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arXiv · 2610.35249

Reconstructing the Three-Dimensional Stellar Mass Profiles of Massive Galaxy Clusters

Jong-In Park·Jubee Sohn·I-Non Chiu
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Abstract

We investigate the three-dimensional (3D) stellar mass profiles of galaxy clusters using simulations and observations. We develop the Projection-to-Enclosed Estimator by Layers (PEEL) model, which geometrically reconstructs the 3D stellar mass profile from the projected stellar mass profile under the assumption of spherical symmetry. Starting from the outermost annulus, the PEEL model subtracts the contributions of the outer shells from the projected mass in each inner annulus. Using 205 halos from the TNG-Cluster simulation, we show that the reconstructed profile (hereafter the PEEL profile) recovers the true 3D stellar mass profile without systematic bias. We also examine potential systematic effects, including the use of subhalos versus stellar particles, the choice of cluster center, and the 3D shape of the halo. We then apply the PEEL model to a stacked sample of nine massive clusters from the MAssive Cluster survey with Hectospec (MACH). The observed PEEL profile is much flatter than the simulated 3D profile, indicating that the simulated clusters have a more centrally concentrated stellar mass distribution, mainly because of an excess of extremely massive galaxies in their cores. Combining the PEEL profile with the total mass profile from the caustic technique, we derive the stellar mass fraction profile of the observed clusters. The stellar mass fraction remains nearly constant at $0.009 \pm 0.002$ within $R_{200}$, consistent with previous observations and with the simulated clusters. The PEEL model provides a practical tool for measuring the 3D stellar mass profiles of large cluster samples from future wide-field spectroscopic surveys.

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Jong-In Park, Jubee Sohn, I-Non Chiu. 2026-10-26. Reconstructing the Three-Dimensional Stellar Mass Profiles of Massive Galaxy Clusters. https://arxiv.org/abs/2610.35249

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