Physically Motivated Stellar Populations for Galaxies at Cosmic Dawn with a Temperature-Dependent IMF
Abstract
The first few years of James Webb Space Telescope observations have identified previously undetected galaxies at z>12 and provided new constraints on galaxies at z>8. Many of these objects have stellar masses that are difficult to reconcile with ΛCDM, inferred from models not calibrated for the high-redshift Universe. This necessitates new, more astrophysically plausible stellar population models for estimating stellar masses of galaxies at cosmic dawn. We introduce a simple stellar population (SSP) library, Simple Stellar Populations with Temperature (SSPT), computed using a temperature-dependent stellar initial mass function and its implementation in the public code CIGALE. When used in a configuration designed for high-redshift galaxies that requires young stellar population ages, the new models predict stellar masses that are ~0.3-0.5 dex lower than estimates from similar CIGALE analyses using models calibrated to the local Universe, and nearly 2 dex lower than estimates from analyses using other codes and softer constraints on stellar ages. Application of these physically motivated stellar populations suggests that stellar masses of early star-forming galaxies are not in tension with ΛCDM, and that galaxy formation from virialized halos remains a reasonable hypothesis at the highest redshifts. The SSPT SSPs and their CIGALE implementation are released publicly.
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BibTeX
@misc{bowling2026physically,
title = {{Physically Motivated Stellar Populations for Galaxies at Cosmic Dawn with a Temperature-Dependent IMF}},
author = {Gibson B. Bowling and Charles L. Steinhardt and Lachlan J. Hobart and Carter Meyerhoff and Jackson Headon and Christopher Cain and Timothy Carleton and Kevin S. Croker and Hunter D. Sparks and Maria J. Sanchez Rincon and Maksymilian T. Malinski and Zachary Borowiak and Caleb S. Watson and Rafael Ortiz III and Rogier A. Windhorst and Rolf A. Jansen and Seth H. Cohen and Tanish Parida},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.01595},
eprint = {2611.01595},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.01595},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Physically Motivated Stellar Populations for Galaxies at Cosmic Dawn with a Temperature-Dependent IMF
AU - Gibson B. Bowling
AU - Charles L. Steinhardt
AU - Lachlan J. Hobart
AU - Carter Meyerhoff
AU - Jackson Headon
AU - Christopher Cain
AU - Timothy Carleton
AU - Kevin S. Croker
AU - Hunter D. Sparks
AU - Maria J. Sanchez Rincon
AU - Maksymilian T. Malinski
AU - Zachary Borowiak
AU - Caleb S. Watson
AU - Rafael Ortiz III
AU - Rogier A. Windhorst
AU - Rolf A. Jansen
AU - Seth H. Cohen
AU - Tanish Parida
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.01595
UR - https://arxiv.org/abs/2611.01595
AB - The first few years of James Webb Space Telescope observations have identified previously undetected galaxies at z>12 and provided new constraints on galaxies at z>8. Many of these objects have stellar masses that are difficult to reconcile with ΛCDM, inferred from models not calibrated for the high-redshift Universe. This necessitates new, more astrophysically plausible stellar population models for estimating stellar masses of galaxies at cosmic dawn. We introduce a simple stellar population (SSP) library, Simple Stellar Populations with Temperature (SSPT), computed using a temperature-dependent stellar initial mass function and its implementation in the public code CIGALE. When used in a configuration designed for high-redshift galaxies that requires young stellar population ages, the new models predict stellar masses that are ~0.3-0.5 dex lower than estimates from similar CIGALE analyses using models calibrated to the local Universe, and nearly 2 dex lower than estimates from analyses using other codes and softer constraints on stellar ages. Application of these physically motivated stellar populations suggests that stellar masses of early star-forming galaxies are not in tension with ΛCDM, and that galaxy formation from virialized halos remains a reasonable hypothesis at the highest redshifts. The SSPT SSPs and their CIGALE implementation are released publicly.
ER -