We present a Chandra observation of the only low redshift , z = 0.299 , galaxy cluster to contain a highly luminous radio-quiet quasar , H1821+643 .
By simulating the quasar PSF , we subtract the quasar contribution from the cluster core and determine the physical properties of the cluster gas down to 3 \arcsec ( 15 \thinspace kpc ) from the point source .
The temperature of the cluster gas decreases from 9.0 \pm 0.5 \thinspace keV down to 1.3 \pm 0.2 \thinspace keV in the centre , with a short central radiative cooling time of 1.0 \pm 0.1 \thinspace Gyr , typical of a strong cool-core cluster .
The X-ray morphology in the central 100 \thinspace kpc shows extended spurs of emission from the core , a small radio cavity and a weak shock or cold front forming a semi-circular edge at \sim 15 \arcsec radius .
The quasar bolometric luminosity was estimated to be \sim 2 \times 10 ^ { 47 } \hbox { $ \thinspace erg \thinspace s ^ { -1 } $ } , requiring a mass accretion rate of \sim 40 \hbox { $ \hbox { $ \thinspace M _ { \odot } $ } \thinspace yr ^ { -1 } $ } , which corresponds to half the Eddington accretion rate .
We explore possible accretion mechanisms for this object and determine that Bondi accretion , when boosted by Compton cooling of the accretion material , could provide a significant source of the fuel for this outburst .
We consider H1821+643 in the context of a unified AGN accretion model and , by comparing H1821+643 with a sample of galaxy clusters , we show that the quasar has not significantly affected the large-scale cluster gas properties .