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XRISM constraints on the velocity power spectrum in the Coma cluster

D Eckert, M Markevitch, JA ZuHone… - arXiv preprint arXiv …, 2025 - arxiv.org
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… Here we propose a simulation-based inference technique to retrieve the properties of the velocity power spectrum from X-ray micro-calorimeter data by generating …

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@article{2510.21918v1,
Author        = {D. Eckert and M. Markevitch and J. A. ZuHone and M. Regamey and I. Zhuravleva and Y. Ichinohe and N. Truong and N. Okabe and D. R. Wik},
Title         = {XRISM constraints on the velocity power spectrum in the Coma cluster},
Eprint        = {2510.21918v1},
ArchivePrefix = {arXiv},
PrimaryClass  = {astro-ph.CO},
Abstract      = {The velocity field of intracluster gas in galaxy clusters contains key
information on the virialization of infalling material, the dissipation of AGN
energy into the surrounding medium, and the validity of the hydrostatic
hypothesis. The statistical properties of the velocity field are characterized
by its fluctuation power spectrum, which is usually expected to be well
described by an injection scale and a turbulent cascade. Here we propose a
simulation-based inference technique to retrieve the properties of the velocity
power spectrum from X-ray micro-calorimeter data by generating simulations of
Gaussian random fields from a parametric power spectrum model. We forward model
the measured bulk velocities and velocity dispersions by including the most
relevant observational effects (projection, emissivity weighting, PSF
smearing). We then train a neural network to learn the mapping between the
power spectrum parameters and the generated data vectors. Considering a
three-parameter model describing turbulent energy injection on large scales and
a power-law cascade, we found that two XRISM/Resolve pointings are sufficient
to accurately determine the turbulent Mach number and set interesting
constraints on the injection scale. Applying our method to the Coma cluster
data, we obtain a model that is characterized by a large injection scale that
rivals the size of the cluster ($\ell_{inj}=2.2_{-1.0}^{+2.0}$ Mpc). When this
power spectrum model is integrated over the cluster scales ($0<\ell<R_{500}=1.4
$Mpc), the Mach number of the gas motions is
$\mathcal{M}_{3D,500}=0.45_{-0.13}^{+0.18}$, which exceeds the value derived
from the velocity dispersions only. Further observations covering a wider area
are required to decrease the cosmic variance and constrain the slope of the
turbulent cascade.},
Year          = {2025},
Month         = {Oct},
Url           = {http://arxiv.org/abs/2510.21918v1},
File          = {2510.21918v1.pdf}
}

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