AstroNote 2024-264

The JWST Advanced Deep Extragalactic Survey (JADES) obtained a set of 9-band JWST/NIRCam images of GOODS-N (PID: 1181, PI: Eisenstein), using 4 short-wavelength filters (F090W, F115W, F150W, and F200W) and 5 long-wavelength filters (F277W, F335M, F356W, F410M, and F444W). These images were taken on UT Feb 3, 2023. The Complete NIRCam Grism Redshift Survey (CONGRESS) obtained a set of 3-band JWST/NIRCam images of GOODS-N (PID: 3577, PI: Egami), using 2 short-wavelength filters (F090W, F115W) and 1 long-wavelength filter (F356W). These images were taken on UT Feb 12-18, 2024. 

We produced difference images for the three common filters (F090W, F115W, and F356W) and discovered transients/variables by searching for point-like emission in the difference images. We discovered 39 transients/variables, 18 of which brightened from 2023 to 2024 and 21 of which faded from 2023 to 2024. We also found 16 of the 17 transients reported in AstroNote 2023-164, which compares the 2023 JADES NIRCam images of GOODS-N to Hubble images of GOODS-N taken from the Hubble Legacy Field archive. The one transient from this JADES-HST AstroNote that was not re-discovered falls outside of the overlapping region between the JADES and CONGRESS images.

We attached a zip file containing multi-filter 2023, 2024, and difference images for each newly-discovered transient/variable source. The magnitudes reported on these images are AB magnitudes. Host redshifts are either spectroscopic redshifts obtained from the literature (Momcheva et al. 2016; Barger, Cowie, & Wang  2008; Oesch et al. 2023; Kriek et al. 2015; Sun et al. 2024), or photometric redshifts obtained by Hainline et al. (2024) using EAZY (Brammer et al. 2008).

The majority of the transients reported are likely supernovae (SNe), as they appear as point-like sources that visibly appear/disappear in multiple filters between the two sets of images. However, some signals detected in the difference images are on top of the host-galaxy nucleus, suggesting the possibility that they may be non-SN variable sources such as active galactic nuclei or tidal disruption events. AT2023adya is one such example, as this source shows clear evidence of variability in F356W but the source of variability is too close to the galactic nucleus to discern if a point source (i.e., supernova) fades from 2023 to 2024. This source, however, is particularly exciting as the host galaxy, JADES-GN+189.12004+62.23867, has a spectroscopic redshift of 5.271 (Sun et al. 2024), which demonstrates JWST’s capability of detecting variability at z>5. Notably, the host galaxy belongs to a high-redshift galaxy overdensity identified as JADES-GN-OD-5.269 in Helton et al. (2023).