Abstract
Aims. Currently, the global characteristics and evolution of super star clusters (SSCs) are not well understood, due to the large distances to their host galaxies. We aim to study the population of SSCs in IRAS 17138-1017, a luminous infrared galaxy (LIRG), in terms of age, extinction, mass, and luminosity distribution. Methods. We analyzed imaging data in the near-infrared from the GeMS/GSAOI instrument on the Gemini telescope and generated simulations with the radiative transfer code MontAGN. The extraction of SSCs from the images and their photometry in J, H, and Ks allowed us to derive color-color and color-magnitude diagrams. Comparison with a theoretical stellar evolutionary track gives a first hint into the extinction towards each SSC, as well as their ages, despite some degeneracy between those two quantities. Spectra given by our radiative transfer code MontAGN, which includes dust emission, also provide insightful predictions and comparisons. Results. We detect with a fair degree of confidence 54 SSCs of mKs between 16 mag and 21 mag with a median instrumental uncertainty of 0.05 mag. When plotted on a color–color diagram and a color–magnitude diagram, it appears that most of the sources are very much extinct with respect to an intrinsic theoretical evolutionary track. Once de-reddened, the colors point unambiguously to two distinct and very recent starburst episodes at 2.8 and 4.5 Myr. While the SSCs in the 4.5 Myr starburst are distributed along the spiral arms, the 2.8 Myr SSCs are concentrated in the central region. The luminosity and mass functions present a classical power-law behavior, although with shallower slopes than generally observed in LIRGs. Comparison with radiative transfer simulations shows that, the dust thermal emission and scattered light are negligible and could not explain the few very red SSCs that could not be de-reddened safely.
Highlights
The interaction of galaxies, even if it does not end in merging, generally triggers extreme star formation
To simulate embedded SSCs in the IR, we developed additional features for our three-dimensional radiative transfer code MontAGN (Monte Carlo for Active Galactic Nuclei), which was originally designed for the study of active galatic nucleus (AGN) (Grosset et al 2016, 2018; Marin et al 2016)
The excellent quality of the AO-assisted near-IR images in J, H, and Ks obtained with GeMS on Gemini allows us to identify 54 SSCs in the luminous infrared galaxy (LIRG) IRAS 17138-1017 and to extract their photometry
Summary
The interaction of galaxies, even if it does not end in merging, generally triggers extreme star formation. Found in abundance in (U)LIRGs are very young (
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