Data and code associated with the Altamura et al. (2025) paper
Entropy plateaus can emerge from gas replacement at a characteristic halo mass in simulated groups and clusters of galaxies
Authors: Edoardo Altamura, Scott T. Kay, Joop Schaye, Ian G. McCarthy, Matthieu Schaller
Documentation: https://edoaltamura.github.io/entropy-core-evolution/
This repository contains the data and analysis scripts useful to reproduce the
results of Altamura et al. (2025, Paper II). Paper II investigates the emergence of entropy
plateaus in simulated galaxy groups and clusters using cosmological hydrodynamic
zoom-in simulations with the SWIFT-EAGLE model. It builds directly on the
Summary of main science (click to expand)
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Entropy plateaus emerge at characteristic halo-mass scales. Simulations of a galaxy group
$M_{500}\simeq8.8\times10^{12}$ $M_\odot$ ) and a cluster ($M_{500}\simeq2.9\times10^{14}$ $M_\odot$ ) show that once a halo reaches$M\sim10^{12}$ $M_\odot$ , its entropy profile flattens at the virial radius. As the halo grows to$\sim10^{13}$ $M_\odot$ , the plateau extends inward, and by$\sim10^{14}$ $M_\odot$ a fully isentropic core is established. -
AGN feedback is the principal mechanism. Lagrangian tracking of gas particles reveals that AGN outbursts expel low-entropy gas before it can accrete into the core, replacing it with higher-entropy material and erasing the central gradient needed for a cool core.
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Transition coincides with peak SMBH activity. The onset of the entropy plateau at
$M\sim10^{12}$ $M_\odot$ aligns with the maximum in the specific black-hole accretion rate, indicating a shift from supernova-dominated to AGN-dominated thermodynamic regulation. -
Numerical convergence. High-resolution runs (gas particle mass
$m_{\rm gas}\lesssim2.3\times10^5$ $M_\odot$ ) confirm that the entropy plateau persists even when subgrid physics is resolved on smaller scales. -
Comparison with observations. XMM–Newton studies of local groups report entropy excesses and flat cores consistent with the predicted plateaus, while many clusters still exhibit steep, cool-core power laws. Reproducing the observed diversity of entropy profiles remains a challenge.
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Implications for AGN subgrid modeling. The tendency to over-eject low-entropy gas suggests that current feedback prescriptions may be too aggressive at group scales. Adaptive efficiency schemes or hybrid thermal–kinetic models may be required to recover the full spectrum of entropy shapes without compromising other cluster properties.
- ArXiv:
https://arxiv.org/abs/2505.05675 - NASA ADS:
https://ui.adsabs.harvard.edu/abs/2025arXiv250505675A/abstract - Google Scholar
https://scholar.google.com/citations...isC
If you use this repository or its data in your work, please cite the relevant papers as
described in the CITATION.bib file with the bibtex handles.
Tip
You can generate bibtex handles or a text citation in your preferred style automatically
from NASA ADS's citation subpage (https://ui.adsabs.harvard.edu/abs/2025arXiv250505675A/exportcitation)
├── data/ # Simulation data products
├── analysis_scripts/ # Analysis scripts to generate the data products
├── figures_scripts/ # Scripts to generate the figures from data products
└── img/ # Figures from the paper (pdf) and other visualisations
- Clone this repository
git clone https://github.com/edoaltamura/entropy-core-evolution.git
cd entropy-core-evolution- Create and activate the environment
This project is licensed under the Apache License Version 2.0.
The authors thank Adrian Jenkins and Alastair Basden for high-performance computing support. This work used the DiRAC@Durham facility managed by the Institute for Computational Cosmology on behalf of the STFC DiRAC HPC Facility (https://dirac.ac.uk). The equipment was funded by BEIS capital funding via STFC capital grants ST/K00042X/1, ST/P002293/1, ST/R002371/1 and ST/S002502/1, Durham University, and STFC operations grant ST/R000832/1. DiRAC is part of the National e-Infrastructure. EA acknowledges the STFC studentship grant ST/T506291/1 and support from the Jodrell Bank Centre for Astrophysics at the University of Manchester.