We propose a model for the source of the X-ray background ( XRB ) in which low luminosity active nuclei ( L \sim 10 ^ { 43 } \hbox { $ { \thinspace erg } { \thinspace s } ^ { -1 } $ } ) are obscured ( N \sim 10 ^ { 23 } { cm } ^ { -2 } ) by nuclear starbursts within the inner \sim 100 pc .
The obscuring material covers most of the sky as seen from the central source , rather than being distributed in a toroidal structure , and hardens the averaged X-ray spectrum by photoelectric absorption .
The gas is turbulent with velocity dispersion \sim { few } \times 100 \hbox { $ { \thinspace km } { \thinspace s } ^ { -1 } $ } and cloud-cloud collisions lead to copious star formation .
Although supernovae tend to produce outflows , most of the gas is trapped in the gravity field of the starforming cluster itself and the central black hole .
A hot ( T \sim 10 ^ { 6 } -10 ^ { 7 } K ) virialised phase of this gas , comprising a few per cent of the total obscuring material , feeds the central engine of \sim 10 ^ { 7 } \hbox { $ \thinspace M _ { \odot } $ } through Bondi accretion , at a sub-Eddington rate appropriate for the luminosity of these objects .
If starburst-obscured objects give rise to the residual XRB , then only 10 per cent of the accretion in active galaxies occurs close to the Eddington limit in unabsorbed objects .