Nowhere Left to Hide: Uncovering All of the Massive Young Embedded Star Clusters in the Antennae with JWST*
Abstract The Antennae galaxies merger produces the brightest infrared emission of any galaxy within ≈20 Mpc, mostly from intense star formation taking place in supergiant molecular cloud complexes in the overlap region. Here, we present new, high-resolution NIRCam and MIRI images of the Antennae galaxies taken with the F150W, F187N, F335M, F360M, F410M, and F770W filters on JWST to search for the predicted but as-yet-undiscovered population of deeply embedded, optically obscured star clusters. We identify a population of 45 sources, 40 previously unknown, with high Br α /H α and Pa α /H α flux ratios, which are likely very young clusters still embedded or just emerging from their natal cocoons, and estimate their age, extinction ( A V ), and mass. We find that all are extremely young (≲2.5 Myr), have A V between 2 and 10 mag, and masses between ≈10 4 and several ×10 6 M ⊙ . We believe we have now uncovered all clusters with M ≳ 3 × 10 4 M ⊙ and A V ≳ 2 mag in the Antennae. While our sample represents a small fraction (≈15%) of clusters younger than 3 Myr by number, it dominates the ionizing photon luminosity across the galaxy pair (≈60%). We find elevated H 2 /polycyclic aromatic hydrocarbon ratios of the interstellar medium surrounding the most massive pair of embedded clusters, supporting the idea that merger-induced shock-heated gas plays an important role in the formation of extremely massive clusters.
Authors
- Karin M. Sandstrom (ORCID: https://orcid.org/0000-0002-4378-8534)
- J. D. Smith (ORCID: https://orcid.org/0000-0003-1545-5078)
- Miranda Caputo (ORCID: https://orcid.org/0000-0002-2957-3924)
- Angus Mok (ORCID: https://orcid.org/0000-0001-7413-7534)
- Fabian Walter (ORCID: https://orcid.org/0000-0003-4793-7880)
- Sara Duval
- Paul Goudfrooij (ORCID: https://orcid.org/0000-0002-5728-1427)
- Eva Schinnerer (ORCID: https://orcid.org/0000-0002-3933-7677)
- Sean T. Linden (ORCID: https://orcid.org/0000-0002-1000-6081)
- Ralf S. Klessen (ORCID: https://orcid.org/0000-0002-0560-3172)
- Cory M. Whitcomb (ORCID: https://orcid.org/0000-0003-2093-4452)
- Rupali Chandar (ORCID: https://orcid.org/0000-0003-0085-4623)
- Florent Renaud (ORCID: https://orcid.org/0000-0001-5073-2267)
- Grant Donnelly (ORCID: https://orcid.org/0000-0003-4986-2042)
- Lindsey Hands
- Alberto Bolatto
- Danny A. Dale (ORCID: https://orcid.org/0000-0002-5782-9093)
- Caroline Kuczek (ORCID: https://orcid.org/0009-0001-3989-1731)
Institutions
- University of Wyoming (US)
- Centre National de la Recherche Scientifique (FR)
- Space Telescope Science Institute (US)
- University of Arizona (US)
- Heidelberg University (DE)
- Observatoire astronomique de Strasbourg (FR)
- University of California San Diego (US)
- Max Planck Institute for Astronomy (DE)
- Joint Space Science Institute (US)
- Université Bourgogne Franche-Comté (FR)
- University of Maryland, College Park (US)
- Université de Strasbourg (FR)
- Ontario College of Art and Design (CA)
- University of Toledo (US)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2026-04-27
- DOI
- https://doi.org/10.3847/1538-4357/ae56e8
- Primary Topic
- Galaxies: Formation, Evolution, Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 0.00