Kavli Affiliate: Michael McDonald
| First 5 Authors: Tom Rose, B. R. McNamara, Julian Meunier, A. C. Fabian, Helen Russell
| Summary:
We present XRISM Resolve observations centered on Hydra-A, a redshift z =
0.054 brightest cluster galaxy which hosts one of the largest and most powerful
FR-I radio sources in the nearby Universe. We examine the effects of its high
jet power on the velocity structure of the cluster’s hot atmosphere. Hydra-A’s
central radio jets have inflated X-ray cavities with energies upward of
$10^{61}~rm erg$. They reach altitudes of 225 kpc from the cluster center,
well beyond the atmosphere’s central cooling region. Resolve’s $3times3$
arcmin field-of-view covers $190times190$ kpc, which encompasses most of the
cooling volume. We find a one dimensional atmospheric velocity dispersion
across the volume of $164pm10,rm{km,s}^{-1}$. The fraction in isotropic
turbulence or unresolved bulk velocity is unknown. Assuming pure isotropic
turbulence, the turbulent kinetic energy is $2.5,%$ of the thermal energy
radiated away over the cooling timescale, implying that kinetic energy must be
supplied continually to offset cooling. While Hydra-A’s radio jets are powerful
enough to supply kinetic energy to the atmosphere at the observed level,
turbulent dissipation alone would struggle to offset cooling throughout the
cooling volume. The central galaxy’s radial velocity is similar to the
atmospheric velocity, with an offset of $-37 pm 23,$ km s$^{-1}$.
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