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A Long Time Ago in a Galaxy Far, Far Away: A Candidate z ∼ 12 Galaxy in Early JWST CEERS Imaging

Finkelstein, Steven L.; Bagley, Micaela B.; Haro, Pablo Arrabal; Dickinson, Mark; Ferguson, Henry C.; Kartaltepe, Jeyhan S.; Papovich, Casey; Burgarella, Denis; Kocevski, Dale D.; Huertas-Company, Marc; Iyer, Kartheik G.; Koekemoer, Anton M.; Larson, Rebecca L.; Pérez-González, Pablo G.; Rose, Caitlin; Tacchella, Sandro; Wilkins, Stephen M.; Chworowsky, Katherine; Medrano, Aubrey; Morales, Alexa M.; Somerville, Rachel S.; Yung, L. Y. Aaron; Fontana, Adriano; Giavalisco, Mauro; Grazian, Andrea; Grogin, Norman A.; Kewley, Lisa J.; Kirkpatrick, Allison; Kurczynski, Peter; Lotz, Jennifer M.; Pentericci, Laura; Pirzkal, Nor; Ravindranath, Swara; Ryan, Russell E.; Trump, Jonathan R.; Yang, Guang; Almaini, Omar; Amorín, Ricardo O.; Annunziatella, Marianna; Backhaus, Bren E.; Barro, Guillermo; Behroozi, Peter; Bell, Eric F.; Bhatawdekar, Rachana; Bisigello, Laura; Bromm, Volker; Buat, Véronique; Buitrago, Fernando; Calabrò, Antonello; Casey, Caitlin M.; Castellano, Marco; Chávez Ortiz, Oscar...

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Steven L. Finkelstein

Micaela B. Bagley

Pablo Arrabal Haro

Mark Dickinson

Henry C. Ferguson

Jeyhan S. Kartaltepe

Casey Papovich

Denis Burgarella

Dale D. Kocevski

Marc Huertas-Company

Kartheik G. Iyer

Anton M. Koekemoer

Rebecca L. Larson

Pablo G. Pérez-González

Caitlin Rose

Sandro Tacchella

Stephen M. Wilkins

Katherine Chworowsky

Aubrey Medrano

Alexa M. Morales

Rachel S. Somerville

L. Y. Aaron Yung

Adriano Fontana

Mauro Giavalisco

Andrea Grazian

Norman A. Grogin

Lisa J. Kewley

Allison Kirkpatrick

Peter Kurczynski

Jennifer M. Lotz

Laura Pentericci

Nor Pirzkal

Swara Ravindranath

Russell E. Ryan

Jonathan R. Trump

Guang Yang

Professor of Astrophysics

Ricardo O. Amorín

Marianna Annunziatella

Bren E. Backhaus

Guillermo Barro

Peter Behroozi

Eric F. Bell

Rachana Bhatawdekar

Laura Bisigello

Volker Bromm

Véronique Buat

Fernando Buitrago

Antonello Calabrò

Caitlin M. Casey

Marco Castellano

Oscar A. Chávez Ortiz

Laure Ciesla

Nikko J. Cleri

Seth H. Cohen

Justin W. Cole

Kevin C. Cooke

M. C. Cooper

Asantha R. Cooray

Luca Costantin

Isabella G. Cox

Darren Croton

Emanuele Daddi

Romeel Davé

Alexander De La Vega

Avishai Dekel

David Elbaz

Vicente Estrada-Carpenter

Sandra M. Faber

Vital Fernández

Keely D. Finkelstein

Jonathan Freundlich

Seiji Fujimoto

Angela García-Argumánez

Jonathan P. Gardner

Eric Gawiser

Carlos Gómez-Guijarro

Yuchen Guo

Kurt Hamblin

Timothy S. Hamilton

Nimish P. Hathi

Benne W. Holwerda

Michaela Hirschmann

Taylor A. Hutchison

Anne E. Jaskot

Saurabh W. Jha

Shardha Jogee

Stéphanie Juneau

Intae Jung

Susan A. Kassin

Aurélien Le Bail

Gene C. K. Leung

Ray A. Lucas

Benjamin Magnelli

Kameswara Bharadwaj Mantha

Jasleen Matharu

Elizabeth J. McGrath

Daniel H. McIntosh

Emiliano Merlin

Bahram Mobasher

Jeffrey A. Newman

David C. Nicholls

Viraj Pandya

Marc Rafelski

Kaila Ronayne

Paola Santini

Lise-Marie Seillé

Ekta A. Shah

Lu Shen

Raymond C. Simons

Gregory F. Snyder

Elizabeth R. Stanway

Amber N. Straughn

Harry I. Teplitz

Brittany N. Vanderhoof

Jesús Vega-Ferrero

Weichen Wang

Benjamin J. Weiner

Christopher N .A. Willmer

Stijn Wuyts

Jorge A. Zavala


We report the discovery of a candidate galaxy with a photo-z of z ∼ 12 in the first epoch of the James Webb Space Telescope (JWST) Cosmic Evolution Early Release Science Survey. Following conservative selection criteria, we identify a source with a robust z phot = 11.8−0.2+0.3 (1σ uncertainty) with m F200W = 27.3 and ≳7σ detections in five filters. The source is not detected at λ < 1.4 μm in deep imaging from both Hubble Space Telescope (HST) and JWST and has faint ∼3σ detections in JWST F150W and HST F160W, which signal a Lyα break near the red edge of both filters, implying z ∼ 12. This object (Maisie’s Galaxy) exhibits F115W − F200W > 1.9 mag (2σ lower limit) with a blue continuum slope, resulting in 99.6% of the photo-z probability distribution function favoring z > 11. All data-quality images show no artifacts at the candidate’s position, and independent analyses consistently find a strong preference for z > 11. Its colors are inconsistent with Galactic stars, and it is resolved (r h = 340 ± 14 pc). Maisie’s Galaxy has log M */M ⊙ ∼ 8.5 and is highly star-forming (log sSFR ∼ −8.2 yr−1), with a blue rest-UV color (β ∼ −2.5) indicating little dust, though not extremely low metallicity. While the presence of this source is in tension with most predictions, it agrees with empirical extrapolations assuming UV luminosity functions that smoothly decline with increasing redshift. Should follow-up spectroscopy validate this redshift, our universe was already aglow with galaxies less than 400 Myr after the Big Bang.


Finkelstein, S. L., Bagley, M. B., Haro, P. A., Dickinson, M., Ferguson, H. C., Kartaltepe, J. S., …Zavala, J. A. (2022). A Long Time Ago in a Galaxy Far, Far Away: A Candidate z ∼ 12 Galaxy in Early JWST CEERS Imaging. Astrophysical Journal Letters, 940(2), Article L55.

Journal Article Type Article
Acceptance Date Sep 2, 2022
Online Publication Date Dec 1, 2022
Publication Date Dec 1, 2022
Deposit Date Sep 28, 2022
Publicly Available Date Dec 1, 2022
Journal Astrophysical Journal Letters
Print ISSN 2041-8205
Electronic ISSN 2041-8213
Peer Reviewed Peer Reviewed
Volume 940
Issue 2
Article Number L55
Keywords Early universe (435); Galaxy formation (595); Galaxy evolution (594); High-redshift galax- ies (734)
Public URL
Publisher URL
Related Public URLs
Additional Information Authors on behalf of the CEERS Team


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