Fraction of stars in clusters for the LEGUS dwarf galaxies

Creators: Cook, D. O.; Lee, J. C.; Adamo, A.; Calzetti, D.; Chandar, R.; Whitmore, B. C.; Aloisi, A.; Cignoni, M.; Dale, D. A.; Elmegreen, B. G.; Fumagalli, M.; Grasha, K.; Johnson, K. E.; Kennicutt, R. C.; Kim, H.; Linden, S. T.; Messa, M.; Östlin, G.; Ryon, J. E.; Sacchi, E.; Thilker, D. A.; Tosi, M.; Wofford, A.

Abstract

We study the young star cluster populations in 23 dwarf and irregular galaxies observed by the Hubble Space Telescope (HST) Legacy ExtraGalactic Ultraviolet Survey (LEGUS), and examine relationships between the ensemble properties of the cluster populations and those of their host galaxies: star formation rate (SFR) density (Σ_(SFR)). A strength of this analysis is the availability of SFRs measured from temporally resolved star formation histories that provide the means to match cluster and host galaxy properties on several time-scales (1–10, 1–100, and 10–100 Myr). Nevertheless, studies of this kind are challenging for dwarf galaxies due to the small numbers of clusters in each system. We mitigate these issues by combining the clusters across different galaxies with similar Σ_(SFR) properties. We find good agreement with a well-established relationship (M_V^(brightest)–SFR), but find no significant correlations between Σ_(SFR) and the slopes of the cluster luminosity function, mass function, nor the age distribution. We also find no significant trend between the fraction of stars in bound clusters at different age ranges (Γ₁₋₁₀, Γ₁₀₋₁₀₀, and Γ₁₋₁₀₀) and Σ_(SFR) of the host galaxy. Our data show a decrease in Γ over time (from 1–10 to 10–100 Myr) suggesting early cluster dissolution, though the presence of unbound clusters in the youngest time bin makes it difficult to quantify the degree of dissolution. While our data do not exhibit strong correlations between Σ_(SFR) and ensemble cluster properties, we cannot rule out that a weak trend might exist given the relatively large uncertainties due to low number statistics and the limited Σ_(SFR) range probed.

Additional Information

© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) This study is based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program #13364. This research has made use of the NASA/IPAC Extragalactic Database (NED) that is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. AAd acknowledges the support of the Swedish Research Council (Vetenskapsradet) and the Swedish National Space Board (SNSB). MF acknowledges support from the European Research Council (ERC) under the European Union's Horizon 2020 Framework Programme (grant agreement no. 757535). DATA AVAILABILITY. The LEGUS star cluster catalogues are available at https://legus.stsci.edu/ or can be requested by contacting the author. The galaxy properties and Γ measurements are available upon request.

Attached Files

Published - stac3748.pdf

Files

stac3748.pdf

Files (3.8 MB)

Name	Size	Download all
stac3748.pdf md5:f1925592797005c0882f6132740c3aca	3.8 MB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes