A1 Refereed original research article in a scientific journal
The First Photometric Evidence of a Transient/Variable Source at z > 5 with JWST
Authors: DeCoursey, Christa; Egami, Eiichi; Sun, Fengwu; Akhtarkavan, Arshia; Bhatawdekar, Rachana; Bunker, Andrew J.; Coulter, David A.; Engesser, Michael; Fox, Ori D.; Gomez, Sebastian; Inayoshi, Kohei; Johnson, Benjamin D.; Karmen, Mitchell; Larison, Conor; Lin, Xiaojing; Lyu, Jianwei; Mattila, Seppo; Moriya, Takashi J.; Pierel, Justin D. R.; Puskás, Dávid; Rest, Armin; Rieke, George H.; Robertson, Brant; Salamat, Sepehr; Strolger, Louis-Gregory; Tacchella, Sandro; Vassallo, Christian; Williams, Christina C.; Zenati, Yossef; Zhang, Junyu
Publisher: Institute of Physics Publishing
Publication year: 2025
Journal:: Astrophysical Journal
Article number: 31
Volume: 990
Issue: 1
ISSN: 0004-637X
eISSN: 1538-4357
DOI: https://doi.org/10.3847/1538-4357/ade78c
Web address : https://doi.org/10.3847/1538-4357/ade78c
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/500330975
The James Webb Space Telescope (JWST) discovered 79 transients out to z ∼ 4.8 through the JADES Transient Survey (JTS), but the JTS did not find any z > 5 transients. We present the first photometric evidence of a z > 5 transient/variable source with JWST. The source, AT 2023adya, resides in a zspec = 5.274 galaxy in GOODS-N, which dimmed from mF356W = 26.05 ± 0.02 mag to 26.24 ± 0.02 mag in the rest-frame optical over approximately 2 rest-frame months, producing a clear residual signal in the difference image (mF356W = 28.01 ± 0.17 mag; SNvar = 6.09) at the galaxy center. Shorter-wavelength bands (F090W/F115W) show no rest-frame UV brightness change. Based on its rest-frame V-band absolute magnitude (MV = −18.48 mag), AT 2023adya could be any core-collapse supernova (SN) subtype or an SN Ia. However, due to low SN Ia rates at high redshift, the SN Ia scenario is unlikely. Alternatively, AT 2023adya may be a variable active galactic nucleus (AGN). The NIRCam/Grism spectrum shows no broad Hα emission line (FWHM = 130 ± 26 km s−1), but we cannot exclude the existence of a faint broad line and therefore cannot exclude the AGN scenario. AT 2023adya is unlikely to be a tidal disruption event (TDE) because the TDE models matching the observed brightness changes have low event rates. Although it is not possible to determine AT 2023adya’s nature based on the two-epoch single-band photometry alone, this discovery pushes the transient/variable science frontier past z = 5 and toward the Epoch of Reionization.
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Funding information in the publication:
Support for program #3577 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. The authors acknowledge the FRESCO team for developing their observing program with a zero-exclusive-access period.
A.J.B. acknowledges funding from the “FirstGalaxies” Advanced Grant from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 789056). K.I. acknowledges support from National Natural Science Foundation of China (grant Nos. 12073003, 12003003, 11721303, 11991052, and 11950410493) and the China Manned Space Project (CMS-CSST-2021-A04 and CMS-CSST-2021-A06). S.M. acknowledges support from the Research Council of Finland project 350458. D.P. acknowledges support by the Huo Family Foundation through a P.C. Ho PhD Studentship. E.E., B.D.J., G.R., and B.E.R. acknowledge support from the JWST/NIRCam contract with the University of Arizona, NAS 5-02015. B.E.R. also acknowledges support from the JWST Program 3215. S.T. acknowledges support from Royal Society Research Grant G125142. The research of C.C.W. is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. The authors acknowledge use of the lux supercomputer at UC Santa Cruz, funded by NSF MRI grant AST 1828315.
