Star cluster catalogues for the LEGUS dwarf galaxies

Authors

D. O. Cook, California Institute of Technology
J. C. Lee, Infrared Processing & Analysis Center
A. Adamo, Stockholms universitet
H. Kim, Gemini Observatory
R. Chandar, The University of Toledo
B. C. Whitmore, Space Telescope Science Institute
A. Mok, The University of Toledo
J. E. Ryon, Space Telescope Science Institute
D. A. Dale, University of Wyoming
D. Calzetti, University of Massachusetts Amherst
J. E. Andrews, The University of Arizona
A. Aloisi, Space Telescope Science Institute
G. Ashworth, Durham University
S. N. Bright, Space Telescope Science Institute
T. M. Brown, Space Telescope Science Institute
C. Christian, Space Telescope Science Institute
M. Cignoni, Università di Pisa
G. C. Clayton, Louisiana State University
R. Da Silva, University of California, Santa Cruz
S. E. De Mink, Astronomical Institute Anton Pannekoek
C. L. Dobbs, University of Exeter
B. G. Elmegreen, IBM Thomas J. Watson Research Center
D. M. Elmegreen, Vassar College
A. S. Evans, University of Virginia
M. Fumagalli, Durham University
J. S. Gallagher, University of Wisconsin-Madison
D. A. Gouliermis, Universität Heidelberg
K. Grasha, University of Massachusetts Amherst
E. K. Grebel, Astronomisches Rechen-Institut Heidelberg
A. Herrero, Instituto Astrofisico de Canarias
D. A. Hunter, Lowell Observatory
E. I. Jensen, University of Wyoming
K. E. Johnson, University of Virginia

Document Type

Article

Publication Date

4-21-2019

Abstract

We present the star cluster catalogues for 17 dwarf and irregular galaxies in the HST Treasury Program 'Legacy ExtraGalactic UV Survey' (LEGUS). Cluster identification and photometry in this sub-sample are similar to that of the entire LEGUS sample, but special methods were developed to provide robust catalogues with accurate fluxes due to low cluster statistics. The colours and ages are largely consistent for two widely used aperture corrections, but a significant fraction of the clusters are more compact than the average training cluster. However, the ensemble luminosity, mass, and age distributions are consistent suggesting that the systematics between the two methods are less than the random errors. When compared with the clusters from previous dwarf galaxy samples, we find that the LEGUS catalogues are more complete and provide more accurate total fluxes. Combining all clusters into a composite dwarf galaxy, we find that the luminosity and mass functions can be described by a power law with the canonical index of '2 independent of age and global SFR binning. The age distribution declines as a power law, with an index of ' 0.80 ± 0.15, independent of cluster mass and global SFR binning. This decline of clusters is dominated by cluster disruption since the combined star formation histories and integrated-light SFRs are both approximately constant over the last few hundred Myr. Finally, we find little evidence for an upper-mass cut-off (<2σ) in the composite cluster mass function, and can rule out a truncation mass below 10 4.5 M but cannot rule out the existence of a truncation at higher masses.

Publication Source (Journal or Book title)

Monthly Notices of the Royal Astronomical Society

First Page

4897

Last Page

4919

Recommended Citation

Cook, D., Lee, J., Adamo, A., Kim, H., Chandar, R., Whitmore, B., Mok, A., Ryon, J., Dale, D., Calzetti, D., Andrews, J., Aloisi, A., Ashworth, G., Bright, S., Brown, T., Christian, C., Cignoni, M., Clayton, G., Da Silva, R., De Mink, S., Dobbs, C., Elmegreen, B., Elmegreen, D., Evans, A., Fumagalli, M., Gallagher, J., Gouliermis, D., Grasha, K., Grebel, E., Herrero, A., Hunter, D., Jensen, E., & Johnson, K. (2019). Star cluster catalogues for the LEGUS dwarf galaxies. Monthly Notices of the Royal Astronomical Society, 484 (4), 4897-4919. https://doi.org/10.1093/mnras/stz331