JWST reveals a possible $z\sim 11$ galaxy merger in triply-lensed MACS0647$-$JD

Abstract

MACS0647$-$JD is a triply-lensed $z\sim 11$ galaxy originally discovered with the Hubble Space Telescope. Here we report new JWST imaging, which clearly resolves MACS0647$-$JD as having two components that are either merging galaxies or stellar complexes within a single galaxy. Both are very small, with stellar masses $\sim 10^8{M}_{\odot }$ and radii $r<100\mathrm{pc}$. The brighter larger component "A" is intrinsically very blue ($\beta \sim -2.6$), likely due to very recent star formation and no dust, and is spatially extended with an effective radius $\sim 70\mathrm{pc}$. The smaller component "B" appears redder ($\beta \sim -2$), likely because it is older ($100-200\mathrm{Myr}$) with mild dust extinction ($A_V\sim 0.1\mathrm{mag}$), and a smaller radius $\sim 20\mathrm{pc}$. We identify galaxies with similar colors in a high-redshift simulation, finding their star formation histories to be out of phase. With an estimated stellar mass ratio of roughly 2:1 and physical projected separation $\sim 400\mathrm{pc}$, we may be witnessing a galaxy merger 400 million years after the Big Bang. We also identify a candidate companion galaxy C $\sim 3\mathrm{kpc}$ away, likely destined to merge with galaxies A and B. The combined light from galaxies A+B is magnified by factors of $\sim$8, 5, and 2 in three lensed images JD1, 2, and 3 with F356W fluxes $\sim 322$, $203$, $86\mathrm{nJy}$ (AB mag 25.1, 25.6, 26.6). MACS0647$-$JD is significantly brighter than other galaxies recently discovered at similar redshifts with JWST. Without magnification, it would have AB mag 27.3 ($M_{UV}=-20.4$). With a high confidence level, we obtain a photometric redshift of $z=10.6\pm 0.3$ based on photometry measured in 6 NIRCam filters spanning $1-5\mu \mathrm{m}$, out to $4300\mathring{A}$ rest-frame. JWST NIRSpec observations planned for January 2023 will deliver a spectroscopic redshift and a more detailed study of the physical properties of MACS0647$-$JD.

27 pages, 14 figures, accepted for publication in ApJL

References in corpus (66)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Cosmic Star Formation History
• The James Webb Space Telescope
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• EAZY: A Fast, Public Photometric Redshift Code
• Cold streams in early massive hot haloes as the main mode of galaxy formation
• Constraining the Low-Mass Slope of the Star Formation Sequence at 0.5<z<2.5
• Stellar Population Inference with Prospector
• A Bayesian approach to strong lensing modelling of galaxy clusters
• A Comprehensive Study on Galaxies at z~9-16 Found in the Early JWST Data: UV Luminosity Functions and Cosmic Star-Formation History at the Pre-Reionization Epoch
• Two Remarkably Luminous Galaxy Candidates at $z\approx 10-12$ Revealed by JWST
• The Science Performance of JWST as Characterized in Commissioning
• The evolution of the galaxy UV luminosity function at redshifts z ~ 8-15 from deep JWST and ground-based near-infrared imaging
• Evolution of asymptotic giant branch stars I. Updated synthetic TP-AGB models and their basic calibration
• A Long Time Ago in a Galaxy Far, Far Away: A Candidate z ~ 12 Galaxy in Early JWST CEERS Imaging
• Early results from GLASS-JWST. III: Galaxy candidates at z$\sim$9-15
• Modelling the nebular emission from primeval to present-day star-forming galaxies
• A complete sample of twelve very X-ray luminous galaxy clusters at z>0.5
• Hubble Space Telescope Combined Strong and Weak Lensing Analysis of the CLASH Sample: Mass and Magnification Models and Systematic Uncertainties
• CLASH: Weak-Lensing Shear-and-Magnification Analysis of 20 Galaxy Clusters
• Imfit: A Fast, Flexible New Program for Astronomical Image Fitting
• Discovery and properties of ultra-high redshift galaxies ($9<z<12$) in the JWST ERO SMACS 0723 Field
• A time-resolved picture of our Milky Way's early formation history
• Revealing Galaxy Candidates out to $z\sim 16$ with JWST Observations of the Lensing Cluster SMACS0723
• Multi-scale cluster lens mass mapping I. Strong Lensing modelling
• CLASH: The Concentration-Mass Relation of Galaxy Clusters
• On the Stellar Populations of Galaxies at z=9-11: The Growth of Metals and Stellar Mass at Early Times
• Reionization Era Bright Emission Line Survey: Selection and Characterization of Luminous Interstellar Medium Reservoirs in the z>6.5 Universe
• A definitive merger-AGN connection at z~0 with CFIS: mergers have an excess of AGN and AGN hosts are more frequently disturbed
• Observational constraints on the merger history of galaxies since $z\approx 6$: Probabilistic galaxy pair counts in the CANDELS fields
• Reconstructing the Last Major Merger of the Milky Way with the H3 Survey
• Essential physics of early galaxy formation
• Panic! At the Disks: First Rest-frame Optical Observations of Galaxy Structure at $z>3$ with JWST in the SMACS 0723 Field
• The ALMA REBELS Survey: the dust content of $z\sim 7$ Lyman Break Galaxies
• Astraeus I: The interplay between galaxy formation and reionization
• Star formation at the smallest scales; A JWST study of the clump populations in SMACS0723
• First Batch of Candidate Galaxies at Redshifts 11 to 20 Revealed by the James Webb Space Telescope Early Release Observations
• Reionization with galaxies and active galactic nuclei
• Timing the Early Assembly of the Milky Way with the H3 Survey
• New Insights into the Evolution of Massive Stars and Their Effects on Our Understanding of Early Galaxies
• Star formation histories of UV-luminous galaxies at $z\simeq 6.8$: implications for stellar mass assembly at early cosmic times
• The ALPINE-ALMA [CII] Survey: Obscured Star Formation Rate Density and Main Sequence of star-forming galaxies at z>4
• High star cluster formation efficiency in the strongly lensed Sunburst Lyman-continuum galaxy at z=2.37
• The ALMA REBELS Survey: Specific Star-Formation Rates in the Reionization Era
• On the ages of bright galaxies $\sim 500$ Myr after the Big Bang: insights into star formation activity at $z\gtrsim 15$ with JWST
• Ultraviolet Morphologies and Star-Formation Rates of CLASH Brightest Cluster Galaxies
• Trinity I: Self-Consistently Modeling the Dark Matter Halo-Galaxy-Supermassive Black Hole Connection from $z=0-10$
• JWST Imaging of Earendel, the Extremely Magnified Star at Redshift $z=6.2$
• Exploring the physical properties of lensed star-forming clumps at $2\lesssim z\lesssim 6$
• Constraining the physical properties of the first lensed $z\sim 10-16$ galaxy candidates with JWST
• The discovery of rest-frame UV colour gradients and a diversity of dust morphologies in bright z ~ 7 Lyman-break galaxies
• Unscrambling the lensed galaxies in JWST images behind SMACS0723
• The merger and assembly histories of Milky Way- and M31-like galaxies with TNG50: disk survival through mergers
• The Lyman Continuum Escape Survey: Connecting Time-Dependent [OIII] and [OII] Line Emission with Lyman Continuum Escape Fraction in Simulations of Galaxy Formation
• Introducing piXedfit -- a Spectral Energy Distribution Fitting Code Designed for Resolved Sources
• JWST/NIRCam Observations of Stars and HII Regions in $z\simeq 6-8$ Galaxies: Properties of Star Forming Complexes on 150 pc Scales
• The assembly of dusty galaxies at $z\ge 4$: the build-up of stellar mass and its scaling relations with hints from early JWST data
• Early results from GLASS-JWST. X: Rest-frame UV-optical properties of galaxies at 7 < z < 9
• Spatially Resolved Stellar Populations of $0.3<z<6.0$ Galaxies in WHL0137-08 and MACS0647+70 Clusters as Revealed by JWST: How do Galaxies Grow and Quench Over Cosmic Time?
• Crowded Field Galaxy Photometry: Precision Colors in the CLASH Clusters
• RELICS: Small-scale Star Formation in Lensed Galaxies at $z=6-10$
• The buildup of galaxies and their spheroids: the contributions of mergers, disc instabilities and star formation
• Geometric Corroboration of the Earliest Lensed Galaxy at z~10.8 from Robust Free-Form Modelling
• Deep Spitzer/IRAC Data for z~10 galaxies Reveal Blue Balmer Break Colors: Young Stellar Populations at ~500 Myr of Cosmic Time
• Not In Our Backyard: Spectroscopic Support for the CLASH z=11 Candidate MACS0647-JD
• Astraeus VII: The environmental-dependent assembly of galaxies in the Epoch of Reionization

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