Expanding the High-z Supernova Frontier: "Wide-Area" JWST Discoveries from the First Two Years of COSMOS-Web

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Authors: Ori Dosovitz Fox, A. Rest, Justin D. R. Pierel, David A. Coulter, Caitlin M. Casey, Jeyhan S. Kartaltepe, Hollis B. Akins, Maximilien Franco, Michael Engesser, Conor Larison, Takashi J. Moriya, R. Quimby
+39 more Marko Shuntov, Matthew R. Siebert, Christa DeCoursey, Rodrigo Angulo, James M. DerKacy, Nicole E. Drakos, Eiichi Egami, Steven L. Finkelstein, Carter Flayhart, Seiji Fujimoto, Estefania Padilla Gonzalez, M. Griggio, Santosh Harish, Olivier Ilbert, Kohei Inayoshi, Anton M. Koekemoer, Vasily Kokorev, C. Laigle, Erini Lambrides, Rebecca L. Larson, Xiaolong Li, Daizhong Liu, G. Magdis, Jacqueline McCleary, Henry Joy McCracken, Nicolas McMahon, Jed McKinney, Thomas Moore, Louise Paquereau, Jason Rhodes, Brant E. Robertson, David B. Sanders, Sogol Sanjaripour, Koji Shukawa, Louis-Gregory Strolger, Sune Toft, Qinan Wang, Robert Edward Williams, Yossef Zenati
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Abstract

Transient astronomy in the early Universe (z > 2) remains largely unexplored, lying beyond the rest-frame optical spectroscopic reach of most current observatories. Yet this regime promises transformative insights, with high-redshift transients providing direct access to the early Universe and enabling studies of how stellar populations and cosmology evolve over cosmic time. JWST is uniquely equipped to probe these redshifts efficiently in the rest-frame optical and near-IR. We present results from an initial pathfinder search, covering an area of ~133 arcmin^2 (~0.037 deg^2) independently imaged by the PRIMER and COSMOS-Web (hereafter COSMOS) extragalactic surveys. Although neither program was designed for time-domain astronomy, combining their data results in difference images separated by roughly one year, leading to the discovery of 68 supernovae (SNe) with host photometric redshifts reaching z < 5. For most SNe, only a single epoch is available, but the combination of host redshift, classification, color, and magnitude enables us to prioritize candidates for detailed photometric and spectroscopic follow-up. Among the most notable sources are a relatively bright, blue CCSN at z > 3 (SN 2023aeab) and a young, normal SN Ia at z > 2 (SN 2023aeax). The sample distribution highlights the increasing likelihood that a wide-area JWST program can uncover younger, bluer, and potentially more extreme explosions. While this pathfinder effort is limited in cadence and number of filters, it demonstrates the strong potential of a dedicated, well-planned time-domain survey with JWST to obtain the sample sizes and rate measurements needed to chart SN populations deep into the early Universe.

Fields of Study & Subjects

Gamma-ray bursts and supernovae Galaxies: Formation Evolution Phenomena Astrophysics and Cosmic Phenomena

Publication details

Journal / source
arXiv (Cornell University)
Publication date
13 January 2026
Document type
Preprint