TY - JOUR

T1 - JWST Reveals a Possible z ∼ 11 Galaxy Merger in Triply Lensed MACS0647-JD

AU - Hsiao, Tiger Yu Yang

AU - Coe, Dan

AU - Abdurro’uf, null

AU - Whitler, Lily

AU - Jung, Intae

AU - Khullar, Gourav

AU - Meena, Ashish Kumar

AU - Dayal, Pratika

AU - Barrow, Kirk S.S.

AU - Santos-Olmsted, Lillian

AU - Casselman, Adam

AU - Vanzella, Eros

AU - Nonino, Mario

AU - Jiménez-Teja, Yolanda

AU - Oguri, Masamune

AU - Stark, Daniel P.

AU - Furtak, Lukas J.

AU - Zitrin, Adi

AU - Adamo, Angela

AU - Brammer, Gabriel

AU - Bradley, Larry

AU - Diego, Jose M.

AU - Zackrisson, Erik

AU - Finkelstein, Steven L.

AU - Windhorst, Rogier A.

AU - Bhatawdekar, Rachana

AU - Hutchison, Taylor A.

AU - Broadhurst, Tom

AU - Dimauro, Paola

AU - Andrade-Santos, Felipe

AU - Eldridge, Jan J.

AU - Acebron, Ana

AU - Avila, Roberto J.

AU - Bayliss, Matthew B.

AU - Benítez, Alex

AU - Binggeli, Christian

AU - Bolan, Patricia

AU - Bradač, Maruša

AU - Carnall, Adam C.

AU - Conselice, Christopher J.

AU - Donahue, Megan

AU - Frye, Brenda

AU - Fujimoto, Seiji

AU - Henry, Alaina

AU - James, Bethan L.

AU - Kassin, Susan A.

AU - Kewley, Lisa

AU - Larson, Rebecca L.

AU - Lauer, Tod

AU - Law, David

AU - Mahler, Guillaume

AU - Mainali, Ramesh

AU - McCandliss, Stephan

AU - Nicholls, David

AU - Pirzkal, Norbert

AU - Postman, Marc

AU - Rigby, Jane R.

AU - Ryan, Russell

AU - Senchyna, Peter

AU - Sharon, Keren

AU - Shimizu, Ikko

AU - Strait, Victoria

AU - Tang, Mengtao

AU - Trenti, Michele

AU - Vikaeus, Anton

AU - Welch, Brian

N1 - Publisher Copyright: © 2023. The Author(s). Published by the American Astronomical Society.

PY - 2023/6/2

Y1 - 2023/6/2

N2 - 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.

AB - 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.

U2 - 10.3847/2041-8213/acc94b

DO - 10.3847/2041-8213/acc94b

M3 - Letter

AN - SCOPUS:85161474266

VL - 949

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

SN - 2041-8205

IS - 2

M1 - L34

ER -