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

March 2025 • 2025ApJ...981L...9P

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

Abstract • 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 (Δm₁₅(B) ∼ 1.25), and applying a fiducial standardization with the BayeSN model we find the SN 2023aeax luminosity distance is in ∼0.1σ 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 ∼1σ distance slope relative to ΛCDM, though in agreement with recent SN Ia cosmological measurements.

Links

• PDF https://iopscience.iop.org/article/10.3847/2041-8213/adb1d9/pdf
• PREPRINT http://arxiv.org/abs/2411.11953
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2025ApJ...981L...9P
• DATA https://doi.org/10.17909/n7kq-ef83
• ELECTR https://iopscience.iop.org/article/10.3847/2041-8213/adb1d9