Gas Motions in Hydra-A: XRISM Constraints on ICM Kinematics Across Jet-Inflated Cavities

We report on two deep XRISM observations of the central and northern regions of Hydra-A's X-ray atmosphere covering the bubbles inflated by jets from the central galaxy's active galactic nucleus (AGN). We use spatial-spectral mixing that combines Chandra's high spatial resolution with XRISM's high spectral resolution to investigate atmospheric kinematics. The atmospheric velocity dispersion in the northern region, sigma v = 140+30-20 km s-1, is comparable to that in the central region (sigma v = 162 plus or minus 10 km s-1). We show that the motion of the large-scale cocoon shock front could be responsible for the large dispersion toward the north. The velocity dispersion in the northeast quarter of the central pointing, sigma v = 260 plus or minus 50 km s-1, is among the highest dispersions measured. This region contains an X-ray-bright feature previously identified as metal-rich, possibly consisting of gas uplifted in the wake of previous-generation cavities. The dispersions in all other quarter regions are low (sigma v at most 120 km s-1) and consistent with previous XRISM results from other objects. The kinetic energy at the center is comparable to the enthalpies of the cavities, while in the north, it is roughly an order of magnitude smaller. The jet thus drives gas motion efficiently at smaller scales (r < 95 kpc) and inefficiently at larger scales (95-317 kpc toward the north along the jet). A bulk flow toward our line of sight of-100 plus or minus 30 km s-1 in the southwest quarter of the central pointing is also observed, possibly due to sloshing.