The Astrophysical Journal Letters (Jan 2025)

Testing for Intrinsic Type Ia Supernova Luminosity Evolution at z > 2 with JWST

  • J. D. R. Pierel,
  • D. A. Coulter,
  • M. R. Siebert,
  • H. B. Akins,
  • M. Engesser,
  • O. D. Fox,
  • M. Franco,
  • A. Rest,
  • A. Agrawal,
  • Y. Ajay,
  • N. Allen,
  • C. M. Casey,
  • C. DeCoursey,
  • N. E. Drakos,
  • E. Egami,
  • A. L. Faisst,
  • S. Gezari,
  • G. Gozaliasl,
  • O. Ilbert,
  • D. O. Jones,
  • M. Karmen,
  • J. S. Kartaltepe,
  • A. M. Koekemoer,
  • Z. G. Lane,
  • R. L. Larson,
  • T. Li,
  • D. Liu,
  • T. J. Moriya,
  • H. J. McCracken,
  • L. Paquereau,
  • R. M. Quimby,
  • R. M. Rich,
  • J. Rhodes,
  • B. E. Robertson,
  • D. B. Sanders,
  • M. Shahbandeh,
  • M. Shuntov,
  • J. D. Silverman,
  • L. G. Strolger,
  • S. Toft,
  • Y. Zenati

DOI
https://doi.org/10.3847/2041-8213/adb1d9
Journal volume & issue
Vol. 981, no. 1
p. L9

Abstract

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The James Webb Space Telescope (JWST) is opening new frontiers of transient discovery and follow-up at high redshift. Here we present the discovery of a spectroscopically confirmed Type Ia supernova (SN Ia; SN 2023aeax) at z = 2.15 with JWST, including a NIRCam multiband light curve. SN 2023aeax lands at the edge of traditional low- z cosmology cuts because of its blue color (peak rest-frame B − V ∼ −0.3) but with a normal decline rate (Δ m _15 ( B ) ∼ 1.25), and applying a fiducial standardization with the BayeSN model we find the SN 2023aeax luminosity distance is in ∼0.1 σ agreement with ΛCDM. SN 2023aeax is only the second spectroscopically confirmed SN Ia in the dark matter–dominated Universe at z > 2 (the other is SN 2023adsy), giving it rare leverage to constrain any potential evolution in SN Ia standardized luminosities. Similar to SN 2023adsy ( B − V ∼ 0.8), SN 2023aeax has a fairly extreme (but opposite) color, which may be due to the small sample size or a secondary factor, such as host galaxy properties. Nevertheless, the SN 2023aeax spectrum is well represented by normal low- z SN Ia spectra, and we find no definitive evolution in SN Ia standardization with redshift. Still, the first two spectroscopically confirmed z > 2 SNe Ia have peculiar colors and combine for a ∼1 σ distance slope relative to ΛCDM, though in agreement with recent SN Ia cosmological measurements.

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