X-ray observations of the core of the Perseus cluster reveal a remarkably quiescent atmosphere in which the gas has a line-of-sight velocity dispersion of about 164 kilometres per second in the region 30–60 kiloparsecs from the central nucleus; turbulent pressure support in the gas is four per cent of the thermodynamic pressure, necessitating only a small correction to the total cluster mass determined from hydrostatic equilibrium.
- Felix Aharonian
- Hiroki Akamatsu
- Abderahmen Zoghbi
