Star Cluster Populations in 38 Spiral Galaxies: Evidence for Near-Universal Mass and Age Distributions from PHANGS
Abstract
We present the largest study to date of star cluster mass and age distributions in nearby galaxies. The analysis is based on a uniformly selected catalog of over 15,000 (36,000) human (machine) classified compact clusters across 38 spiral galaxies in the PHANGS-HST survey, with improved photometric SED age dating that mitigates key degeneracies with reddening and metallicity. The galaxies span a factor of ~100 in star formation rate (SFR) and in their surface density of star formation and molecular gas (Sigma_SFR, Sigma_H2), and cover a broad range of morphologies. We find that cluster mass functions are well described by a power law, dN/dM ~ M^beta, with beta=-1.9 +/- 0.2, and that this shape is remarkably similar across all galaxies in our sample and eight composite groups of galaxies with similar SFRs, with no significant dependence on SFR, Sigma_SFR}, or Sigma_H2. Cluster age distributions decline steeply and can be described by dN/dt ~ t^gamma with gamma=-0.83 +/- 0.24, again with little dependence on host-galaxy properties or cluster mass. The independence of the mass and age distributions implies a separable joint distribution, g(M,t) ~ M^beta t^gamma, and suggests that cluster populations in spiral disks are dominated by strong, mass-independent dissolution over their first ~Gyr. These results establish a benchmark for interpreting cluster demographics across diverse galactic environments and provide context for studies of young cluster populations at high redshift.
Versions
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BibTeX
@misc{chandar2026star,
title = {{Star Cluster Populations in 38 Spiral Galaxies: Evidence for Near-Universal Mass and Age Distributions from PHANGS}},
author = {Rupali Chandar and Matthew R. Floyd and David A. Thilker and Kiana Henny and Bradley C. Whitmore and Janice C. Lee and Sinan Deger and Daniel A. Dale and Kirsten L. Larson and Mederic Bouquien and Oleg Gredin and Daniel Maschmann and Adam K. Leroy and Erk Rosolowsky and Leonardo Ubeda and Ashley T. Barnes and Eva Schinnerer and Eric Emsellem and Angus Mok and Kathryn Grasha and Francesca Pinna and Aida Wofford and Ralf S. Klessen and Simon Glover and Sumit K. Sarbadhicary and Ivan Gerasimov},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.02606},
eprint = {2610.02606},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.02606},
}
RIS
TY - UNPB
TI - Star Cluster Populations in 38 Spiral Galaxies: Evidence for Near-Universal Mass and Age Distributions from PHANGS
AU - Rupali Chandar
AU - Matthew R. Floyd
AU - David A. Thilker
AU - Kiana Henny
AU - Bradley C. Whitmore
AU - Janice C. Lee
AU - Sinan Deger
AU - Daniel A. Dale
AU - Kirsten L. Larson
AU - Mederic Bouquien
AU - Oleg Gredin
AU - Daniel Maschmann
AU - Adam K. Leroy
AU - Erk Rosolowsky
AU - Leonardo Ubeda
AU - Ashley T. Barnes
AU - Eva Schinnerer
AU - Eric Emsellem
AU - Angus Mok
AU - Kathryn Grasha
AU - Francesca Pinna
AU - Aida Wofford
AU - Ralf S. Klessen
AU - Simon Glover
AU - Sumit K. Sarbadhicary
AU - Ivan Gerasimov
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.02606
UR - https://arxiv.org/abs/2610.02606
AB - We present the largest study to date of star cluster mass and age distributions in nearby galaxies. The analysis is based on a uniformly selected catalog of over 15,000 (36,000) human (machine) classified compact clusters across 38 spiral galaxies in the PHANGS-HST survey, with improved photometric SED age dating that mitigates key degeneracies with reddening and metallicity. The galaxies span a factor of ~100 in star formation rate (SFR) and in their surface density of star formation and molecular gas (Sigma_SFR, Sigma_H2), and cover a broad range of morphologies. We find that cluster mass functions are well described by a power law, dN/dM ~ M^beta, with beta=-1.9 +/- 0.2, and that this shape is remarkably similar across all galaxies in our sample and eight composite groups of galaxies with similar SFRs, with no significant dependence on SFR, Sigma_SFR}, or Sigma_H2. Cluster age distributions decline steeply and can be described by dN/dt ~ t^gamma with gamma=-0.83 +/- 0.24, again with little dependence on host-galaxy properties or cluster mass. The independence of the mass and age distributions implies a separable joint distribution, g(M,t) ~ M^beta t^gamma, and suggests that cluster populations in spiral disks are dominated by strong, mass-independent dissolution over their first ~Gyr. These results establish a benchmark for interpreting cluster demographics across diverse galactic environments and provide context for studies of young cluster populations at high redshift.
ER -