Kavli Affiliate: Eric D. Miller
| First 5 Authors: Congyao Zhang, Congyao Zhang, , ,
| Summary:
In this paper, we present extended gas kinematic maps of the Perseus cluster
by combining five new XRISM/Resolve pointings observed in 2025 with four
Performance Verification datasets from 2024, totaling 745 ks net exposure. To
date, Perseus remains the only cluster that has been extensively mapped out to
~0.7$r_2500$ by XRISM/Resolve, while simultaneously offering sufficient
spatial resolution to resolve gaseous substructures driven by mergers and AGN
feedback. Our observations cover multiple radial directions and a broad
dynamical range, enabling us to characterize the intracluster medium kinematics
up to the scale of ~500 kpc. In the measurements, we detect high velocity
dispersions ($simeq$300 km/s) in the eastern region of the cluster,
corresponding to a nonthermal pressure fraction of $simeq$7-13%. The velocity
field outside the AGN-dominant region can be effectively described by a single,
large-scale kinematic driver based on the velocity structure function, which
statistically favors an energy injection scale of at least a few hundred kpc.
The estimated turbulent dissipation energy is comparable to the gravitational
potential energy released by a recent merger, implying a significant role of
turbulent cascade in the merger energy conversion. In the bulk velocity field,
we observe a dipole-like pattern along the east-west direction with an
amplitude of $simeqpm$200-300 km/s, indicating rotational motions induced by
the recent merger event. This feature constrains the viewing direction to
~30$^circ$-50$^circ$ relative to the normal of the merger plane. Our
hydrodynamic simulations suggest that Perseus has experienced at least two
energetic mergers since redshift z~1, the latest associated with the radio
galaxy IC310. This study showcases exciting scientific opportunities for future
missions with high-resolution spectroscopic capabilities (e.g., HUBS, LEM, and
NewAthena).
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