GOALS-JWST: Revealing the Buried Star Clusters in the Luminous Infrared Galaxy VV 114
Sean T. Linden, A. Evans, L. Armus, J. Rich, Kirsten L. Larson, Thomas S. -Y. Lai, George C. Privon, U Vivian, Hanae Inami, Thomas Bohn, Yiqing Song, Loreto Barcos-Muñoz, V. Charmandaris, Anne M. Medling, Sabrina Stierwalt, T. Díaz-Santos, Torsten Böker, P. van der Werf, S. Aalto, P. N. Appleton, M. J. I. Brown, Christopher C. Hayward, Justin Howell, K. Iwasawa, F. Kemper, D. T. Frayer, David R. Law, Matthew A. Malkan, J. A. Marshall, J. M. Mazzarella, E. J. Murphy, D. B. Sanders, J. Surace
Abstract
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 ⊙ < 10 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 < 3 Myr clusters and nearly doubles the number of t < 6 Myr clusters detected in VV 114. Now extending the cluster age distribution ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic">dN</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>d</mml:mi> <mml:mi>τ</mml:mi> <mml:mo>∝</mml:mo> <mml:msup> <mml:mrow> <mml:mi>τ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>γ</mml:mi> </mml:mrow> </mml:msup> </mml:math> ) to the youngest ages, we find a slope of γ = −1.30 ± 0.39 for 10 6 < τ (yr) < 10 7 , which is consistent with the previously determined value from 10 7 < 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.