Halo Mass Function Constraints on Early Galaxy and AGN Populations in the JWST Era
Abstract
The discovery by the James Webb Space Telescope (JWST) of massive galaxies and luminous active galactic nuclei (AGN) at high redshift provides an increasingly sensitive test of the connection between cosmological structure formation and the astrophysical processes that make dark matter halos observable. We develop a framework connecting the linear matter power spectrum to the mass variance, peak height, halo mass function (HMF), cumulative halo abundance, and observable galaxy and AGN populations. We use the Sheth-Tormen (ST) HMF as the baseline and compare it with an illustrative Bolshoi-Klypin-calibrated modification (KST) to quantify the sensitivity of predictions to the calibration of the HMF against cosmological N-body simulations. We apply the framework to three complementary tests: the baryonic and stellar mass reservoir available to massive galaxies, the abundance of halos capable of hosting luminous AGN, and the rest frame ultraviolet luminosity function of high redshift galaxies. Because the most massive systems occupy the rare, high peak tail of the halo distribution, modest changes in inferred host mass, baryonic conversion efficiency, black-hole occupation or duty cycle, and HMF calibration can produce large changes in predicted abundances. The ST-KST comparison shows that uncertainty in the high redshift halo population can materially affect the inferred host supply, particularly toward large z (10). Comparison with representative JWST massive galaxy, AGN, and UV luminosity function measurements demonstrates that matching the properties of an individual source is not sufficient for population consistency; the corresponding host halos must also exist in adequate numbers. Current observations provide increasingly stringent quantitative stress tests of both cosmological halo abundances and the baryonic and black hole physics at cosmic dawn.
Related
- Constraints on the magnetic field in the hadronic scenario for the origin of the radio halo in the A1795 galaxy cluster
- From Quantum Field Fluctuations to High-Redshift AGN: Semiclassical Origins of Halo Mass Function Constraints in the JWST Era
- AMICO galaxy clusters in KiDS-1000: Cosmological constraints from the two-point correlation function
- The Deep Learning Halo Definer: A Multimodal Framework for Halo Mass and Gas Fraction Inference on Galaxy Groups and Clusters
- A Graph Attention Network Framework for Simultaneous Prediction of Galaxy and Dark Matter Halo Properties in GAMA DR4
BibTeX
@misc{yogeswaren2026halo,
title = {{Halo Mass Function Constraints on Early Galaxy and AGN Populations in the JWST Era}},
author = {Elan Yogeswaren and Robert Schaefer},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.08731},
eprint = {2610.08731},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.08731},
note = {CC BY-SA 4.0},
}
RIS
TY - UNPB
TI - Halo Mass Function Constraints on Early Galaxy and AGN Populations in the JWST Era
AU - Elan Yogeswaren
AU - Robert Schaefer
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2610.08731
UR - https://arxiv.org/abs/2610.08731
AB - The discovery by the James Webb Space Telescope (JWST) of massive galaxies and luminous active galactic nuclei (AGN) at high redshift provides an increasingly sensitive test of the connection between cosmological structure formation and the astrophysical processes that make dark matter halos observable. We develop a framework connecting the linear matter power spectrum to the mass variance, peak height, halo mass function (HMF), cumulative halo abundance, and observable galaxy and AGN populations. We use the Sheth-Tormen (ST) HMF as the baseline and compare it with an illustrative Bolshoi-Klypin-calibrated modification (KST) to quantify the sensitivity of predictions to the calibration of the HMF against cosmological N-body simulations. We apply the framework to three complementary tests: the baryonic and stellar mass reservoir available to massive galaxies, the abundance of halos capable of hosting luminous AGN, and the rest frame ultraviolet luminosity function of high redshift galaxies. Because the most massive systems occupy the rare, high peak tail of the halo distribution, modest changes in inferred host mass, baryonic conversion efficiency, black-hole occupation or duty cycle, and HMF calibration can produce large changes in predicted abundances. The ST-KST comparison shows that uncertainty in the high redshift halo population can materially affect the inferred host supply, particularly toward large z (10). Comparison with representative JWST massive galaxy, AGN, and UV luminosity function measurements demonstrates that matching the properties of an individual source is not sufficient for population consistency; the corresponding host halos must also exist in adequate numbers. Current observations provide increasingly stringent quantitative stress tests of both cosmological halo abundances and the baryonic and black hole physics at cosmic dawn.
ER -