FEAST: Probing Hierarchical Star Formation with the Spatial Distributions of Young Star Clusters

Abstract We apply the angular two-point correlation function (TPCF) to the spatial distributions of young star clusters (YSCs) in four nearby star forming galaxies (NGC 628, NGC 4449, M51, and M83) in order to investigate their underlying hierarchical structuring. Using newly constructed catalogs of YSCs in the emerging phase (eYSCs), identified in the infrared with JWST, and optical YSCs detected in archival Hubble Space Telescope data, we compute the TPCFs for various cluster samples and age bins across the four galaxies, as part of the Feedback in Emerging extrAgalactic Star ClusTers (FEAST) program. We find clear evidence of hierarchical structuring, especially in eYSCs and YSCs with ages <10 Myr (referred to as oYSCs), which show similar TPCFs within each galaxy. NGC 628 exhibits a clear distinction between the TPCFs of eYSCs and oYSCs, implying a shorter randomization timescale. In contrast, clusters aged 10–300 Myr exhibit progressively more random spatial distributions, becoming effectively random after ∼100 Myr, consistent with earlier studies. The two-dimensional fractal index D 2 values of the YSCs’ underlying distributions are calculated from model fits to the TPCFs. Our values of D 2 derived from the youngest YSC populations align better with the expected value of D 2 ∼ 1.3 for a universal star formation process compared to previous findings.

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Publication Details

Journal
The Astrophysical Journal
Published
2026-03-03
DOI
https://doi.org/10.3847/1538-4357/ae3a92
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
0.00

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article

FEAST: Probing Hierarchical Star Formation with the Spatial Distributions of Young Star Clusters

Daniela Calzetti, A. Bik, Matteo Correnti, Anne S. M. Buckner et al.
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
article

FEAST: Probing Hierarchical Star Formation with the Spatial Distributions of Young Star Clusters

Daniela Calzetti, A. Bik, Matteo Correnti, Anne S. M. Buckner, Matteo Messa, M. Cignoni, D. M. Elmegreen, S. Linden, Giacomo Bortolini, K. Grasha, K. Roger Johnson, Drew Lapeer, Max Hamilton, Linda J. Smith, Alex Pedrini, Thomas S.-Y. Lai, H. Faustino Vieira, Bruce G. Elmegreen, Göran Östlin, Angela Adamo, E. Sabbi
article en

Abstract

Abstract We apply the angular two-point correlation function (TPCF) to the spatial distributions of young star clusters (YSCs) in four nearby star forming galaxies (NGC 628, NGC 4449, M51, and M83) in order to investigate their underlying hierarchical structuring. Using newly constructed catalogs of YSCs in the emerging phase (eYSCs), identified in the infrared with JWST, and optical YSCs detected in archival Hubble Space Telescope data, we compute the TPCFs for various cluster samples and age bins across the four galaxies, as part of the Feedback in Emerging extrAgalactic Star ClusTers (FEAST) program. We find clear evidence of hierarchical structuring, especially in eYSCs and YSCs with ages <10 Myr (referred to as oYSCs), which show similar TPCFs within each galaxy. NGC 628 exhibits a clear distinction between the TPCFs of eYSCs and oYSCs, implying a shorter randomization timescale. In contrast, clusters aged 10–300 Myr exhibit progressively more random spatial distributions, becoming effectively random after ∼100 Myr, consistent with earlier studies. The two-dimensional fractal index D 2 values of the YSCs’ underlying distributions are calculated from model fits to the TPCFs. Our values of D 2 derived from the youngest YSC populations align better with the expected value of D 2 ∼ 1.3 for a universal star formation process compared to previous findings.

The Astrophysical JournalVol. 999(2)
University of Pisa (IT), Australian National University (AU), California Institute of Technology (US), Vassar College (US), Space Telescope Science Institute (US), University of Arizona (US), Stockholm University (SE), Amherst College (US), University of Massachusetts Amherst (US), Astronomical Observatory of Rome (IT), Agenzia Spaziale Italiana (IT), Katonah Museum of Art (US), Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna (IT), Gemini North Observatory (US), Université Bourgogne Franche-Comté (FR), AlbaNova (SE), NSF NOIRLab (US), Istituto Nazionale di Fisica Nucleare, Sezione di Pisa (IT), Infrared Processing and Analysis Center (US), Osservatorio di Astrofisica e Scienza dello Spazio, University of Virginia (US), Cardiff University (GB), National Institute for Astrophysics (IT)
National Science Foundation, Australian Government, European Commission, Swedish National Space Agency, Ministero dell’Istruzione, dell’Università e della Ricerca, Vetenskapsrådet
Openalex Percentile: Top 37%
Galaxies: Formation, Evolution, Phenomena
DOIOpen Access PDFOpenAlex
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