How do black hole jets keep cluster cores from cooling? · revision history
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- Title
- How do black hole jets keep cluster cores from cooling?
- Plain
- Gas at the centers of galaxy clusters radiates away its heat in less than a billion years, yet it forms stars at only a few percent of the expected rate. Jets from the central black hole carry enough energy, but how that energy spreads evenly through the gas is not known.
- Precise
- In cool-core clusters the central gas has cooling time $t_{\mathrm{cool}}<1\ \mathrm{Gyr}$ within $\sim 100\ \mathrm{kpc}$, while star formation rates are $\sim 1\text{-}10\ \mathrm{percent}$ of classical cooling-flow rates of $10^2\text{-}10^3\ M_{\mathrm{sun}}/\mathrm{yr}$. Determine how jet mechanical power $P_{\mathrm{jet}}\sim 10^{44}\text{-}10^{46}\ \mathrm{erg/s}$ is converted to heat nearly isotropically: weak shocks, sound waves, turbulent dissipation, cosmic-ray heating, or turbulent mixing. The answer is the heating rate per channel versus radius matched to the cooling rate.
- Settled by
- High-resolution X-ray spectroscopy of gas velocities and temperatures in cluster cores (XRISM and successors) combined with simulations reproducing the measured velocity structure and the heating balance.
- Kind
- phenomenon
- Answer type
- mechanism
- References
- (empty)
- Literature status
- partially-resolved
- Status note
- Jet cavity energetics match the cooling luminosity; Hitomi in 2016 measured a line-of-sight velocity dispersion of about $1.6x10^{7}\,\mathrm{cm}/\mathrm{s}$ in the Perseus core, and XRISM has been measuring cluster core velocities since 2024.
- Posed since
- (empty)