Kavli Affiliate: Michael McDonald
| First 5 Authors: Tom Rose, Tom Rose, , ,
| 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
$10^61$ 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 $164pm10$ km/s. 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.
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