The Atacama Cosmology Telescope: stellar mass growth in massive galaxy clusters from DR5 over the past 7 billion years

Document Type

Journal Article

Role

Author

Published In

Monthly Notices of the Royal Astronomical Society

Volume

549

Issue

2

Article Number

stag778

Publication Date

4-23-2026

Abstract

We probe the stellar mass growth in a sample of 568 Sunyaev–Zel’dovich (SZ) selected galaxy clusters with masses greater than  and redshifts in the range ⁠, drawn from the fifth data release of the Atacama Cosmology Telescope (ACT DR5). By utilizing deep photometry from the tenth data release of the Dark Energy Camera Legacy Survey (DECaLS DR10), we construct redshift- and cluster mass-binned composite cluster stellar mass functions (SMFs), down to ⁠. This work presents the first analysis of the cluster SMF for this cluster sample at this epoch. We find that the characteristic stellar mass (⁠⁠) of the cluster SMF evolves marginally from ⁠, with most of the measurable growth occurring at ⁠. This suggests that most of the massive galaxy population in clusters (⁠⁠) is largely established by ⁠, with subsequent evolution driven by late-time assembly processes. The low-mass slope (⁠⁠) of the composite cluster SMF is flat at high-z (⁠⁠) but steepens at ⁠, suggesting an abundance of massive galaxies in high-z clusters compared to low-z clusters. We measure the evolution of cluster stellar mass fractions contained within galaxies with  between ⁠, and find evidence of significant growth, by a factor of 2.5, after accounting for the growth in cluster halo mass over this epoch.

Keywords

galaxies: clusters: general, galaxies: evolution, galaxies: formation, galaxies: luminosity function, mass function, galaxies: photometry, galaxies: stellar content

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