MACS0647-JD is a triply lensed z ∼ 11 galaxy originally discovered with the Hubble Space Telescope. The three lensed images are magnified by factors of ∼8, 5, and 2 to AB mag 25.1, 25.6, and 26.6 at 3.5 μm. The brightest is over a magnitude brighter than other galaxies recently discovered at similar redshifts z > 10 with JWST. Here, we report new JWST imaging that clearly resolves MACS0647-JD as having two components that are either merging galaxies or stellar complexes within a single galaxy. The brighter larger component “A” is intrinsically very blue (β ∼ −2.6 ± 0.1), likely due to very recent star formation and no dust, and is spatially extended with an effective radius ∼70 ± 24 pc. The smaller component “B” (r ∼ 20 − 5 + 8 pc) appears redder (β ∼ −2 ± 0.2), likely because it is older (100-200 Myr) with mild dust extinction (A V ∼ 0.1 mag). With an estimated stellar mass ratio of roughly 2:1 and physical projected separation ∼400 pc, we may be witnessing a galaxy merger 430 million years after the Big Bang. We identify galaxies with similar colors in a high-redshift simulation, finding their star formation histories to be dissimilar, which is also suggested by the spectral energy distribution fitting, suggesting they formed further apart. We also identify a candidate companion galaxy “C” ∼3 kpc away, likely destined to merge with A and B. Upcoming JWST Near Infrared Spectrograph observations planned for 2023 January will deliver spectroscopic redshifts and more physical properties for these tiny magnified distant galaxies observed in the early universe.

JWST Reveals a Possible z ~11 Galaxy Merger in Triply Lensed MACS0647-JD / Tiger Yu-Yang Hsiao, D. Coe, Abdurro???uf, L. Whitler, I. Jung, G. Khullar, Ashish Kumar Meena, P. Dayal, K.S.S. Barrow, L. Santos-Olmsted, A. Casselman, E. Vanzella, M. Nonino, Y. Jim??nez-Teja, M. Oguri, D.P. Stark, L.J. Furtak, A. Zitrin, A. Adamo, G. Brammer, L. Bradley, J.M. Diego, E. Zackrisson, S.L. Finkelstein, R.A. Windhorst, R. Bhatawdekar, T.A. Hutchison, T. Broadhurst, P. Dimauro, F. Andrade-Santos, J.J. Eldridge, A. Acebron, R.J. Avila, M.B. Bayliss, A. Ben??tez, C. Binggeli, P. Bolan, M. Brada??, A.C. Carnall, C.J. Conselice, M. Donahue, B. Frye, S. Fujimoto, A. Henry, B.L. James, S.A. Kassin, L. Kewley, R.L. Larson, T. Lauer, D. Law, G. Mahler, R. Mainali, S. Mccandliss, D. Nicholls, N. Pirzkal, M. Postman, J.R. Rigby, R. Ryan, P. Senchyna, K. Sharon, I. Shimizu, V. Strait, M. Tang, M. Trenti, A. Vikaeus, B. Welch. - In: THE ASTROPHYSICAL JOURNAL LETTERS. - ISSN 2041-8205. - 949:2(2023 Jun 02), pp. L34.1-L34.21. [10.3847/2041-8213/acc94b]

JWST Reveals a Possible z ~11 Galaxy Merger in Triply Lensed MACS0647-JD

A. Acebron;
2023

Abstract

MACS0647-JD is a triply lensed z ∼ 11 galaxy originally discovered with the Hubble Space Telescope. The three lensed images are magnified by factors of ∼8, 5, and 2 to AB mag 25.1, 25.6, and 26.6 at 3.5 μm. The brightest is over a magnitude brighter than other galaxies recently discovered at similar redshifts z > 10 with JWST. Here, we report new JWST imaging that clearly resolves MACS0647-JD as having two components that are either merging galaxies or stellar complexes within a single galaxy. The brighter larger component “A” is intrinsically very blue (β ∼ −2.6 ± 0.1), likely due to very recent star formation and no dust, and is spatially extended with an effective radius ∼70 ± 24 pc. The smaller component “B” (r ∼ 20 − 5 + 8 pc) appears redder (β ∼ −2 ± 0.2), likely because it is older (100-200 Myr) with mild dust extinction (A V ∼ 0.1 mag). With an estimated stellar mass ratio of roughly 2:1 and physical projected separation ∼400 pc, we may be witnessing a galaxy merger 430 million years after the Big Bang. We identify galaxies with similar colors in a high-redshift simulation, finding their star formation histories to be dissimilar, which is also suggested by the spectral energy distribution fitting, suggesting they formed further apart. We also identify a candidate companion galaxy “C” ∼3 kpc away, likely destined to merge with A and B. Upcoming JWST Near Infrared Spectrograph observations planned for 2023 January will deliver spectroscopic redshifts and more physical properties for these tiny magnified distant galaxies observed in the early universe.
Settore FIS/05 - Astronomia e Astrofisica
   Unveiling the formation and evolution of galaxy clusters through the intracluster light and multidisciplinar techniques of image processing and big data analysis
   CICLE
   European Commission
   Horizon 2020 Framework Programme
   898633
2-giu-2023
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1019974
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