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Arxiv: Birds of a Feather: Resolving Stellar Mass Assembly With JWST/NIRCam in a Pair of Kindred z \sim 2 Dusty Star-forming Galaxies Lensed by the PLCK G165.7+67.0 Cluster Published: 4/11/2024 9:02:08 PM Updated: 4/11/2024 9:02:08 PM

Paper abstract: We present a new parametric lens model for the G165.7+67.0 galaxy cluster,which was discovered with Planck through its bright submillimeter flux,originating from a pair of extraordinary dusty star-forming galaxies (DSFGs) atz~ 2.2. Using JWST and interferometric mm/radio observations, wecharacterize the intrinsic physical properties of the DSFGs, which areseparated by only ~ 1^{\prime\prime} (8 kpc) and a velocity difference\Delta V <~ 600~{\rm km}~{\rm s}^{-1} in the source plane, and thuslikely undergoing a major merger. Boasting intrinsic star formation rates {\rmSFR}_{\rm IR} = 320 \pm 70 and 400 \pm 80~ M_\odot~{\rm yr}^{-1}, stellarmasses {\rm log}[M_*/M_\odot] = 10.2 \pm 0.1 and 10.3 \pm 0.1, and dustattenuations A_V = 1.5 \pm 0.3 and 1.2 \pm 0.3, they are remarkably similarobjects. We perform spatially-resolved pixel-by-pixel SED fitting usingrest-frame near-UV to near-IR imaging from JWST/NIRCam for both galaxies,resolving some stellar structures down to 100 pc scales. Based on theirresolved specific SFRs and UVJ colors, both DSFGs are experiencingsignificant galaxy-scale star formation events. If they are indeed interactinggravitationally, this strong starburst could be the hallmark of gas that hasbeen disrupted by an initial close passage. In contrast, the host galaxy of therecently discovered triply-imaged SN H0pe has a much lower SFR than the DSFGs,and we present evidence for the onset of inside-out quenching and large columndensities of dust even in regions of low specific SFR. Based on the intrinsicSFRs of the DSFGs inferred from UV through FIR SED modeling, this pair ofobjects alone is predicted to yield an observable 1.1 \pm 0.2~{\rmCCSNe~yr}^{-1}, making this cluster field ripe for continued monitoring.