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Arxiv: Testing for Intrinsic Type Ia Supernova Luminosity Evolution at z>2 with JWST Published: 11/18/2024 9:00:01 PM Updated: 11/18/2024 9:00:01 PM

Paper abstract: The James Webb Space Telescope (JWST) is opening new frontiers of transientdiscovery and follow-up at high-redshift. Here we present the discovery of aspectroscopically confirmed Type Ia supernova (SN Ia; SN 2023aeax) at z=2.15with JWST, with cadenced NIRCam observations that enable multi-band light curvefitting. SN 2023aeax lands at the edge of traditional low-z cosmology colorcuts because of its blue color (peak rest-frame B-V~-0.3), but we still apply afiducial standardization approach with the BayeSN model and find that the SN2023aeax luminosity distance measurement is in agreement (~0.1sigma) withLambdaCDM. SN 2023aeax is only the second spectroscopically confirmed SN Ia inthe dark matter-dominated Universe at z>2 (the other is SN 2023adsy), giving itrare leverage to constrain any potential evolution in SN Ia standardizedluminosities. Similar to SN 2023adsy (B-V~0.8), SN 2023aeax has a fairlyextreme (but opposite) color, which may be due to the small sample size or asecondary factor, such as host galaxy properties. Nevertheless, the SN 2023aeaxspectrum is well-represented by normal low-z SN Ia spectra and we find nodefinitive evolution in SN Ia standardization with redshift. Still, the firsttwo spectroscopically confirmed z>2 SNe Ia have peculiar colors and combine fora ~1sigma distance slope relative to LambdaCDM, the implications of whichrequire a larger sample and dedicated host galaxy observations to investigate.