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Abstract We present JWST NIRCam imaging targeting 13z ~ 3 infrared-luminous (LIR ∼ 5 × 1012L⊙) galaxies from the ALESS survey with uniquely deep, high-resolution (0 08–0 16) Atacama Large Millimeter/submillimeter Array 870μm imaging. The 2.0–4.4μm (observed frame) NIRCam imaging reveals the rest-frame near-infrared stellar emission in these submillimeter-selected galaxies at the same (sub)kiloparsec resolution as the 870μm dust continuum. The newly revealed stellar morphologies show striking similarities with the dust continuum morphologies at 870μm, with the centers and position angles agreeing for most sources, clearly illustrating that the spatial offsets reported previously between the 870μm and Hubble Space Telescope morphologies were due to strong differential dust obscuration. The F444W sizes are 78% ± 21% larger than those measured at 870μm, in contrast to recent results from hydrodynamical simulations that predict larger 870μm sizes. We report evidence for significant dust obscuration in F444W for the highest-redshift sources, emphasizing the importance of longer-wavelength MIRI imaging. The majority of the sources show evidence that they are undergoing mergers/interactions, including tidal tails/plumes—some of which are also detected at 870μm. We find a clear correlation between NIRCam colors and 870μm surface brightness on ∼1 kpc scales, indicating that the galaxies are primarily red due to dust—not stellar age—and we show that the dust structure on ∼kpc scales is broadly similar to that in nearby galaxies. Finally, we find no strong stellar bars in the rest-frame near-infrared, suggesting the extended bar-like features seen at 870μm are highly obscured and/or gas-dominated structures that are likely early precursors to significant bulge growth.
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This content will become publicly available on September 1, 2026
Even redder than we knew: Color and A V evolution up to z = 2.5 from JWST/NIRCam photometry
Aims.JWST/NIRCam provides rest-frame near-IR photometry of galaxies up toz = 2.5 with exquisite depth and accuracy. This affords us an unprecedented view of the evolution of the UV/optical/near-IR color distribution and its interpretation in terms of the evolving dust attenuation,AV. Methods.We used the value-added data products (photometric redshift, stellar mass, rest-frameU − VandV − Jcolors, andAV) provided by the public DAWN JWST Archive. These data products derive from fitting the spectral energy distributions obtained from multiple NIRCam imaging surveys, augmented with preexisting HST imaging data. Our sample consists of a stellar-mass-complete sample of ≈28 000M⋆ > 109 M⊙galaxies in the redshift range 0.5 < z < 2.5. Results.TheV − Jcolor distribution of star-forming galaxies evolves strongly, in particular for high-mass galaxies (M⋆ > 3 × 1010 M⊙), which have a pronounced tail of very red galaxies reachingV − J > 2.5 atz > 1.5 that does not exist atz < 1. Such redV − Jcan only be explained by dust attenuation, with typical values forM⋆ ≈ 1011 M⊙galaxies in the rangeAV ≈ 1.5 − 3.5 atz ≈ 2. This redshift evolution went largely unnoticed before. Today, however, photometric redshift estimates for the reddest (V − J > 2.5), most attenuated galaxies have markedly improved thanks to the new, precise photometry, which is in much better agreement with the 25 available spectroscopic redshifts for such galaxies. The reddest population readily stands out as the independently identified population of galaxies detected at submillimeter wavelengths. Despite the increased attenuation,U − Vcolors across the entire mass range are slightly bluer at higherz. A well-defined and tight color sequence exists at redshifts 0.5 < z < 2.5 forM⋆ > 3 × 1010 M⊙quiescent galaxies, in bothU − VandV − J, but inV − Jit is bluer rather than redder compared to star-forming galaxies. In conclusion, whereas the rest-frame UV-optical color distribution evolves remarkably little fromz = 0.5 toz = 2.5, the rest-frame optical/near-IR color distribution evolves strongly, primarily due to a very substantial increase with redshift in dust attenuation for massive galaxies.
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- Award ID(s):
- 2206473
- PAR ID:
- 10638718
- Publisher / Repository:
- Astronomy & Astrophysics
- Date Published:
- Journal Name:
- Astronomy & Astrophysics
- Volume:
- 701
- ISSN:
- 0004-6361
- Page Range / eLocation ID:
- A30
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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