Baryonification IV: Constraining baryonic feedback with X-ray gas fractions
Abstract
Baryonic feedback redistributes gas around dark matter halos, suppressing the matter power spectrum at scales now probed by weak lensing surveys. X-ray observations directly trace this hot gas, and are one of the main probes of its distribution and properties. We present a forward-modelling framework, built on the baryonification model, linking the three-dimensional gas density and temperature profiles of groups and clusters to observed X-ray surface brightness and luminosity profiles on one side, and to matter power spectrum suppression on the other. We validate the model against independent three-dimensional density reconstructions from the literature, and examine our temperature and metallicity treatment in the group-scale regime. Applying this framework to the SZ-selected CHEX-MATE and X-ray-selected eFEDs samples, we measure gas fractions across the group-to-cluster mass range while accounting for X-ray selection effects, with the first published gas fractions based on CHEX-MATE data. Combining both samples, we derive a joint constraint on the hot gas fraction retained by groups and clusters as a function of mass and on the baryonic suppression of the matter power spectrum. We find fgas = 0.029 ± 0.006 at M500c = 3× 1013M⊙, fgas = 0.078 ± 0.004 at M500c = 3× 1014M⊙, and suppression of 6% at k=1 h/Mpc and 23% at k=5 h/Mpc. Our findings are consistent with recent kinematic Sunyaev-Zel'dovich results, hinting at strong feedback. We also show that the LX-M relation is degenerate with feedback strength, and that different feedback scenarios produce distinct X-ray profile shapes that map onto the same LX-M point. This work is a first step toward extending the framework to forward-model diffuse X-ray emission at the map level for simulation-based inference in upcoming wide-area X-ray surveys such as eROSITA.
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BibTeX
@misc{bucko2026baryonification,
title = {{Baryonification IV: Constraining baryonic feedback with X-ray gas fractions}},
author = {Jozef Bucko and Andrina Nicola and Aurel Schneider and Michael Kovač and Sambit K Giri and Robert Reischke and Esra Bulbul and Nicolas Clerc and Ang Liu and Iacopo Bartalucci and Alexandre Refregier},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.09144},
eprint = {2609.09144},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05770568v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Baryonification IV: Constraining baryonic feedback with X-ray gas fractions
AU - Jozef Bucko
AU - Andrina Nicola
AU - Aurel Schneider
AU - Michael Kovač
AU - Sambit K Giri
AU - Robert Reischke
AU - Esra Bulbul
AU - Nicolas Clerc
AU - Ang Liu
AU - Iacopo Bartalucci
AU - Alexandre Refregier
PY - 2026
DA - 2026/09/08
PB - HAL
DO - 10.48550/arxiv.2609.09144
UR - https://hal.science/hal-05770568v1
AB - Baryonic feedback redistributes gas around dark matter halos, suppressing the matter power spectrum at scales now probed by weak lensing surveys. X-ray observations directly trace this hot gas, and are one of the main probes of its distribution and properties. We present a forward-modelling framework, built on the baryonification model, linking the three-dimensional gas density and temperature profiles of groups and clusters to observed X-ray surface brightness and luminosity profiles on one side, and to matter power spectrum suppression on the other. We validate the model against independent three-dimensional density reconstructions from the literature, and examine our temperature and metallicity treatment in the group-scale regime. Applying this framework to the SZ-selected CHEX-MATE and X-ray-selected eFEDs samples, we measure gas fractions across the group-to-cluster mass range while accounting for X-ray selection effects, with the first published gas fractions based on CHEX-MATE data. Combining both samples, we derive a joint constraint on the hot gas fraction retained by groups and clusters as a function of mass and on the baryonic suppression of the matter power spectrum. We find f_gas = 0.029 ± 0.006 at M_500c = 3× 10^13M_⊙, f_gas = 0.078 ± 0.004 at M_500c = 3× 10^14M_⊙, and suppression of 6% at k=1 h/Mpc and 23% at k=5 h/Mpc. Our findings are consistent with recent kinematic Sunyaev-Zel'dovich results, hinting at strong feedback. We also show that the L_X-M relation is degenerate with feedback strength, and that different feedback scenarios produce distinct X-ray profile shapes that map onto the same L_X-M point. This work is a first step toward extending the framework to forward-model diffuse X-ray emission at the map level for simulation-based inference in upcoming wide-area X-ray surveys such as eROSITA.
ER -