Globular Clusters in the Galaxy Cluster MACS0416 at z = 0.397
/ Authors
Jessica M. Berkheimer, R. Windhorst, W. Harris, A. Koekemoer, T. Carleton, S. Cohen, R. Jansen, D. Coe, J. Diego, C. Conselice
and 20 more authors
S. Driver, B. Frye, N. Grogin, Kate Hartman, Tyler Hinrichs, B. Holwerda, P. Kamieneski, Kaitlyn E. Keatley, W. Keel, R. Lucas, M. Marshall, M. Nonino, N. Pirzkal, M. Ricotti, C. Robertson, A. Robotham, R. Ryan, J. Summers, C. Willmer, Haojing Yan
/ 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. Point-spread function photometry was performed in the short wavelength filters, F090W, F115W, F150W, and F200W, yielding a catalog of ∼3 × 103 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 GC luminosity function 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 ultracompact dwarf-like systems or stripped nuclei, while the bulk of the population exhibits the luminosities and colors expected for mature GCs at z ≃ 0.4.
Journal: The Astronomical Journal