ZTF SN Ia DR2: The spectral diversity of Type Ia supernovae in a volume-limited sample

Creators: Burgaz, U. (Corresponding)¹; Maguire, K.¹; Dimitriadis, G.¹; Harvey, L.¹; Senzel, R.¹; Sollerman, J.²; Nordin, J.³; Galbany, L.^{4, 5}; Rigault, M.⁶; Smith, M.⁷; Goobar, A.²; Johansson, J.²; Rosnet, P.⁸; Alburai, A.^{4, 5}; Amenouche, M.⁹; Deckers, M.¹; Dhawan, S.¹⁰; Ginolin, M.⁶; Kim, Y.-L.⁷; Miller, A. A.¹¹; Muller-Bravo, T. E.^{4, 5}; Nugent, P. E.^{12, 13}; Terwel, J. H.¹; Dekany, R.¹⁴; Drake, A.¹⁴; Graham, M. J.¹⁴; Groom, S. L.¹²; Kasliwal, M. M.¹⁴; Kulkarni, S. R.¹⁴; Nolan, K.¹⁴; Nir, G.¹²; Riddle, R. L.¹⁴; Rusholme, B.^{14, 15}; Sharma, Y.¹⁴

1. Trinity College Dublin
2. Stockholm University
3. Humboldt-Universität zu Berlin
4. Institute of Space Sciences
5. Institut d'Estudis Espacials de Catalunya
6. Claude Bernard University Lyon 1
7. Lancaster University
8. University of Clermont Auvergne
9. National Research Council Canada
10. University of Cambridge
11. Northwestern University
12. Lawrence Berkeley National Laboratory
13. University of California, Berkeley
14. California Institute of Technology
15. Infrared Processing and Analysis Center

Abstract

More than 3000 spectroscopically confirmed Type Ia supernovae (SNe Ia) are presented in the second data release (DR2) of the Zwicky Transient Facility survey. In this paper we detail the spectral properties of 482 SNe Ia near maximum light, up to a redshift limit of z ≤ 0.06. We measured the velocities and pseudo-equivalent widths (pEW) of key spectral features (Si IIλ5972 and Si IIλ6355) and investigated the relation between the properties of the spectral features and the photometric properties from the SALT2 light-curve parameters as a function of spectroscopic sub-class. We discuss the non-negligible impact of host galaxy contamination on SN Ia spectral classifications, and we investigate the accuracy of spectral template matching of the DR2 sample. We define a new subclass of underluminous SNe Ia (04gs-like) that lie spectroscopically between normal SNe Ia and transitional 86G-like SNe Ia (stronger Si IIλ5972 than normal SNe Ia, but significantly weaker Ti II features than 86G-like SNe). We model these 04gs-like SN Ia spectra using the radiative-transfer spectral synthesis code TARDIS and show that cooler temperatures alone are unable to explain their spectra; some changes in elemental abundances are also required. However, the broad continuity in spectral properties seen from bright (91T-like) to faint normal SN Ia, including the transitional and 91bg-like SNe Ia, suggests that variations within a single explosion model may be able to explain their behaviour.

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 work was supported by the GROWTH project funded by the National Science Foundation under Grant No 1545949 (Kasliwal et al. 2019). Fritz (van der Walt et al. 2019; Coughlin et al. 2023) is used in this work. The Gordon and Betty Moore Foundation, through both the Data-Driven Investigator Program and a dedicated grant, provided critical funding for SkyPortal. UB, KM, GD, RS, MD, and JHT are supported by the H2020 European Research Council grant no. 758638. LH is funded by the Irish Research Council under grant number GOIPG/2020/1387. Y.-L.K. has received funding from the Science and Technology Facilities Council [grant number ST/V000713/1]. L.G. and T.E.M.B acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN) and the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under 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. L.G acknowledges financial support the Departament de Recerca i Universitats de la Generalitat de Catalunya through the 2021-SGR-01270 grant. T.E.M.B acknowledges financial support from the European Union Next Generation EU/PRTR funds under the 2021 Juan de la Cierva program FJC2021-047124-I. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no 759194 - USNAC). 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. AG acknowledges support from Vetenskapsrådet, the Swedish Research Council, project 2020-03444. SD acknowledges support from the Marie Curie Individual Fellowship under grant ID 890695 and a Junior Research Fellowship at Lucy Cavendish College. This work has been supported by the Agence Nationale de la Recherche of the French government through the program ANR-21-CE31-0016-03.

Data Availability

Full Table A.1 is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/694/A9

Files

aa50386-24.pdf

Files (1.8 MB)

Name	Size	Download all
aa50386-24.pdf md5:6f1af68804973d89fb68a38bb463a7fc	1.8 MB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes