardisation of type Ia supernovae and its dependence on the environment

Context. As type Ia supernova cosmology transitions from a statistics-dominated to a systematics-dominated era, it is crucial to understand the remaining unexplained uncertainties that affect their luminosity, such as those stemming from astrophysical biases. Type Ia supernovae are standardisable candles whose absolute magnitude reaches a scatter of typically 0.15 mag when empirical correlations with their light-curve stretch and colour and with their environmental properties are accounted for. Aims. We investigate the dependence of the standardisation process of type Ia supernovae on the astrophysical environment to ultimately reduce their scatter in magnitude. We focus on colour standardisation. Methods. We used the volume-limited ZTF SN Ia DR2 sample, which offers unprecedented statistics for the low-redshift ( z < 0.06) range. We first studied the colour distribution with a focus on the effects of dust to then select a dustless subsample of objects that originated in environments with a low stellar mass and in the outskirts of their host galaxies. We then examined the colour-residual relation and its associated parameter β . Finally, we investigated the colour dependence of the environment-dependent magnitude offsets (steps) to separate their intrinsic and extrinsic components. Results. Our sample of nearly 1000 supernovae probes the red tail of the colour distribution up to c = 0.8. The dustless sample exhibits a significantly shorter red tail (4.3 σ ) than the whole sample, but the distributions around c ∼ 0 are similar for both samples. This suggests that the reddening above c ≥ 0.2 is dominated by interstellar dust absorption of the host and that the remaining colour scatter has an intrinsic origin. The colour-residual relation is linear with light-curve colour. We found indications of a potential evolution of β with the stellar host mass, with β ∼ 3.6 for low-mass galaxies, compared to β = 3.05 ± 0.06 for the full sample. Finally, in contrast to recent claims from the literature, we found no evolution of steps as a function of light-curve colour. This suggests that dust may not be the dominating mechanism for the dependence on the environment of the magnitude of type Ia supernovae.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-02-01
DOI
https://doi.org/10.1051/0004-6361/202450943
Citations
18
Primary Topic
Gamma-ray bursts and supernovae
Type
article
Field-Weighted Citation Impact
17.32

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article

ZTF SN Ia DR2: Colour standardisation of type Ia supernovae and its dependence on the environment

K. Maguire, J. Terwel, G. Dimitriadis, F. Ruppin et al.
18 citations
Astronomy and Astrophysics
Gamma-ray bursts and supernovae
17.32
article

ZTF SN Ia DR2: Colour standardisation of type Ia supernovae and its dependence on the environment

K. Maguire, J. Terwel, G. Dimitriadis, F. Ruppin, L. Galbany, M Ginolin, Young-Lo Kim, M. R. Smith, J. Nordin, Y. Copin, T. E. Müller-Bravo, M Aubert, A. Goobar, F. Feinstein, Suhail Dhawan, Alice Townsend, J. Sollerman, Richard Dekany, P. Rosnet, M. J. Graham, M. Rigault, D. Fouchez, Josiah Purdum, Thomas de Jaeger, Leander Lacroix, Stéfan van der Walt, P. Nugent, Steven L. Groom, Bastien Carreres, J. Johansson, B. Rusholme, B Popovic, U. Burgaz, M. Deckers, C Barjou-Delayre, C Ganot, M. M. Kasliwal, B. Racine, Daisy A. Kuhn, D. Rosselli
article en
18 citations

Abstract

Context. As type Ia supernova cosmology transitions from a statistics-dominated to a systematics-dominated era, it is crucial to understand the remaining unexplained uncertainties that affect their luminosity, such as those stemming from astrophysical biases. Type Ia supernovae are standardisable candles whose absolute magnitude reaches a scatter of typically 0.15 mag when empirical correlations with their light-curve stretch and colour and with their environmental properties are accounted for. Aims. We investigate the dependence of the standardisation process of type Ia supernovae on the astrophysical environment to ultimately reduce their scatter in magnitude. We focus on colour standardisation. Methods. We used the volume-limited ZTF SN Ia DR2 sample, which offers unprecedented statistics for the low-redshift ( z < 0.06) range. We first studied the colour distribution with a focus on the effects of dust to then select a dustless subsample of objects that originated in environments with a low stellar mass and in the outskirts of their host galaxies. We then examined the colour-residual relation and its associated parameter β . Finally, we investigated the colour dependence of the environment-dependent magnitude offsets (steps) to separate their intrinsic and extrinsic components. Results. Our sample of nearly 1000 supernovae probes the red tail of the colour distribution up to c = 0.8. The dustless sample exhibits a significantly shorter red tail (4.3 σ ) than the whole sample, but the distributions around c ∼ 0 are similar for both samples. This suggests that the reddening above c ≥ 0.2 is dominated by interstellar dust absorption of the host and that the remaining colour scatter has an intrinsic origin. The colour-residual relation is linear with light-curve colour. We found indications of a potential evolution of β with the stellar host mass, with β ∼ 3.6 for low-mass galaxies, compared to β = 3.05 ± 0.06 for the full sample. Finally, in contrast to recent claims from the literature, we found no evolution of steps as a function of light-curve colour. This suggests that dust may not be the dominating mechanism for the dependence on the environment of the magnitude of type Ia supernovae.

Astronomy and AstrophysicsVol. 694
Université Claude Bernard Lyon 1 (FR), California Institute of Technology (US), Centre National de la Recherche Scientifique (FR), Institute of Space Sciences (ES), Lawrence Berkeley National Laboratory (US), Stockholm University (SE), Duke University (US), Lyon College (US), Université Clermont Auvergne (FR), Trinity College Dublin (IE), Aix-Marseille Université (FR), University of Cambridge (GB), Humboldt-Universität zu Berlin (DE), Sorbonne Université (FR), Institut d'Estudis Espacials de Catalunya (ES), Laboratoire de Physique Nucléaire et de Hautes Énergies (FR), Nordic Optical Telescope (ES), Infrared Processing and Analysis Center (US), Université Paris 1 Panthéon-Sorbonne (FR), Lancaster University (GB), University of California, Berkeley (US)
National Science Foundation, California Institute of Technology, Northwestern University, University of Washington, University of Warwick, European Commission, Trinity College Dublin, Agence Nationale de la Recherche, Weizmann Institute of Science, Knut och Alice Wallenbergs Stiftelse, Vetenskapsrådet, Ministerio de Ciencia e Innovación, Stockholms Universitet, Horizon 2020 Framework Programme, Science and Technology Facilities Council, Deutsches Elektronen-Synchrotron, Agència de Gestió d'Ajuts Universitaris i de Recerca, Agencia Estatal de Investigación, Institut National de Physique Nucléaire et de Physique des Particules, H2020 European Research Council, HORIZON EUROPE European Research Council
Openalex Percentile: Top 1%
Gamma-ray bursts and supernovae
17.32
DOIOpen Access PDFOpenAlex
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