XRISM Reveals a Kinematically Coherent Core System of the Nearby Cool-Core Cluster Abell 2199

Abstract

We present the results of a deep 251 ks XRISM/Resolve observation of the cool core of the galaxy cluster Abell 2199. From the integrated spectrum of the central $3^{\prime }\times 3^{\prime }$ Resolve field of view ($104\times 104{\mathrm{kpc}}^2$), we find that the intracluster medium (ICM) redshift is consistent with that of the brightest cluster galaxy, within the optical-redshift uncertainty. This indicates that they form a kinematically coherent core system, which offset from the mean cluster redshift by $\sim 200\mathrm{km}{\mathrm{s}}^{-1}$. The observed velocity dispersion of $\sim 100\mathrm{km}{\mathrm{s}}^{-1}$ corresponds to a three-dimensional Mach number of $M_{3D}=0.16$ and a non-thermal pressure fraction of $P_{\mathrm{NT}}/P_{\mathrm{tot}}=1.4\pm 0.2$%. Abell 2199 is one of the most dynamically quiescent relaxed clusters observed with XRISM, despite the presence of radio jets and a plume-like structure possibly associated with sloshing motions. Order-of-magnitude estimates suggest that turbulent dissipation could offset a non-negligible fraction of the radiative cooling losses, with $Q_{\mathrm{turb}}/Q_{\mathrm{cool}}\approx 0.2$ for a large-scale driver such as sloshing and larger values for smaller AGN-feedback scales. Finally, we detect a localized enhancement of the Fe XXV He$\alpha$ $y$ line in the southeast region, which spatially coincides with a Chandra surface brightness discontinuity.

15 pages, 10 figures, 2 tables, Submitted to PASJ