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

Creators: Ginolin, M. (Corresponding)¹; Rigault, M.¹; Copin, Y.¹; Popovic, B.¹; Dimitriadis, G.²; Goobar, A.³; Johansson, J.³; Maguire, K.²; Nordin, J.⁴; Smith, M.⁵; Aubert, M.⁶; Barjou-Delayre, C.⁶; Burgaz, U.²; Carreres, B.^{7, 8}; Dhawan, S.⁹; Deckers, M.²; Feinstein, F.⁷; Fouchez, D.⁷; Galbany, L.^{10, 11}; Ganot, C.¹; de Jaeger, T.¹²; Kim, Y.-L.⁵; Kuhn, D.¹²; Lacroix, L.^{3, 12}; Müller-Bravo, T. E.^{10, 11}; Nugent, P.^{13, 14}; Racine, B.⁷; Rosnet, P.⁶; Rosselli, D.⁷; Ruppin, F.¹; Sollerman, J.³; Terwel, J. H.²; Townsend, A.⁴; Dekany, R.¹⁵; Graham, M.¹⁵; Kasliwal, M.¹⁵; Groom, S. L.^{15, 16}; Purdum, J.¹⁵; Rusholme, B.^{15, 16}; van der Walt, S.¹⁴

1. Claude Bernard University Lyon 1
2. Trinity College Dublin
3. Stockholm University
4. Humboldt-Universität zu Berlin
5. Lancaster University
6. University of Clermont Auvergne
7. Center for Particle Physics of Marseilles
8. Duke University
9. University of Cambridge
10. Institute of Space Sciences
11. Institut d'Estudis Espacials de Catalunya
12. Laboratoire de Physique Nucléaire et de Hautes Énergies
13. Lawrence Berkeley National Laboratory
14. University of California, Berkeley
15. California Institute of Technology
16. Infrared Processing and Analysis Center

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 (4.3σ) 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.

Copyright and License

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Acknowledgement

Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grants No. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. SED Machine is based upon work supported by the National Science Foundation under Grant No. 1106171. The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant #12540303 (PI: Graham). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement n 759194 - USNAC). This work has been supported by the Agence Nationale de la Recherche of the French government through the program ANR-21-CE31-0016-03. This work was supported by the GROWTH project (Kasliwal et al. 2019) funded by the National Science Foundation under Grant No 1545949. TEMB acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN), the Agencia Estatal de Investigación (AEI) 10.13039/501100011033, and the European Union Next Generation EU/PRTR funds under the 2021 Juan de la Cierva program FJC2021-047124-I and the PID2020-115253GA-I00 HOSTFLOWS project, from Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016, and the program Unidad de Excelencia María de Maeztu CEX2020-001058-M. LG acknowledges financial support from AGAUR, CSIC, MCIN and AEI 10.13039/501100011033 under projects PID2020-115253GA-I00, PIE 20215AT016, CEX2020-001058-M, and 2021-SGR-01270. UB, JHT, MD, GD and KM are supported by the H2020 European Research Council grant no. 758638. This work has been supported by the research project grant “Understanding the Dynamic Universe” funded by the Knut and Alice Wallenberg Foundation under Dnr KAW 2018.0067, Vetenskapsrådet, the Swedish Research Council, project 2020-03444. Y.-L.K. has received funding from the Science and Technology Facilities Council [grant number ST/V000713/1]. SD acknowledges support from the Marie Curie Individual Fellowship under grant ID 890695 and a Junior Research Fellowship at Lucy Cavendish College.

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Resource type: Journal Article
Publisher: EDP Sciences
Published in: Astronomy and Astrophysics, 694, A4, ISSN: 0004-6361.
Languages: English