Testing for Intrinsic Type Ia Supernova Luminosity Evolution at z > 2 with JWST
Justin Pierel, D. A. Coulter, M. R. Siebert, Hollis B. Akins, Michael Engesser, Ori D. Fox, Maximilien Franco, A. Rest, Abhishek Agrawal, Yukta Ajay, Natalie Allen, Caitlin M. Casey, Christa DeCoursey, Nicole E. Drakos, Eiichi Egami, Andreas L. Faisst, Suvi Gezari, G. Gozaliasl, O. Ilbert, D. O. Jones, Mitchell Karmen, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Zachary G. Lane, Rebecca L. Larson, Tian Li, Daizhong Liu, Takashi J. Moriya, H. J. McCracken, Louise Paquereau, R. Quimby, R. Michael Rich, Jason Rhodes, Brant Robertson, D. B. Sanders, Melissa Shahbandeh, Marko Shuntov, J. D. Silverman, Louis-Gregory Strolger, Sune Toft, Yossef Zenati
Abstract
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 (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.