Dwarf Galaxies at Cosmic Noon: New JWST Constraints on Satellite Models and Subhalo Tidal Evolution

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Main Authors: Wan, Jenny T., Mansfield, Philip, Suess, Katherine A., Wang, Yunchong, Yuan, Sihan, Williams, Christina C., Wechsler, Risa H.
Format: Preprint
Published: 2025
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author Wan, Jenny T.
Mansfield, Philip
Suess, Katherine A.
Wang, Yunchong
Yuan, Sihan
Williams, Christina C.
Wechsler, Risa H.
author_facet Wan, Jenny T.
Mansfield, Philip
Suess, Katherine A.
Wang, Yunchong
Yuan, Sihan
Williams, Christina C.
Wechsler, Risa H.
contents The advent of JWST has revolutionized the study of faint satellite galaxies at $z \gtrsim 1$, enabling statistical constraints on galaxy evolution and the galaxy$-$halo connection in a previously unexplored mass and redshift regime. We compare satellite abundances at $1 < z < 3.5$ from recent JWST observations with predictions from cosmological dark matter-only zoom-in simulations. We identify and quantify several sources of biases that can impact theoretical satellite counts, finding that assumptions about subhalo tidal evolution introduce the largest uncertainty in predictions for the satellite mass function. Using a flexible galaxy disruption model, we explore a range of disruption scenarios, spanning hydrodynamically motivated and idealized prescriptions, to bracket plausible physical outcomes. We show that varying galaxy durability can change the predicted satellite mass functions by a factor of $\sim3.5$. The JWST data and our fiducial model are consistent within $1-2σ$ across the full redshift ($1 < z < 3.5$) and stellar mass ($M_\star> 10^7~\mathrm{M}_\odot$) range probed. We find evidence that subhalos are at least as long-lived as predicted by hydrodynamic simulations. Our framework will enable robust constraints on the tidal evolution of subhalos with future observations. This work presents the first direct comparison between cosmological models and observations of the high-redshift satellite population in this low-mass regime. These results showcase JWST's emerging power to test structure formation in the first half of the Universe in a new domain and to constrain the physical processes driving the evolution of low-mass galaxies across cosmic time.
format Preprint
id arxiv_https___arxiv_org_abs_2507_13448
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dwarf Galaxies at Cosmic Noon: New JWST Constraints on Satellite Models and Subhalo Tidal Evolution
Wan, Jenny T.
Mansfield, Philip
Suess, Katherine A.
Wang, Yunchong
Yuan, Sihan
Williams, Christina C.
Wechsler, Risa H.
Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
The advent of JWST has revolutionized the study of faint satellite galaxies at $z \gtrsim 1$, enabling statistical constraints on galaxy evolution and the galaxy$-$halo connection in a previously unexplored mass and redshift regime. We compare satellite abundances at $1 < z < 3.5$ from recent JWST observations with predictions from cosmological dark matter-only zoom-in simulations. We identify and quantify several sources of biases that can impact theoretical satellite counts, finding that assumptions about subhalo tidal evolution introduce the largest uncertainty in predictions for the satellite mass function. Using a flexible galaxy disruption model, we explore a range of disruption scenarios, spanning hydrodynamically motivated and idealized prescriptions, to bracket plausible physical outcomes. We show that varying galaxy durability can change the predicted satellite mass functions by a factor of $\sim3.5$. The JWST data and our fiducial model are consistent within $1-2σ$ across the full redshift ($1 < z < 3.5$) and stellar mass ($M_\star> 10^7~\mathrm{M}_\odot$) range probed. We find evidence that subhalos are at least as long-lived as predicted by hydrodynamic simulations. Our framework will enable robust constraints on the tidal evolution of subhalos with future observations. This work presents the first direct comparison between cosmological models and observations of the high-redshift satellite population in this low-mass regime. These results showcase JWST's emerging power to test structure formation in the first half of the Universe in a new domain and to constrain the physical processes driving the evolution of low-mass galaxies across cosmic time.
title Dwarf Galaxies at Cosmic Noon: New JWST Constraints on Satellite Models and Subhalo Tidal Evolution
topic Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2507.13448