Globular Clusters in the Galaxy Cluster MACS0416 at z = 0.397

Jessica M. Berkheimer; Rogier A. Windhorst; William E. Harris; Anton M. Koekemoer; Timothy Carleton; Seth H. Cohen; Rolf A. Jansen; Dan Coe; Jose Diego; Christopher J. Conselice; Simon P. Driver; Brenda L. Frye; Norman A. Grogin; Kate Hartman; Tyler R. Hinrichs; Benne W. Holwerda; Patrick S. Kamieneski; Kaitlyn E. Keatley; William C. Keel; Ray A. Lucas; Madeline A. Marshall; Mario Nonino; Nor Pirzkal; Massimo Ricotti; Clayton D. Robertson; Aaron Robotham; Russell E. Ryan, Jr.; Jake Summers; Christopher N. A. Willmer; Haojing Yan

arXiv · 2508.03883

Globular Clusters in the Galaxy Cluster MACS0416 at z = 0.397

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Abstract

We present a photometric analysis of globular clusters (GCs) in the massive galaxy cluster MACS J0416.1-2403 (z = 0.397) using deep JWST/NIRCam imaging from the PEARLS program. PSF photometry was performed in the short wavelength filters F090W, F115W, F150W, and F200W, yielding a catalog of approximately 3 x 10^3 unresolved, point-like sources consistent with a GC population. Artificial star tests indicate 80% completeness at F200W = 30.36 mag. The color-magnitude diagrams show a narrow GC sequence well reproduced by PARSEC single-stellar-population models spanning ages of 5-9 Gyr and metallicities from [M/H] = -2.0 to +0.2, consistent with evolved GC systems at this redshift. The globular cluster luminosity function (GCLF) follows a log-normal form truncated by incompleteness at the faint end. The brightest sources extend slightly beyond the locus of classical GCs, suggesting a small number of UCD-like systems or stripped nuclei, while the bulk of the population exhibits the luminosities and colors expected for mature globular clusters at z ~ 0.4.

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Jessica M. Berkheimer, Rogier A. Windhorst, William E. Harris, Anton M. Koekemoer, Timothy Carleton, Seth H. Cohen, Rolf A. Jansen, Dan Coe, Jose Diego, Christopher J. Conselice, Simon P. Driver, Brenda L. Frye, Norman A. Grogin, Kate Hartman, Tyler R. Hinrichs, Benne W. Holwerda, Patrick S. Kamieneski, Kaitlyn E. Keatley, William C. Keel, Ray A. Lucas, Madeline A. Marshall, Mario Nonino, Nor Pirzkal, Massimo Ricotti, Clayton D. Robertson, Aaron Robotham, Russell E. Ryan, Jr., Jake Summers, Christopher N. A. Willmer, Haojing Yan. 2025-08-05. Globular Clusters in the Galaxy Cluster MACS0416 at z = 0.397. https://arxiv.org/abs/2508.03883

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