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

Creators: Finkelstein, Steven L.¹; Bagley, Micaela B.¹; Arrabal Haro, Pablo²; Dickinson, Mark²; Ferguson, Henry C.³; Kartaltepe, Jeyhan S.⁴; Papovich, Casey⁵; Burgarella, Denis⁶; Kocevski, Dale D.⁷; Huertas-Company, Marc^{8, 9, 10}; Iyer, Kartheik G.¹¹; Koekemoer, Anton M.³; Larson, Rebecca L.^{1, 12}; Pérez-González, Pablo G.¹³; Rose, Caitlin⁴; Tacchella, Sandro¹⁴; Wilkins, Stephen M.^{15, 16}; Chworowsky, Katherine^{1, 17}; Medrano, Aubrey¹; Morales, Alexa M.¹; Somerville, Rachel S.¹⁸; Yung, L. Y. Aaron¹⁹; Fontana, Adriano²⁰; Giavalisco, Mauro²¹; Grazian, Andrea²²; Grogin, Norman A.³; Kewley, Lisa J.²³; Kirkpatrick, Allison²⁴; Kurczynski, Peter²⁵; Lotz, Jennifer M.²; Pentericci, Laura²⁰; Pirzkal, Nor³; Ravindranath, Swara³; Ryan, Russell E.³; Trump, Jonathan R.²⁶; Yang, Guang^{27, 28}; Almaini, Omar²⁹; Amorín, Ricardo O.³⁰; Annunziatella, Marianna¹³; Backhaus, Bren E.²⁶; Barro, Guillermo³¹; Behroozi, Peter^{32, 33}; Bell, Eric F.³⁴; Bhatawdekar, Rachana³⁵; Bisigello, Laura^{22, 36}; Bromm, Volker¹; Buat, Véronique⁶; Buitrago, Fernando^{37, 38}; Calabrò, Antonello²⁰; Casey, Caitlin M.¹; Castellano, Marco²⁰; Chávez Ortiz, Óscar A.¹; Ciesla, Laure⁶; Cleri, Nikko J.⁵; Cohen, Seth H.³⁹; Cole, Justin W.⁵; Cooke, Kevin C.⁴⁰; Cooper, M. C.⁴¹; Cooray, Asantha R.⁴¹; Costantin, Luca¹³; Cox, Isabella G.⁴; Croton, Darren^{42, 43}; Daddi, Emanuele¹⁰; Davé, Romeel^{44, 45}; de la Vega, Alexander⁴⁶; Dekel, Avishai⁴⁷; Elbaz, David¹⁰; Estrada-Carpenter, Vicente⁴⁸; Faber, Sandra M.⁴⁹; Fernández, Vital³⁰; Finkelstein, Keely D.¹; Freundlich, Jonathan⁵⁰; Fujimoto, Seiji⁵¹; García-Argumánez, Ángela⁵²; Gardner, Jonathan P.¹⁹; Gawiser, Eric⁵³; Gómez-Guijarro, Carlos¹⁰; Guo, Yuchen¹; Hamblin, Kurt²⁴; Hamilton, Timothy S.⁵⁴; Hathi, Nimish P.³; Holwerda, Benne W.⁵⁵; Hirschmann, Michaela⁵⁶; Hutchison, Taylor A.^{5, 12}; Jaskot, Anne E.⁵⁷; Jha, Saurabh W.⁵³; Jogee, Shardha¹; Juneau, Stéphanie²; Jung, Intae^{19, 58, 25}; Kassin, Susan A.^{3, 46}; Le Bail, Aurélien¹⁰; Leung, Gene C. K.¹; Lucas, Ray A.³; Magnelli, Benjamin¹⁰; Mantha, Kameswara Bharadwaj⁵⁹; Matharu, Jasleen⁵; McGrath, Elizabeth J.⁷; McIntosh, Daniel H.⁶⁰; Merlin, Emiliano²⁰; Mobasher, Bahram⁶¹; Newman, Jeffrey A.⁶²; Nicholls, David C.⁶³; Pandya, Viraj^{64, 65}; Rafelski, Marc^{3, 46}; Ronayne, Kaila⁵; Santini, Paola²⁰; Seillé, Lise-Marie⁶; Shah, Ekta A.⁶⁶; Shen, Lu⁶⁷; Simons, Raymond C.³; Snyder, Gregory F.³; Stanway, Elizabeth R.⁶⁸; Straughn, Amber N.¹⁹; Teplitz, Harry I.⁶⁹; Vanderhoof, Brittany N.⁴; Vega-Ferrero, Jesús⁸; Wang, Weichen⁴⁶; Weiner, Benjamin J.³²; Willmer, Christopher N. A.³²; Wuyts, Stijn⁷⁰; Zavala, Jorge A.³³; CEERS Team

1. The University of Texas at Austin
2. NOIRLab
3. Space Telescope Science Institute
4. Rochester Institute of Technology
5. Texas A&M University
6. Aix Marseille Univ, CNRS, CNES, LAM Marseille, France
7. Colby College
8. Instituto de Astrofísica de Canarias
9. University of La Laguna
10. University of Paris
11. University of Toronto
12. NSF Graduate Fellow
13. Centro de Astrobiología
14. University of Cambridge
15. University of Sussex
16. University of Malta
17. NSF Graduate Fellow.
18. Center for Computational Astrophysics, Flatiron Institute, 162 5th Avenue, New York, NY 10010, USA
19. Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA
20. Astronomical Observatory of Rome
21. University of Massachusetts Amherst
22. Osservatorio Astronomico di Padova
23. Harvard-Smithsonian Center for Astrophysics
24. University of Kansas
25. Goddard Space Flight Center
26. University of Connecticut
27. University of Groningen
28. Netherlands Institute for Space Research
29. University of Nottingham
30. University of La Serena
31. University of the Pacific
32. University of Arizona
33. National Astronomical Observatory of Japan
34. University of Michigan–Ann Arbor
35. European Space Research and Technology Centre
36. University of Padua
37. University of Valladolid
38. University of Lisbon
39. Arizona State University
40. American Association For The Advancement of Science
41. University of California, Irvine
42. Swinburne University of Technology
43. Centre of Excellence for All-Sky Astrophysics
44. University of Edinburgh
45. University of the Western Cape
46. Johns Hopkins University
47. Hebrew University of Jerusalem
48. Saint Mary's University
49. University of California, Santa Cruz
50. Observatory of Strasbourg
51. University of Copenhagen
52. Complutense University of Madrid
53. Rutgers, The State University of New Jersey
54. Shawnee State University
55. University of Louisville
56. École Polytechnique Fédérale de Lausanne
57. Williams College
58. Catholic University of America
59. University of Minnesota
60. University of Missouri–Kansas City
61. University of California, Riverside
62. University of Pittsburgh
63. Australian National University
64. Columbia University
65. Hubble Fellow.
66. University of California, Davis
67. University of Science and Technology of China
68. University of Warwick
69. California Institute of Technology
70. University of Bath

Abstract

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.

Copyright and License

Funding

We acknowledge support from NASA through STScI ERS award JWST-ERS-1345. D.B. and M.H.-C. thank the Programme National de Cosmologie et Galaxies and CNES for their support. R.A. acknowledges support from Fondecyt Regular 1202007.

Acknowledgement

We acknowledge that the location where this work took place, the University of Texas at Austin, sits on indigenous land. The Tonkawa lived in central Texas, and the Comanche and Apache moved through this area. We pay our respects to all of the American Indian and Indigenous Peoples and communities who have been or have become a part of these lands and territories in Texas on this piece of Turtle Island.

We thank the entire JWST team, including the engineers, for making possible this wonderful overperforming telescope, the commissioning team for obtaining these early data, and the pipeline teams for their work over the years building and supporting the pipeline. The authors acknowledge the Texas Advanced Computing Center (TACC) at the University of Texas at Austin for providing HPC and visualization resources that have contributed to the research results reported within this paper. We thank Brendan Bowler, Caroline Morley, Jim Dunlop, and Mike Boylan-Kolchin for helpful conversations and the anonymous referee for constructive comments.

Software References

Astropy (Astropy Collaboration et al. 2013), Bagpipes (Carnall et al. 2018), Cigale (Burgarella et al. 2005; Noll et al. 2009; Boquien et al. 2019), Dense Basis (Iyer & Gawiser 2017; Iyer et al. 2019), Drizzle (Fruchter & Hook 2002), eazy (Brammer et al. 2008), GalfitM (Peng et al. 2010; Häußler et al. 2013), Photutils (Bradley et al. 2020), Prospector (Johnson et al. 2021), SciPy (Virtanen et al. 2020), SExtractor (Bertin & Arnouts 1996), Statmorph (Rodriguez-Gomez et al. 2019), STScI JWST Calibration Pipeline (jwst-pipeline.readthedocs.io).

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