Discovery of an Apparent Red, High-velocity Type Ia Supernova at z = 2.9 with JWST
Maiolino, R.; Fox, O. D.; Rest, A.; Sun, F.; Egami, E.; Johnson, B. D.; Wevers, T.; Eisenstein, D. J.; Shahbandeh, M.; Bunker, A. J.; Moriya, T. J.; Curti, M.; Jones, D. O.; Chen, W.; Robertson, B.; Pierel, J. D. R.; Cargile, P. A.; Gezari, S.; Coulter, D. A.; Siebert, M. R.; Quimby, R. M.; Zenati, Y.; Joshi, B. A.; Engesser, M.; Gomez, S.; Strolger, L. G.; DeCoursey, C.; Guolo, M.; Wang, Q.; Karmen, M.
United States, Japan, Australia, United Kingdom, Germany
Abstract
We present the James Webb Space Telescope (JWST) discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS+53.13485‑27.82088 with a host spectroscopic redshift of 2.903 ± 0.007. The transient was identified in deep (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic follow-up with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (c ∼ 0.9) despite a host galaxy with low extinction and has a high Ca II velocity (19,000 ± 2000 km s‑1) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-z Ca-rich population. Although such an object is too red for any low-z cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (≲1σ) with ΛCDM. Therefore unlike low-z Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high z truly diverge from their low-z counterparts and to confirm that standardized luminosities nevertheless remain constant with redshift.