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Peer-reviewedCC BY 4.0Astron.Astrophys.

Planck Constraints on Turbulence in the Coma Cluster

  • Baptiste Sigal
  • Etienne Pointecouteau
  • Nicolas Clerc
  • Simon Dupourqué
  • Alexeï Molin
  • François Mernier
  • Rémi Adam
  • Tanguy Dusserre
  • François Pajot
Open at sourcePDFDOICite

Abstract

Turbulence within the intracluster medium (ICM) influences galaxy cluster thermodynamics and virialisation, contributing to non-thermal pressure support and impacting hydrostatic mass estimates. Characterising this turbulence through thermodynamic fluctuations remains observationally challenging due to the non-linear relationships between observables such as density and pressure, and the underlying velocity field. This study aims to constrain the properties of ICM turbulence by performing a comprehensive reanalysis of the Sunyaev-Zel'dovich (SZ) surface brightness fluctuations based on Planck survey observations of the Coma cluster. We analyse the 2D power spectrum of SZ fluctuations, modelling the underlying 3D pressure fluctuation power spectrum assuming Kolmogorov-type turbulence. We infer key parameters from a simulation-based inference framework relying on normalizing flows to accurately recover posterior distributions. By constraining the pressure fluctuation power spectrum, we are able to infer the properties of turbulence in the Coma cluster, finding a large injection scale of linj = 540+450−200 kpc, a slope of α= 3.50−0.46+0.50 (under Gaussian prior), and a substantial 3D Mach number of ℳ3D = 0.60+0.13−0.09. These values correspond to turbulent velocities in the range σv, 3D = 357−1095 km/s and a non thermal pressure fraction of Pturb/Ptot = 0.17−0.04+0.06. Our results are consistent with recent direct velocity measurements from XRISM, supporting a scenario of significant turbulence in the Coma cluster and highlighting the complex interplay of dynamical processes within its ICM. Our simulation-based inference approach applied to SZ fluctuations paves the way for systematic multi-probe studies combining SZ and X-ray data, as well as direct and indirect observations.

Versions

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Cite

BibTeXRIS
BibTeX
@article{sigal2026planck,
  title = {{Planck Constraints on Turbulence in the Coma Cluster}},
  author = {Baptiste Sigal and Etienne Pointecouteau and Nicolas Clerc and Simon Dupourqué and Alexeï Molin and François Mernier and Rémi Adam and Tanguy Dusserre and François Pajot},
  journal = {Astron.Astrophys.},
  year = {2026},
  month = jul,
  doi = {10.1051/0004-6361/202661080},
  eprint = {2607.29414},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-05733697v1},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Planck Constraints on Turbulence in the Coma Cluster
AU  - Baptiste Sigal
AU  - Etienne Pointecouteau
AU  - Nicolas Clerc
AU  - Simon Dupourqué
AU  - Alexeï Molin
AU  - François Mernier
AU  - Rémi Adam
AU  - Tanguy Dusserre
AU  - François Pajot
PY  - 2026
DA  - 2026/07/31
JO  - Astron.Astrophys.
DO  - 10.1051/0004-6361/202661080
UR  - https://hal.science/hal-05733697v1
AB  - Turbulence within the intracluster medium (ICM) influences galaxy cluster thermodynamics and virialisation, contributing to non-thermal pressure support and impacting hydrostatic mass estimates. Characterising this turbulence through thermodynamic fluctuations remains observationally challenging due to the non-linear relationships between observables such as density and pressure, and the underlying velocity field. This study aims to constrain the properties of ICM turbulence by performing a comprehensive reanalysis of the Sunyaev-Zel'dovich (SZ) surface brightness fluctuations based on Planck survey observations of the Coma cluster. We analyse the 2D power spectrum of SZ fluctuations, modelling the underlying 3D pressure fluctuation power spectrum assuming Kolmogorov-type turbulence. We infer key parameters from a simulation-based inference framework relying on normalizing flows to accurately recover posterior distributions. By constraining the pressure fluctuation power spectrum, we are able to infer the properties of turbulence in the Coma cluster, finding a large injection scale of l_inj = 540^+450_−200 kpc, a slope of α= 3.50_−0.46^+0.50 (under Gaussian prior), and a substantial 3D Mach number of ℳ_3D = 0.60^+0.13_−0.09. These values correspond to turbulent velocities in the range σ_v, 3D = 357−1095 km/s and a non thermal pressure fraction of P_turb/P_tot = 0.17_−0.04^+0.06. Our results are consistent with recent direct velocity measurements from XRISM, supporting a scenario of significant turbulence in the Coma cluster and highlighting the complex interplay of dynamical processes within its ICM. Our simulation-based inference approach applied to SZ fluctuations paves the way for systematic multi-probe studies combining SZ and X-ray data, as well as direct and indirect observations.
ER  -