Where Galaxies Go to Die: The Environments of Massive Quiescent Galaxies at $3<z<5$

Ian McConachie; Anna de Graaff; Michael V. Maseda; Joel Leja; Yunchong Zhang; David J. Setton; Rachel Bezanson; Leindert A. Boogaard; Gabriel Brammer; Nikko J. Cleri; Olivia R. Cooper; Karl Glazebrook; Rashmi Gottumukkala; Jenny E. Greene; Andy D. Goulding; Michaela Hirschmann; Ivo Labbe; Zach Lewis; Jorryt Matthee; Tim B. Miller; Rohan P. Naidu; Pascal A. Oesch; Sedona H. Price; Themiya Nanayakkara; Katherine A. Suess; Bingjie Wang; Katherine E. Whitaker; Christina C. Williams

arXiv · 2510.25024

Where Galaxies Go to Die: The Environments of Massive Quiescent Galaxies at $3<z<5$

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Abstract

At low redshift, massive quiescent galaxies (MQGs) are most frequently found in massive, rich galaxy clusters, but at high redshift the trend is less clear. Here, we present spectroscopic evidence of the effects of environment on the formation and assembly of high-redshift MQGs. We identify 25 (5) $\log (M_*/\mathrm{M_\odot}\geq10.5$ ($10.0\leq\log (M_*/\mathrm{M_\odot}<10.5$) spectroscopically-confirmed quiescent galaxies in the UDS and EGS fields at $3 5$, finding that the masses from the inferred MQG SFHs regularly exceed either observed or simulated high-redshift galaxies, which suggests indicates that mergers and ex-situ star formation play a key role in the mass assembly of MQGs in overdense environments.

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Ian McConachie, Anna de Graaff, Michael V. Maseda, Joel Leja, Yunchong Zhang, David J. Setton, Rachel Bezanson, Leindert A. Boogaard, Gabriel Brammer, Nikko J. Cleri, Olivia R. Cooper, Karl Glazebrook, Rashmi Gottumukkala, Jenny E. Greene, Andy D. Goulding, Michaela Hirschmann, Ivo Labbe, Zach Lewis, Jorryt Matthee, Tim B. Miller, Rohan P. Naidu, Pascal A. Oesch, Sedona H. Price, Themiya Nanayakkara, Katherine A. Suess, Bingjie Wang, Katherine E. Whitaker, Christina C. Williams. 2025-10-28. Where Galaxies Go to Die: The Environments of Massive Quiescent Galaxies at $3<z<5$. https://arxiv.org/abs/2510.25024

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