Gas rotation and turbulence in the galaxy cluster Abell 2029

Abstract

We constrain the rotation and turbulent support of the intracluster medium (ICM) in Abell 2029 (A2029), using dynamical equilibrium models and a combination of state-of-the-art X-ray datasets. We reduce and conduct the spectral analysis of the XRISM/Resolve data. The rotating, turbulent ICM in the model has a composite polytropic distribution in equilibrium in a spherically-symmetric, cosmologically motivated dark halo. The profile of rotation velocity and the distribution of turbulent velocity dispersion are described with flexible functional forms, consistent with the properties of synthetic clusters formed in cosmological simulations. Adopting realistic profiles for the metallicity distribution of the ICM and for the point spread function of XRISM and XMM-Newton, we tune via a Markov chain Monte Carlo algorithm the observables of the intrinsic quantities of the plasma in our model to reproduce the radial profiles of the thermodynamic quantities as derived from the spectral analysis of the XMM-Newton and Planck maps and the measurements of the line-of-sight (LOS) non-thermal velocity dispersion and redshift (probing the LOS velocity) in the XRISM pointings. Our model accurately reproduces the measurements of redshift and LOS non-thermal velocity dispersion, as further demonstrated by simulating and analyzing synthetic counterparts of the XRISM spectra, in accordance with the posterior distribution of our model. We find turbulence-to-total pressure ratio $\approx$ 2% across the (0 - 650) kpc radial range, and a rotation-to-dispersion velocity ratio peaking at 0.15 between 200 - 600 kpc. The hydrostatic-to-total mass ratio is $\approx$ 0.97 at r2500, the radius enclosing an overdensity of 2500 times the average value.