GOALS-JWST: Revealing the Buried Star Clusters in the Luminous Infrared Galaxy VV 114

Abstract

We present the results of a James Webb Space Telescope NIRCam investigation into the young massive star cluster (YMC) population in the luminous infrared galaxy VV 114. We identify 374 compact YMC candidates with signal-to-noise ratios ≥ 3, 5, and 5 at F150W, F200W, and F356W, respectively. A direct comparison with our HST cluster catalog reveals that ∼20% of these sources are undetected at optical wavelengths. Based on yggdrasil stellar population models, we identify 17 YMC candidates in our JWST imaging alone with F150W – F200W and F200W – F356W colors suggesting they are all very young, dusty (A_V = 5–15), and massive (10^(5.8) < M_⊙ < 6.1). The discovery of these "hidden" sources, many of which are found in the "overlap" region between the two nuclei, quadruples the number of t < Myr clusters and nearly doubles the number of t < 6 Myr clusters detected in VV 114. Now extending the cluster age distribution (dN/dτ ∝ τ^γ ) to the youngest ages, we find a slope of γ = −1.30 ± 0.39 for 10⁶ < τ(yr) < 10⁷, which is consistent with the previously determined value from 10⁷ < τ(yr) < 10^(8.5), and confirms that VV 114 has a steep age distribution slope for all massive star clusters across the entire range of cluster ages observed. Finally, the consistency between our JWST- and HST-derived age distribution slopes indicates that the balance between cluster formation and destruction has not been significantly altered in VV 114 over the last 0.5 Gyr.

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