Discovery of an Apparent Red, High-velocity Type Ia Supernova at z = 2.9 with JWST
Justin Pierel, Michael Engesser, D. A. Coulter, Christa DeCoursey, M. R. Siebert, A. Rest, Eiichi Egami, Wenlei Chen, Ori D. Fox, D. O. Jones, Bhavin Joshi, Takashi J. Moriya, Yossef Zenati, Andrew J. Bunker, Phillip A. Cargile, Mirko Curti, Daniel J. Eisenstein, Suvi Gezari, Sebastián Gómez, Muryel Guolo, Benjamin D. Johnson, Mitchell Karmen, R. Maiolino, R. Quimby, Brant Robertson, Melissa Shahbandeh, Louis-Gregory Strolger, Fengwu Sun, Qinan Wang, T. Wevers
Abstract
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 (≲1 σ ) 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.