Reconciling the Fundamental Plane of Early-Type Galaxies with hydrodynamical simulations: The case of IllustrisTNG100-1
6 affiliations
- 1Federal University of Sergipe Physics Department, , 49100-000, São Cristovão-SE ,
- 2University Federico II Department of Physics E. Pancini, , Via Cinthia 21, I-80126, Naples ,
- 3Scuola Superiore Meridionale, Via Mezzocannone , 4, 80138, Naples ,
- 4INAF - Osservatorio Astronomico di Capodimonte , Salita Moiariello 16, I-80131 Napoli ,
- 5Center for Computational Astrophysics, Flatiron Institute , 162 5th Avenue, New York, NY, 10010 ,
- 6Princeton University Department of Astrophysical Sciences, , 4 Ivy Lane, Princeton, NJ 08544
Abstract
The Fundamental Plane (FP) of Early-Type Galaxies (ETGs) encapsulates a tight correlation among their structural and dynamical properties and provides an important benchmark for galaxy formation models. However, cosmological hydrodynamical simulations have historically struggled to reproduce the observed FP tilt, with discrepancies often attributed to flawed feedback physics or insufficient resolution. Using the IllustrisTNG100-1 simulation, we show that adopting observationally motivated measurements, including Sérsic-derived photometric parameters and dynamically inferred velocity dispersions designed to minimise softening-length effects, substantially reduces the discrepancy between simulated and observed FPs. We further explore the impact of non-universal, mass-dependent Initial Mass Function (IMF) variations through forward modelling of their effects on galaxy structural and dynamical quantities. In particular, within the adopted r-band framework, bottom-heavy IMF variations bring the mean FP coefficients into close agreement with observational constraints for both direct and orthogonal fits, while the simulated FP remains thinner than the observed relation. Our results suggest that a significant fraction of the long-standing FP tension arises from how galaxy observables are extracted and interpreted in simulations, although residual discrepancies may still reflect limitations in the underlying baryonic physics. These findings highlight the importance of observational realism and IMF variations for interpreting galaxy scaling relations and for improving the predictive power of hydrodynamical simulations of ETG formation.
Related
- Dark matter haloes from dwarf to massive galaxies: no systematic inner-density tension with ΛCDM hydrodynamical simulations
- [CII] as a global cold gas tracer in novel hydrodynamical simulations
- Dark matter density profiles of the Milky Way satellite population: Reconciling simulations and observations
- Impact of rotation on the amplitude of acoustic modes in solar-like stars: insights from hydrodynamical simulations
- specwizard: A Public Python Framework for Creating Synthetic Absorption Spectra from Hydrodynamical Simulations
BibTeX
@article{ferreira2026reconciling,
title = {{Reconciling the Fundamental Plane of Early-Type Galaxies with hydrodynamical simulations: The case of IllustrisTNG100-1}},
author = {Pedro de Araujo Ferreira and Nicola R Napolitano and Crescenzo Tortora and Luciano Casarini and Francisco Villaescusa-Navarro},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
month = oct,
doi = {10.1093/mnras/stag2081},
url = {https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2081/9005958},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Reconciling the Fundamental Plane of Early-Type Galaxies with hydrodynamical simulations: The case of IllustrisTNG100-1
AU - Pedro de Araujo Ferreira
AU - Nicola R Napolitano
AU - Crescenzo Tortora
AU - Luciano Casarini
AU - Francisco Villaescusa-Navarro
PY - 2026
DA - 2026/10/31
JO - Monthly Notices of the Royal Astronomical Society
DO - 10.1093/mnras/stag2081
UR - https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stag2081/9005958
AB - The Fundamental Plane (FP) of Early-Type Galaxies (ETGs) encapsulates a tight correlation among their structural and dynamical properties and provides an important benchmark for galaxy formation models. However, cosmological hydrodynamical simulations have historically struggled to reproduce the observed FP tilt, with discrepancies often attributed to flawed feedback physics or insufficient resolution. Using the IllustrisTNG100-1 simulation, we show that adopting observationally motivated measurements, including Sérsic-derived photometric parameters and dynamically inferred velocity dispersions designed to minimise softening-length effects, substantially reduces the discrepancy between simulated and observed FPs. We further explore the impact of non-universal, mass-dependent Initial Mass Function (IMF) variations through forward modelling of their effects on galaxy structural and dynamical quantities. In particular, within the adopted r-band framework, bottom-heavy IMF variations bring the mean FP coefficients into close agreement with observational constraints for both direct and orthogonal fits, while the simulated FP remains thinner than the observed relation. Our results suggest that a significant fraction of the long-standing FP tension arises from how galaxy observables are extracted and interpreted in simulations, although residual discrepancies may still reflect limitations in the underlying baryonic physics. These findings highlight the importance of observational realism and IMF variations for interpreting galaxy scaling relations and for improving the predictive power of hydrodynamical simulations of ETG formation.
SN - 0035-8711
SN - 1365-2966
ER -