FEAST: Probing hierarchical star formation with the spatial distributions of young star clusters

Buckner, Anne 2026. FEAST: Probing hierarchical star formation with the spatial distributions of young star clusters. The Astrophysical Journal 999 (2) , 189. 10.3847/1538-4357/ae3a92

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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 D2 values of the YSCs’ underlying distributions are calculated from model fits to the TPCFs. Our values of D2 derived from the youngest YSC populations align better with the expected value of D2 ∼ 1.3 for a universal star formation process compared to previous findings.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Physics and Astronomy
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Type: cc-by
Publisher:	American Astronomical Society
ISSN:	0004-637X
Date of First Compliant Deposit:	9 March 2026
Date of Acceptance:	15 January 2026
Last Modified:	09 Mar 2026 11:30
URI:	https://orca.cardiff.ac.uk/id/eprint/185592

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