Using Chandra X-ray observations of nine nearby , X-ray luminous elliptical galaxies with good optical velocity dispersion measurements , we show that a tight correlation exists between the Bondi accretion rates calculated from the observed gas temperature and density profiles and estimated black hole masses , and the power emerging from these systems in relativistic jets .
The jet powers , which are inferred from the energies and timescales required to inflate cavities observed in the surrounding X-ray emitting gas , can be related to the accretion rates using a power law model of the form log ( P _ { Bondi } / 10 ^ { 43 } \hbox { $ { \thinspace erg } { \thinspace s } ^ { -1 } $ } ) = A + B log ( P _ { jet } / 10 ^ { 43 } \hbox { $ { \thinspace erg } { \thinspace s } ^ { -1 } $ } ) , with A = 0.65 \pm 0.16 and B = 0.77 \pm 0.20 .
Our results show that a significant fraction of the energy associated with the rest mass of material entering the Bondi accretion radius ( 2.2 ^ { +1.0 } _ { -0.7 } per cent , for P _ { jet } = 10 ^ { 43 } { \thinspace erg } { \thinspace s } ^ { -1 } ) eventually emerges in the relativistic jets .
The data also hint that this fraction may rise slightly with increasing jet power .
Our results have significant implications for studies of accretion , jet formation and galaxy formation .
The observed tight correlation suggests that the Bondi formulae provide a reasonable description of the accretion process in these systems , despite the likely presence of magnetic pressure and angular momentum in the accreting gas .
The similarity of the P _ { Bondi } and P _ { jet } values argues that a significant fraction of the matter entering the accretion radius flows down to regions close to the black holes , where the jets are presumably formed .
The tight correlation between P _ { Bondi } and P _ { jet } also suggests that the accretion flows are approximately stable over timescales of a few million years .
Our results show that the black hole ‘ engines ’ at the hearts of large elliptical galaxies and groups can feed back sufficient energy to stem cooling and star formation , leading naturally to the observed exponential cut off at the bright end of the galaxy luminosity function .