Published February 2025 | Published
Journal Article Open

ZTF SN Ia DR2: Peculiar velocities' impact on the Hubble diagram

  • 1. ROR icon Center for Particle Physics of Marseilles
  • 2. ROR icon Duke University
  • 3. ROR icon University of Clermont Auvergne
  • 4. ROR icon Trinity College Dublin
  • 5. ROR icon Stockholm University
  • 6. ROR icon Humboldt-Universität zu Berlin
  • 7. ROR icon Claude Bernard University Lyon 1
  • 8. ROR icon Lancaster University
  • 9. ROR icon National Research Council Canada
  • 10. ROR icon Laboratoire de Physique Nucléaire et de Hautes Énergies
  • 11. ROR icon University of Cambridge
  • 12. ROR icon Institute of Space Sciences
  • 13. ROR icon Deutsches Elektronen-Synchrotron DESY
  • 14. ROR icon Lawrence Berkeley National Laboratory
  • 15. ROR icon University of California, Berkeley
  • 16. ROR icon California Institute of Technology
  • 17. ROR icon Infrared Processing and Analysis Center
  • 18. ROR icon Drexel University

Abstract

Type Ia supernovae (SNe Ia) are used to determine the distance-redshift relation and build the Hubble diagram. Neglecting their host-galaxy peculiar velocities (PVs) may bias the measurement of cosmological parameters. The smaller the redshift, the larger the effect is. We used realistic simulations of SNe Ia observed by the Zwicky Transient Facility (ZTF) to investigate the effect of different methods of taking PVs into account. We studied the impact of neglecting galaxy PVs and their correlations in an analysis of the SNe Ia Hubble diagram. We find that it is necessary to use the PV full covariance matrix computed from the velocity power spectrum to take the sample variance into account. Considering the results we have obtained using simulations, we determine the PV systematic effects in the context of the ZTF SN Ia DR2 sample. We determine the PV impact on the intercept of the Hubble diagram, aB, which is directly linked to the measurement of H0. We show that not taking into account PVs and their correlations results in a shift in the H0 value of about 1.0 km s−1 Mpc−1 and a slight underestimation of the H0 error bar.

Copyright and License

© The Authors 2025.

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 project leading to this publication has received funding from Excellence Initiative of Aix-Marseille University – A*MIDEX, a French “Investissements d’Avenir” program (AMX-20-CE-02 – DARKUNI). This work has been carried out thanks to the support of the DEEPDIP ANR project (ANR-19-CE31-0023). This work received support from the French government under the France 2030 investment plan, as part of the Initiative d’Excellence d’Aix-Marseille Université – A*MIDEX (AMX-19-IET-008 – IPhU). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement n°759194 – USNAC). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (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 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 and the G.R.E.A.T. research environment, project number 2016-06012. L.G. 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, and from the Departament de Recerca i Universitats de la Generalitat de Catalunya through the 2021-SGR-01270 grant. G.D. is supported by the H2020 European Research Council grant no. 758638. T.E.M.B. 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. U.B. and J.H.T. are supported by the H2020 European Research Council grant no. 758638.

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Additional details

Created:
February 19, 2025
Modified:
February 19, 2025